Stamen-carpel Homologies

Flora, Bd. 161, S. 184-208 (1972) Laboratoire de Phytomorphologie, Ecole des Hautes Etudes, Museum d'Histoire naturelle, Paris

Stamen-carpel Homologies By

MICHEL

GUEDES

With 90 figures (Received June 21, 1971)

Summary The study of intermediate phyllomes (stamen-carpels) in Salix as well as the reassessment of previous observations lead the author to put forward a general interpretation of homologies between stamen and carpel. The stamen is considered diplophyllous, i.e. with two tangential blades topping an unifacial filament. The four margins of these blades form the four pollen sacs. If the filament were hollow instead of solid, there would arise a congenitally closed cavity as in a peltate carpel. Its back part would bear the posterior blade of the diplophyllous anther, its front portion the anterior blade. The latter is made up of two congenitally fused anterior lobes, one on each side of the fusion line, prolonging the corresponding line of the filament. When the upper parts of the margins are no longer fused along this line in a peltate carpel the ventral split arises and in a diplophyllous stamen the two ventral lobes are freed, as seen in stamen-carpels of Tulipa. When such a process occurs together with disappearance of pollen sacs, ovule formation on the ventral split and merging of the ventral lobes in the posterior (main) blade, a carpel arises whose blade incorporates both posterior and anterior blades of the corresponding stamen (Tofieldia type, GUEDES 1965 a). When the anterior blade disappears, the posterior blade alone gives birth to the carpellary blade (Sernperviurn type, also found in Tulipa). In Veronica, Papaver and Salix, the anterior blade proper fades out too, but intermediate appendages arise between its constituting anterior lobes and the posterior blade. The placental appendages fuse with the posterior blade and develop the ovules. Since when the posterior blade of Sernpervivurn or Tulipa forms such ovules, narrow strips are also added to it distally, the first-mentioned genera must be referred to the Sernpervivurn type as well. In all these instances, anther and filament mayor may not take part in the formation of the fertile carpel portion. The issuing carpel is peltate or depending on to whether or not its blade margins are fused congenitally in their lower part. In teratohgically isolated carpels of Salix replacing stamens, the margins are congenitally fused up to the apex with some ovules being borne only basally, and this affords a clue to the interpretation of normal carpels in Typha, the Potamogetonaceae, the Bignoniaceae and the Caryophyllaceae. As far as possible, an ontogenetical interpretation of these phenomena is set forth, taking account of modern views (DULIEU, GUEDES) on foliage leaf ontogeny.

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Introduction

Although the classical interpretation of all Phanerogamous sterile and fertile appendages from cotyledons to carpels as homologous ph y II 0 m e s is by far the most widespread and the only correct one in my opinion (GUEDES 1966a; GUEDES and Dupuy 1970), many points must still be worked out with respect to detailed homologies between the various kinds of phyllomes. The homology between a stamen and a carpel is by no means self-evident. At first sight both have little more in common than their being dorsiventral and borne laterally on the floral axis (with notable exceptions in both respects). The concept of their homology dates back to LINNAEUS, WOLF and GOETHE (GUEDES 1969a), and all these authors drew this daring conclusion in part at least from teratological observations. These phyllomes may indeed be transformed into leaves, i.e. may be replaced by true ones or, most important, by appendages intermediate between leaves and themselves. They may also turn into each other. I tried to explain elsewhere how such well-defined stIUctures afford a factual support for the homology concept and enable one to determine the detailed homologies between two phyllomes (GUEDES 1970a; GUEDES and Dupuy 1970). The homology between the stamen and the petal or the vegetative leaf was keenly studied by BAUM, LEINFELLNER, Dupuy, ROHWEDER and others (main references in Dupuy 1963; GUEDES 1966a, 1971) on the basis of ontogenetical and teratological observations. The whole of these observations points to the diplophyllous interpretation of the stamen. If this has four pollen sacs borne by four margins and may teratologic ally proliferate into four-winged petals or leaves, it is because its filament is an unifacial solid structure in the same way as the unifacial solid petiole of a peltate carpel (GUEDES 1971), so bounded all round by the morphologically lower (dorsal) surface, and is prolonged at the anther level by two appressed blades. The back blade comprises the (dorso-) median bundle and the front one, though generally devoid of any bundle, may also show one or more inverted strands comparable with the ventral strands of a carpel (LEINFELLNER 1956; fig. 55). The medio-ventral longitudinal line of the filament is that of congenital fusion of margins, leading to unifaciality (dotted line on fig. 55), and it continues into the ventral or anterior blade of the anther. This arises therefore out of the fusion of two ventral or anterior lobes (one of which half -free in fig. 63). These fusion lines are not merely theoretical; they are evidenced when no fusion occurs in teratological instances. If, for example, the two anterior lobes remain free of each other, the anther will have two margin segments on its posterior blade, plus four others on its two anterior lobes. Six pollen sacs may be expected and are

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indeed found teratologically in Tulipa, although never all six at one time (GUEDES 1966b). Both anterior lobes are of course nothing but lateral lobes ("leaflets") of the posterior blade (fig. 68) severed from it by deep notches, turned forward, and merged along their former distal margin. The diplophyllous structure is often obscured in the adult state, but frequently is obvious during ontogeny (BAUM 1949) even when it is rapidly and deeply modified (BAUM and LEINFELLNER 1953). It may still be clear in the adult anther, especially from the basal continuity between both pollen sacs on each side and from the occurrence of two appressed sterile tips, one from each blade (BAUM 1953; LEINFELLNER 1957). Even when it does not appear during ontogeny or in adult morphology, teratology evidences the diplophyllous structure in showing two properly vascularized blades and an unifacial filament (BAUM 1952; JAEGER 1961; Dupuy 1963). It certainly cannot be argued that the four wings then appearing prove nothing more than the existence of four margins in the anther as maintained by TROLL and WEBER (1957), for as ROHWEDER (1959) observed: why would the anther have four margins instead of two if it were a normal phyllome? Diplophyllous vegetative leaves are sometimes found and are closely related to peltate and ascidiate ones, since their transition to the latter merely implies that their blades cease being tangentially appressed and fused and that two notches severing the anterior blade from the posterior one are "filled up". This may be seen is Bergenia (Dupuy 1963, with quotation of former literature). Now many carpels are precisely peltate (GUEDES 1971) and it appears that both sexual appendages in the flower are more closely related than might be expected. Carpel peltation is, howewer, generally imperfect in that carpel margins are congenitaly fused only basally, sometimes no higher than the top of the solid carpel petiole. For a stamen to be transformed into a carpel, peltate or ascidiate at least in part, the most direct way would be severance of the upper part of its ventral lobes from each other so as to render apparent the ventral split where ovules will appear. The inner surfaces of these lobes would also have to be freed from that of the posterior blade, and the two notches should disappear. A blade would then arise whose margins would be free and fertile above, this characterizing a peltate carpel (fig. 59). All this was indeed found in Tofieldia (LEINFELLNER 1962) and later served to define the Tofieldia type of stamen-carpel (GUEDES 1965a). In Sempervivum (GUEDES and Dupuy 1963) and Tulipa (GUEDES 1966b), howewer, the ventral lobes disappear, either while remaining tangentially fastened to the posterior blade (Sempervivum) or after having been freed from the latter and from each other (Tulipa, fig. 60). Only the posterior blade remains and gives rise to the whole carpel blade, without remnant of peltation in Sempervivum, but with a very short peltate zone in Tulipa, a point left untouched in my 1966b paper.

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Two further instances were studied including Veronica (GUEDES 1968) and Papaver (GUEDES 1969b). The anterior blade disappears in Papaver, but on each side of the posterior blade a strip of tissue is added upon which ovules develop. This case was referred to as a variant of the Tofieldia type, but erroneously, as discussed below. In Veronica, the anther loses its anterior blade, the posterior one becoming the style. The former filament becomes the ovary after hollowing and shortening. The placenta is borne at the cross-zone level (upper end of the fusion line of filament margins). Two free or fused strips may prolong the placental region (fig. 62a) and fuse with the posterior blade of the anther (fig. 62b). If each of them were separately merged in the corresponding margin of the posterior blade, the structure of the fertile region in Papaver would appear. Veronica too, was referred to the Tofieldia type, and this was erroneous as well, since the fusion line terminating in the cross-zone of the carpel is not that of the anterior lobes of the anther (see discussion). Both Veronica and Papaver will be shown to belong to the Sempervivurn type. Indeed, in the latter two thin placental strips are also added to the posterior blade margins, and the same can be said of Tulipa, but in none of these plants were they ever found free. A further case will now be studied, closely akin to Veronica and affording the opportunity for a general discussion of stamen-carpel homologies as also of some peculiar kinds of normal peltate carpels. Observations

Intersexual appendages are very common in Salix, especially among the hybrids widespread in this genus. An abundant material from various simple and complex hybrids was available to RAINIO (1927) by whom the pertinent older literature is cited. I have studied such stamen-carpels gathered from hybrid trees involving Salix babylonica L. and widely cultivated in Tours (France). No such hybrids were studied by RAINIO. My trees tally with the description of Salix X blanda ANDERSS. (S. sieboldii HORT., S. petzoldii HORT.) that is S. babylonica X S. fragilis L. Each tree as a whole is androgynous and in each wholly male or female catkins arc fairly scarce. Most catkins are also androgynous with a good proportion bearing androgynous phyllomes and not merely male and female zones. When only such zones are to be found on a catkin, they are sectorial or superposed, and their limits are generally abrupt. Normal male flowers These have two extrorse stamens located laterally with respect to the bract. The filaments are strongly hairy along a short stretch near their insertion. The anthers

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are four-locular without any indication of diplophylly (the two sacs on each side are discontinuous below, fig. 1). Two median nectaries are found on ad- and abaxial sides of the base of the pair of stamens. The more developed one is adaxial. Female flowers They comprise only one briefly stipitate ovary and one adaxial nectary scale; the whole is axillary to a bract. The ovary, glabrous on the exterior, is made up of two lateral carpels, the placentation is parietal, no peltate cavity may be found at the base of each carpel and the result is that even below there is only one ovary locule (fig. 48). Apart from the stalk, only the symplicate portion of the gynoecium is present (see GUEDES 1970b on the vertical zonation of syncarpous gynoecia). Each parietal placenta is much more developed basally and bears some ovules at this level. Higher up the placentae are sterile but still prominent and each is vascularized by a "synlateral" bundle, i.e. a bundle resulting from the fusion of two adjacent bundles from the two neighbouring carpellary margins of the two carpels. These bundles fade away in the apex below the stigmas, and only the median bundles of both carpels are still seen there. In keeping with the loculicidal dehiscence, the medians exhibit two phloem areas and a more or less homogeneous xylem in their lower region, but in the upper part of the gynoecium they become frankly divided into two small bundles between which the carpel will split (fig. 49). Something similar was found in Tulipa (GUEDES 1965 b). Each carpel has a bifid sessile stigma whose adaxial half is the smaller. Four stigmatic lobes, therefore, top the gynoecium. They cannot be deemed commissural or originating from placentae, but are rather the split products of two median stigmas and each receives half a median bundle. Stamen-carpels Stamens feminized to a minor degree exhibit a bifid stigma atop the otherwise nearly normal anther. The stigma appears superimposed to the male phyllome, as was the case in Sempervivum. The diplophyllous structure is still not visible in fairly common stamens such as that of fig. 12, for although both sacs on the left are confluent, the widened connective and filament shwo no hint of their unifaciality. In these case the filament is nearly normal in length, but in more modified phyllomes it is much more shortened and is thus drawn in full fig. 2-7. The orientation of feminized stamens tends to become gradually introrse. Many of the stamens mentioned below do not stand parallel with the plane containing the catkin axis and the main bract bundle. The turning about is generally completed when the carpel state is fully reached. This indicates that the extrorse state of the present stamen is not attained in the same way as that of many other extrorse ones (see below in discussion).

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Fig. 1-12. Salix X blanda. Fig. 1. Normal stamen, dorsal (outside) view. Fig. 2. Feminized stamen with a bifid stigma, only one anterior pollen sac continuous with the posterior one on the same side. Filament bifacial in its upper half. Compare fig. 64. Fig. 3. Same as fig. 2, but the anterior sac is severed from the corresponding posterior one. Fig. 4. Feminized stamen with stigma, still unifacial filament, and two reduced anterior sacs continuous with the posterior ones

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In fig. 4, the anterior pollen sacs are confluent with the posterior ones at their bases and reduced to their lower halves. Furthermore, while the filament is solid, a cross-zone (arrow) is visible above and continuous with the anterior pollen sacs. In fig. 3, this cross-zone is even more obvious because of its "dragging" at midconnective. The margins of the latter are therefore fused only in its lower half. The anterior sac is obvious though reduced on the right and lacking on the left. A stamen with two reduced anterior lobes and a mid-connective cross-zone is schematized on fig. 64. The disappearance of one anterior lobe leads to the structure of fig. 2. The stamen of fig. 3 would be analogous to the preceding one (with one reduced anterior lobe bearing a pollen sac on the left) were it not for the remnant of the anterior pollen sac on the right, which is not continuous with the free upper margin of the filament (arrow). In this instance an anterior lobe has been severed from the main blade margin, but has remained tangentially fused with this blade, as have the whole anterior blades in fig. 61, 62 and 66. Whe shall return to this point in the discussion. No intermediate stages leading to this result were found in Salix, but other diplophyllous phyllomes will be used for its interpretation. In fig. 51 only two posterior sacs are visible from the exterior, but a remnant of an anterior one appeared on cross-sections. The cross-zone is atop the filament; the latter is now inflated and hollow above. It may be guessed that as in Veronica this will be implied in forming the carpellary cavity. In the phyllomes of fig. 5-7, in addition to the posterior sacs, one (fig. 5-6) or two (fig. 7) remnants of the anterior sacs were seen on cross-sections. Each former cross-zone is here prolonged upwards by a solitary placental appendage, strictly median in fig. 7, somewhat lateral and free in fig. 5, lateral and fused with the posterior sac in fig. 6. These appendages terminate in small stigmas. Intermediates exist between wholly free and wholly fused ones.

on each side. Compare fig. 64. Cross-zone here atop the filament. Anterior blade divided into its two constituting anterior lobes. Fig. 5. Feminized stamen with free medio-ventral placental appendage. Fig. 6. Same with placental appendage fused on one side. Fig. 7. Same, with free lateral placental appendage, intermediate between fig. 5 and 6. Fig. 8. Very feminized stamen. Filament and anther turned into a peltate carpel with solid hairy unifacial stalk. Upper portion of a placental appendage still free. Small remnant of a posterior pollen sac. Compare fig. 18 to 19. Fig. 9. Same, without any remnant of pollen sac, nor placental appendage. In fig. 8 and 9, inner placental ridges visible through carpel wall. Fig. 10. Normal bicarpellary gynoecium, seen adaxially. Fig. 11. Feminized stamen with hollow filament and no anterior blade. Compare fig. 20-23. Fig. 12. Modified stamen with broadened upper filament and connective. Since these are still massive (anterior and posterior blades appressed) no indication of diplophylly is evident. As, anterior pollen sac; Pa, placental appendage; Ps posterior pollen sac; S, stigma; arrow, cross-zone.

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Reasons will be adduced for considering a medially-borne appendage to be dual in nature. Filaments are hollow above in these instances. In fig. 8, the carpel state is neared. At that time its rotation has about ended, and the deeply feminized stamen has become introrse. Lower down, at its hairy level, the phyllome is still solid; higher up it assumes the shape of a hollow cylinder. This is open above and the tip of the former placental appendage is still free ventrally. It would seem that this appendage, instead of being fastened to one fertile margin only as in fig. 6, is attached on both margins along most of its length. The posterior blade retains a remnant of pollen sac while the anterior blade is entirely missing. The lengthy cavity of this carpel is sterile, and the merged placental appendage shows up as an inside longitudinal outgrowth along most of the ventral suture. When the last pollen sac has disappeared and the solid petiole is shorter (fig. 9), there arises a peltate carpel without a free placental appendage, but with the corresponding inner placental ridge which now bears one to three ovules basally. In such a peltate carpel, the cross-zone is clearly just ·below the stigma, the whole cavity below it being congenitally closed, but the ovules are borne at the lower end of the line of congenital fusion (marked by a placental bundle) and not, as usual, at the cross-zone level. The fusion of two carpels will give rise to the dimerous gynoecium. The solid stalk loses its hairs, although a few may remain at the ovary base (fig. 10). Since the gynoecium is unilocular from base to top, the two normal carpels must be epeltate. No intermediate stages of their losing peltation were found, but some cases of fusion of two peltate carpels were observed, one of which not entirely turned about to an introrse location. The gynoecium was then bilocular with one of the median bundle not far from the placental ridge of the other carpel. Not infrequently pleiomerous unilocular gynoecia occur. One or both of their carpels have divided into two carpels, obvious from the occurrence of four stigmatic lobes atop each. Such variations are common in many other plants. While feminization is going on, the abaxial nectary scale gradually diminished in size and has disappeared when perfect isolated carpels or perfect gynoecia are obtained. Anatomical data from stamen-carpels In such stamens as those of fig. 2, 3, 4 and 12, no bundle is added to the single normal one; the collateral structure of the latter gives no indication of unifaciality of the filament. In this case external morphology is more informative than anatomy. In other appendages, interesting anatomical features are seen. In such a stamen as that of fig. 7, the one bundle in the filament base splits into three bundles the largest being the median one, corresponding to the only bundle of the normal stamen.

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Fig. 13-34. Salix X blanda. Fig. 13-17. Cross·sections through a stamen-carpel with a median placental appendage receiving two lateral bundles (fig. 16). Fig. 18-19. Cross-sections of phyllome of fig. 8. Fig. 20-23. Same of feminized stamen of fig. 11. There is no ventro-median, but one margin receives a lateral. Fig. 24-26. Stamen-carpel with a hollow filament provided with a ventro-median, perhaps proceeding to one of the margins of the posterior blade (see text). Fig. 27-28 and 29-31. Cross-sections of stamen-carpels with one anterior sac, and hollow filament provided with a ventro-median passing into a placental appendage fused below with the posterior blade. See text. Fig. 32-34. Cross-section of a stamen-carpel with a lateral bundle passing along one margin of the posterior blade. Same letters and L, L' lateral bundles; M, median bundle; Vm, ventro-median bundle (congenitally fused laterals).

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The other two are paired laterals (fig. 14). The filament is soon hollowed (fig. 14-15), with the pair of laterals opposite the median. On top of the filament the two laterals pass on into the free placental appendage (fig. 16), while the usual four pollen sacs appear, the anterior ones being the smaller. The latter are not very high, and the upper anther half has only the two posterior sacs (fig. 17) as in fig. 4. As stated above, anterior sacs no longer basally adjacent to the posterior sacs. The filament here appears as a peltate structure whose margins lie between the two laterals and are fused congenitally. The placental appendage is then made up of two marginal strips of the anther blade, each carrying a lateral bundle. Very often a placental appendage has only one bundle, and it may be difficult to decide whether this is the fusion product of the two laterals and therefore the ventro-median bundle (GUEDES 1971), or represents one of them only. In fig. 27-28 the anther retains only one anterior residual sac reaching down to the upper part of the peltate filament cavity (fig. 27). The solitary bundle Vm opposite the median already appears in this position in the solid filament base and although displaced laterally at the anther level, it must in my opinion be considered it ventro-median resulting from the fusion of the two laterals of the previous case. The placental appendage containing it is fused with the left posterior pollen sac (fig. 6). The same applies to the case shown in fig. 29-31 where the placental appendage is free above (fig. 31), unvascularized at this level and located as that of fig. 16. In the stamen-carpel of fig. 24-26, only one posterior sac remains, a ventromedian appears as usual in the solid filament base and runs along the ventral wall of the filament cavity (fig. 25), then passes on along the sterile thickened margin of the flat anther (fig. 26). At this level, we may have to deal with a bivalent placental appendage fused with the posterior blade, and the bundle may still be the dual ventro-median. But it might also be only half of it, i.e. the lateral corresponding to this margin. The second interpretation must probably be accepted for the whole bundle accompanying the median of the phyllome of fig. 20-23, in which the filament peltate cavity exhibits only its median at the base. An unquestionable lateral then branches off from it and reaches up to anther base, but disappears before the posterior pollen sac on its side is attained. In fig. 32-34, on the contrary, the lateral runs along the posterior sac, outstrips it, and proceeds to the sterile upper anther portion (fig. 34). In the case just-mentioned, a placental appendage topped by a small stigma is freed in the upper part of the anther. This appendage corresponds to only half of that of fig. 16 as it includes only one lateral (see also fig. 65 on the left). Fig. 11, on the other hand, represents the outward aspect of the stamen-carpel of fig. 20-23 and, understandably, no placental appendage can be seen free. 13

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Fig. 35-54a. Fig. 35-49. Salix X blanda. Fig. 35-39. Cross-sections of a stamen-carpel with a solid filament whose median sends forth a lateral (fig. 36). Anterior blade still present as one anterior lobe forming an anterior pollen sac (fig. 37). Median divided into two bundles at the base of the stigma (fig. 39). Fig. 40-45. Isolated carpel (compare fig. 9) with a basal ovule (fig. 42). Ventro-median continuing all along the placental ridge up to just below the stigma (fig. 45). Fig. 46. Fertile region of a comparable carpel, but with two ovules. Fig. 47-49. Crosssections of a normal gynoecium. No congenitally closed carpellary cavities. Lateral bundles of neighbouring margins fused into synlaterals, from which ovular bundles branch off. Fig. 50- 54 b. After R.uNIO, 1927. Stamen-carpels from various hybrid willows. Fig. 50. Two stamens have fused their inflated bifacial filaments into a carpellary locule. Fusion margins prolonged by dual placental appendages. Anthers still well recognizable, topped by long stigmas. Fig. 51. Same, but one placental appendage is on its way to fusing with the anther and style of one of the stamens. Fig.52. Same, fusion of the placental appendage on the Tight about ended, of that on the

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Moreover, a stamen with a still solid filament may also show a lateral (fig. 35-39, the phyllome was very similar in appearance to that of fig. 2). Here too the lateral is emitted at mid-connective and runs laterally along the base of a posterior sac (fig. 37), then disappears (fig. 38). In fig. 35-36 the filament is bifacial (compare fig. 2) and the lateral occupies one margin. There can be no question of its being dual and belonging to both margins. This, by comparison, lends support to my interpretation of the lateral in previous stamens with unifacial filaments. All these cases still assume a more or less clear male shape, but the median tends to become divided above into two little bundles, at least in its phloem, as in normal carpels (fig. 23, 26, 27). In fig. 18-19 two sections from the sterile carple of fig. 8 are shown. A ventromedian is present right from the solid base, it does not reach up to the upper portion of the phyllome (in which case it would, of course, pass up into the free placental appendage) but disappears below a remnant of posterior pollen sac (fig. 8, 19). In such carpels as that of fig. 9, no male tissue remains, a ventro-median moves off from the one bundle entering the solid carpel petiole and runs up to the cross-zone level where it fades out. Along its entire length, an inward ridge marks off the mostly sterile placental strip. Rather rarely this may be fertile, but only near the cavity base, and thus at exactly the same level as in the normal non-peltate carpel. Only one ovule may be borne on the medio-ventralline (fig. 42) or one ovule on each side (fig. 46) or three or four ovules may be situated in one of these ways. In any case the ventro-median continues above the upmost ovule into the long placental ridge. The ovules are thus not borne on the cross-zone, but on the fusion line of the margins of the peltate portion of the carpel or on each side of this line.

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* *reproduced in fig. 50-54. Here the staSome of RUC>!IOS (1927) drawings are mens began to fuse just after having turned to introrse positions. Styles and stigmas were added above anthers. Placental appendages were common (fig. 65-71) and corresponded to the fusion of two elementary appendages from the neighbouring margins of two different carpels (fig. 50-51). They were seen fusing with the anthers of one, then both, opposed feminized stamens (fig. 52). Cross-sections clearly showed

left limited to its uppermost part (postgenital fusion ?). Fig. 53. Cross-section of a couple of stamen-carpels the lower of which has still fourpollen sacs, the upper one has lost the posterior sacs. Placental appendages fused with both anthers at this level. Fig. 54. Cross-section of the lower anther zone in fig. 50. The anthers are still nearly perfect, with four sacs each. Fig. 54a. Isolated stamen-carpels, each with two placental appendages, fused along most of their lengths with the two corresponding posterior blade margins. See text and fig. 65. The phyllome on the left still had one pollen sac, that on the right had two. Same letters, and 0, ovule; 01' ovular bundles; Sl, syniateral bundles. 13*

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that these appendages were added laterally to the posteriDr blades of the stamens (fig. 53-54) with anterior pollen sacs located at first in carpellary cavity and fading away as feminization went on. This represents my interpret ation of RAINIOS observations whose own view of the question was quite different since he thought of the ovules as borne upon the medio-ventral line of the carpel and was hampere d in his conclusions by the general occurrence of carpels splitting during the process of masculinization, this leading to four carpels apparent ly corresponding to two stamens. Such meristic variations were also to be found in my material. Among such instances described by RAINIO, very interesting isolated carpels were found, however, with only their stalk unifacial, two placental appendages on their way to fusing with both edges of the main blades, and some remnants of anterior and posterior pollen sacs (fig. 54, 54a, 65). Discussi on

The extrors e stamen In the instances so far studied (BAUM and LEINFELLNER 1953) the extrorse stamen was simply one whose posterior blade was less developed than the anterior one. Since the latter was bent outwards, all sacs appeared on the outside of the flower (fig. 56). As might be expected, when a stamen turned into a petal the intermed iate phyllomes showed their posterior blades regaining their promine nt importance to give rise to the petal blade, with the anterior blade disappearing as is usual when a stamen turns into a normal (non-diplophyllous) petal (GUEDES 1965c in Escholtzia). In Salix, however, as also observed by Rainio (1927), the whole stamen is turned around, congenitally of course, since no rotation can be seen during ontogeny (AUBERT 1876) and since there is no anatomical indication of such (FISHER 1928). The blade facing to the inside of the flower is the posterior one and only after its rotation towards the outside can it be transformed into the normally situated carpellary blade. Speaking of congenital rotation of a phyllome means nothing more than that the latter is initiated inversely with respect to other phyllomes on the same plant. Subtle chemical changes related to factors determining stamen morphology probably lead to this inversion and they gradually return to normal when the conditions responsible for male morphology are replaced by others inducing carpel structure . These changes are quite reminiscent of the rotations and flattenings to be admitted for the components of the seed-scale complex of the Pinaceae, here on both palaeontological (FLORIN 1951) and teratological (GUEDES 1970a; GUEDES and Dupuy 1971) grounds. The inverse position of the stamen might perhaps be accounted for assuming that the male flower is a pseudant hium (HJELMQVIST 1948), but no cogent argument

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can be afforded for this view, and the female flower might then become very difficult to interpret (the fused carpels each of which corresponds to a stamen should be borne by two distinct axes). Diplophyllous structure. Severance of the anterior blade Little modified stamens provide us with facts in full accordance with the diplophyllous concept (fig. 4, 55) although the normal stamen has no external or anatomical structures suggesting it. However, the isolation of one or both anterior sacs on the ventral surface of an otherwise peltate phyllome (fig. 3, 27, 29, 65) moots a question which cannot be answered by data of the present study alone, but can be derived from previously studied teratological phenomena. In Narcissus the petaloid stamen was shown (GUEDES 1966c, with a reassessment of previous observations by CELAKOVSKY 1898) to sever its anterior blade through "pinching" at its base (fig. 57) so that the blade assumes a funnel shape with its margins continuing those of two lower pockets in the filaments (arrow on fig. 67). Such basal longitudinal pockets are seen also in stamen-carpels of Sempervivum (GUEDES and Dupuy 1963) and Veronica (GUEDES 1968). When the continuity from the anterior blade to the pockets is lost, the former may retain its funnel shape basally (fig. 58) or become flattened (fig. 61) and remain fastened to the posterior blade. The pockets become confluent through disappearance of the partition separating them which is nothing more than the appressed lower halves of the anterior blade (fig. 72). A free blade may then develop upwards from the free continuous margin and may wrap the remnant of the anterior blade (fig. 58,61). This free blade is made up of two lobes from the posterior one which are turned inside and fused along their margins. They are fundamentally located between the postl'rior blade and those of its lobes which give rise to the anterior blade and are hatched in fig. 69. They may fuse as the anterior blade has disappeared at the filament level where it was previously represented by the partition between the pockets (fig. 72). Since this blade is dual in nature, it is not surprising that it is medially notched on its upper edge in Narcissus and that it develops very often as two placental appendages in Veronica (fig. 62a, only the right appendage is drawn). If these two appendages are fused, the condition shown here for Salix (fig. 7 and 14-16) in which the anterior blade with its two pollen sacs is also severed and fused with the posterior blade results. Unfortunately, in that case no pinching of the anterior blade nor any pocket formation was noted. Yet it can be confidently hoped that they will be found in the future. As seen above, an appendage of simple nature is probably developed in some instances in Salix and fused with the neighbouring posterior blade margin. In Veronica I described instances of fusion of both placental appendages with each other and

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® Fig. 55-77. Interpretive schemes. Fig. 55. Diplophyllous stamen. Pollen sacs borne by posterior and anterior blades continuous on the right, not on the left. Ventral view. Fig. 55a. Cross-sections of a diplophyllous stamen supposed to have a ventro-median bundle; below, filament, above, anther. Fig. 56. Same of an extrorse stamen of e.g. Escholtzia, the posterior blade is less important than the anterior one. Fig. 57. Formation of two basal pockets and incipient isolation of the anterior blade by pinching (arrow) at its lower end (see text). Fig. 57a. Cross-sections of the preceding stamen, anterior wall of the basal pockets hatched. From below upwards, filament, basal pockets, funnel-shaped lower portion of the anterior blade fastened to the posterior one, upper normal diplophyllous region. The two arrows on the last but one scheme indicate the nearing of the basal pocket walls responsible for the formation of the funnel-shaped lower portion

Stamen-ca rpel Homologies

199

with posterior blade margins (fig. 62b), to create a cavity enclosing the anterior pollen sacs and whose wall still incorporated the posterior pollen sacs. Precisely the same structure is met with in Salix in fig. 27 and 29, but with only one remaining anterior sac (see also fig. 66-67).

Fig. 58. of the anterior blade, as seen just above, and the appearance of the partition (see fig. 72). growing now pockets, basal former the of wall the from blade anterior the of Below, severance ed. as a continuous blade (hatched). Above. Upper region, anterior blade no longer funnel-shap Tulipa. of Same 60. Fig. view. Ventral Tofieldia. of Compare fig. 61. Fig. 59. Stamen-ca rpel Compare Anterior blade now represented only by one of its two constitutin g anterior lobes. carried fig. 64. Fig. 61. Petaloid stamen of l\Tarcissus. Anterior blade reduced to an upper remnant pro-58) 57 fig. see (hatched, pockets basal the of wall upwards along the posterior blade. The its on Anther view. Ventral Veronica. of rpel Stamen-ca a. 62 Fig. blade. free a as ceeds upwards with blade Posterior above. way to becoming the style, still one remnant of anterior blade as as in one pollen sac only. Filament inflated into ovary. Superimpo sed tissue strips (hatched) left). the on occurs generally (another appendage placental a by prolonged 61 and 58 fig. 57, plaeental two with Veronica Fig. 62b. Cross-section at the anther level of a stamen-car pel of whose appendage s fused with each other and the posterior blade. Fig. 63. Diplophyllous stamen anterior two the Same, 64. Fig. view. Ventral lobes. anterior unequal two has anterior blade (arrow) lobes are much reduced in length and no longer fused with each other, so the cross-zone One 61-62. fig. Compare Salix. of carpel Stamen 65. Fig. has gone down along the filament. on Cross-secti 66. Fig. blade. posterior the with fused other the half-free, appendage placental 67. Fig. 16). fig. (compare of a stamen-car pel of Salix with a free dual placental appendage posterior Same, but the placental appendage has fused with one margin of the posterior blade, whose stamen ous Diplophyll 68. Fig. only. sac one with blade Anterior side. this on sacs reduced their along separated lobes anterior anterior blade has been severed from the posterior one, its to lead they (arrows) fused and forward turned If sides. ventral fusion line, and spread on both the between (hatched) lobes te intermedia two of nt Developme 69. Fig. 55. fig. of the structure (right) posterior blade and the anterior lobes. Fig. 70. One of the anterior lobes is turned forward . On appendage lateral free a as appears lobe te intermedia the giving rise to the normal anther, rest. the from separated deeply more lobe anterior but 69, fig. in as structure same the left, the on appendage The fig. Fig. 71. The two anterior lobes are as in the right half of the preceding a of filament ted two-pocke a of on Cross-secti 72. Fig. blade. left is fused with the posterior ventral the partition, the forms blade anterior The 57. fig. of that than modified more stamen s. wall is originated by superimpos ed tissue which may be prolonged by the placental appendage 57 fig. of those as stamens such of filaments of portion lower Fig. 73. Cross-section of the solid Superand 71. Anterior blade prolonged downwards by a strip of tissue with the ventro-med ian. imposed (hatched) tissue on both sides. Fig. 74-77. PeItate carpels. Fig. 74. Uniovulate carpel split along the ventral line of congenital from fusion. Fig. 75. When its blade is folded inwards (arrows on fig. 74) and its margins fused 74, fig. in as Same 76. Fig. below up to the ovular level, there arises the usual peltate carpel. the so 75, fig. in as is fusion the folding, inward After 77. Fig. but the ovule is borne near base. anterior ovule is basally located in the congenitall y closed cavity. See text. Same letters, and Ab, cross-zone; C. blade); anterior the blade; AI, anterior lobe (the fusion product of the two is Pa, Pa' placental appendage s on both sides.

200

M. GUiDES

In Veronica, however, this was purely teratological, as the normal style of every carpel was very narrow and retained only the median bundle. In Salix, on the other hand, the anther region becomes incorporated in the carpellary cavity and the placental appendages and their bundles are either teratologically in the same position as in teratological carpels of Veronica (fig. 8-9), or are separately fused with each free carpellary margin in the normal non-peltate carpel.

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Sempervivum and Tofieldia types of stamen-carpels

As remarked in the introduction, in the Sempervivum type only the posterior blade remains and originates the ovules. In Sempervivum these are borne below the pollen sacs. In Tulipa, however, which also belongs here, most ovules are on a level with the sacs (fig. 60). Compared with that of the stamen, the posterior blade forming the carpel is thus extended laterally to include two further longitudinal strips bearing the ovules. These strips were never seen free, but if they were so, they would correspond closely to the placental appendages of Veronica and Salix. Both of the last-named genera will therefore be considered to produce stamencarpels of the Sempervivum type, despite my former opinion about Veronica. I <11so erred in referring Papaver to the Tofieldia type (GUEDES 1969b). In Papaver as well, the placentae are indeed borne in part on a level with the posterior sacs without excluding them, and the anterior blade disappears in much the same way as in Salix. These stamen-carpels thus belong to the Sempervivum type. This type may also be termed intercalary, since the main (posterior) blade loses its former distal anterior lobes (fig. 68) after these have become the isolated upper portion of the anterior blade and the partition between the two pockets at the filament level (fig. 72). In addition, the main blade develops two in ter c al ary lobes between itself and the above-mentioned anterior lobes. These (hatched on fig. 61-62 a and 69-73 together with the tissue strips prolonging them into the regions where they are not free) give rise to the placental appendages destined to disappear (Veronica) or to fuse with the posterior blade (Sempervivum, Tulipa, Papaver, Salix). Regardless of their fate, in the closed part of the phyllome, if any, the intercalary strips of tissue which prolong them form the ventral wall of the hollow phyllome portion (fig. 57, 58, 61, 62a, 72) and in Veronica (fig. 62a) bear the ovules above. Judging from RAINIOS paper (1936-1937) Geranium also belongs to the Sempervivum type. Only Tofieldia remains in the Tofieldia type (fig. 59) with the former fusion margin of the original lateral lobes (fig. 68) being freed and ovuliferous. Work in progress, however, seems to indicate that Mahonia also belongs to this type (BARON, unpublished).

i, I

Stamen-carpel Homologies

201

"Vertical" homologies of stamen-carpels in Salix By comparison with the stamen, the present data show the stigma to be superimposed to the anther, as in all cases studied by me except for Veronica. In Hebe (HAMANN 1960), Sparganiurn and Typha (MULLER-DoBLIES 1970) no style or stigma is added above the anther level. As in Veronica, Papaver, Sernpervivurn and Tofieldia, the filament takes part in the formation of the carpellary wall at the level of the locule. FurthermOle, as in Papaver, Tulipa and Tofieldia, the posterior blade of the anther is also incorporated in it, and the whole blade originated by the hollow filament and the posterior anther blade (plus the placental appendages) is provided with two marginal placentas. These are fertile at their very bases only, that is, at about the level of the former filament base. Moreover, each such placenta is merged in its neighbour from the accompanying carpel in the normal gynoecium. The short solid gynoecium stalk appears to correspond to the fusion product of the two hairy lower filament segments of the stamens. Intersexual appendages loug retain their hairs at this level before eventually losing them on becoming wholly female (fig. 8, 9, 10, 11). Teratological and normal peltation Only teratologically is the Salix carpel peltate, but then very strongly so, with its margins fused up to just below the stigma (fig. 9) and resembling normal carpels of the Potamogetonaceae (EBER 1932). Moreover, even in a strongly peltate carpel a placental appendage may prolong the fusion line of the margins (fig. 8). Both dispositions have a direct bearing on still debated normal organizations. In Typha (MULLER-DoBLIES 1970) the carpel has margins fused congenitally along their whole length and its cross-zone is thus on top of the style, whilc the ovule is borne far below in the inflated carpellary locule (fig. 77). MULLER seeks to connect this to the usual type with ovules on the cross-zone (fig. 75) by pointing out that at the time of its initiation the ovule is not far from the cross-zone. However, he does not mention the possibility that this ovule is borne by the congenitally fused longitudinal margin upon which it is precisely located. Starting indeed from a non-peltate (epeltate) carpel bearing an ovule on one of its margins (fig. 74), I have shown that as a rule the peltate state arises when the margins located below ovule insertion are cOtlgenitally fused (fig. 75) with the ovule seated on what is now termed the cross-zone as a result (GUEDES 1971). But if congenital fusion reaches up to the same level as above and if the ovule turned into the inside of the carpel is borne near carpel base (fig. 76), it will be located well below the issuing cross-zone (fig. 77). That MULLER (1970) does not even contemplate this interpretation with respect to Typha is the more surprising as he

202

M.GUEDES

describes the teratological opening of the peltate carpel with one or two ovules appearing at mid-height on the then free longitudinal carpel margins (fig. 76). That fused margins may bear turned in ovules or placentae was put forward several years ago (GUEDES 1966c). It applies to "laminal placentation" in the peltate Potamogeltonaceous carpels (EBER 1932) and is borne out by investigations of the Bignoniaceous gynoecium (GUEDES 1970b). In the Caryophyllaceae (ROHWEDER 1967, 1970) most of the ovules are borne along double longitudinal lines in the congenitally fused peltate portions of the carpels, and the same interpretation holds true: each row of ovules is a product of the congenitally fused carpellary margins (better, a continuation of them, since ovules are simply carpel leaflets; see GUEDES and Dupuy 1970). In Cerastium and Moenchia, moreover, above the peltate portion of each carpel and between the free margins of the ventral split the placenta extends somewhat farther up. Since all five placentae from the five carpels are fused, there arises a central placental column between the five centrally free carpellary margins as described by PAYER (1857), ROTH (1963) and ROHWEDER (1970). This is closely reminiscent of fig. 8 from Salix where a placental appendage tops the placenta of the peltate carpel. It is common knowledge that many terata are "phenocopies" from dispositions normal elsewhere (WORSDELL 1915-1916; Dupuy 1963; GUEDES 1966a). An attempt at an ontogenetical interpretation The formations of lateral lobes, their turnings or the severances of anterior blades as postulated above may seem far-fetched and can, of course, only be inferred from examinations of intermediate adult states. Therefore, at least an attempt must be made to hypothesize about what really happens during the ontogenies of these various phyllomes. A good deal will still remain theoretical, but hopefully clues which may aid in choosing research material and interpreting it more correctly than has often been done may be provided. In morphology, as elsewhere, great attention must be paid to indirect data, particularly since it has been hitherto practically impossible to follow the development of a stem cell by cell (see, however, BARTELS 1960). Only indirect proofs from mericlinous chimaeras led to the important conclusion that only a few (one to three) initials in each layer may be involved in producing the shoot (STEWART and DERMEN 1970), for instance. In the same way these chimaeras show that the leaf arises from more than one initial and enable us to compare the basic architecture of various kinds of leaves (DULIEU 1967-1968) in full accordance with anatomical data (GUEDES 1969c-d). Other mutations show that a lateral shoot may arise from only one cell (BEARD 1970), a view confirmed histologically in the case of adventitious shoots in the flax stem (CROOKS 1936).

Stamen-carpel Homologies

203

Most of these results could not have been attained through direct histological observations, which, taken too literally, has led many authors to erroneous interpretations of leaf ontogeny (see DULIEU 1967-1968). Onto genetical observations are often no easier to interpret than those gained from gross morphology and anatomy. Actually, the latter and the information provided by teratology must often be used to interpret the former. Flower phyllomes exhibit a palmate venation even though foliage leaves are pinnately veined in the plants bearing them (EAMES 1931), but this is no surprise in view of the new interpretation of the leaves (DULIEU 1967-1968; GUEDES 1969c-d). A parallel-veined leaf is made up of parallel rows of cells; in the oat leaf these arise from three to five initials according to ICHIKAWA and IKUSHIMA'S data on chimaeras (1967). The rows develop mostly longitudinally and remain parallel as do the main leaf bundles (fig. 78). If the rows undergo several longitudinal divisions at definite times, they will broaden into fan-shaped leaf-sectors and the venation will become palmate (fig. 79). The main bundles will still follow the orientation of the cell rows to be admitted from the chimaeras. It may also happen that the cell rows broaden through such divisions only in their middle portion and the main bundles radiate from a petiole (in which they grow in parallel fashion and retain the same breadth) only to converge towards the apex (fig. 80 on the left). As regards the pinnately-veined leaf, both chimaeras and anatomy show the organization to be largely the same, but the cellular rows, having grown parallely while remaining narrow in the petiole and median nerve, cease doing so, bend outwards and broaden successively: the more lateral their position the earlier this occurs (fig. 80 on the right). There is thus no essential difference between parallel-, palmately-, and pinnately-veined leaves, and it is understandable that in the same plant relatively slight growth differences lead to the palmately- or parallel-veined floral phyllomes after a phase of production of pinnately-veined vegetative leaves. During incipient development, a leaf primordium will stretch laterally and, to a lesser extent, grow in thickness (fig. 81). The lateral stretching is very marked when Graminaceous, Liliaceous or Cyperaceous leaves extend round the apex. More and more cells, groups of which probably arise from divisions of single initials in the stem, become involved in contributing the leaf. If instead of fusing on the apex side opposite that of the median bundle, both leaf margins do so on the side of the latter, a peltate leaf will appear (fig. 82), growing as a tore after the meeting of the margins. Not rarely, it would appear that this phenomenon occurs only on a rounded sole representing the solid unifacial stalk has developed on the apex (TROLL and MEYER 1955), and the same may be said of a peltate carpel (see TUCKER and GIFFORD 1966; GUEDES 1971). Furthermore, it may happen that two opposite growth centres

204

M. GUEDES

exist, of which the first will contribute the main carpellary blade, starting with the region of the (dorso-) median bundle, and the second will originate the crosszone region. Both blades rapidly extend in opposite directions, and after they have

Fig. 78-90. Interpretive schemes. Fig. 78-80. Leaf architecture. Fig. 78. Parallel-veined leaf, cell rows and main bundles run parallely. Fig. 79. Palmately-veined leaf. Radiation of cell rows and main bundles at the petiole top. Fig. 80. Cell rows and main bundles diverge laterally at the petiole top but converge again towards the leaf tip (e.g., H osla). Right. Pinnately-veined leaf. See text. Fig. 81-90. Ontogenetic interpretations of normal, peltate and diplophyllous phyllomes. Fig. 81. Normal phyllomes. The only blade extends laterally, while growing in thickness. Fig. 82. Peltate phyllome, the two edges of the preceding blade have fused ventrally. Fig. 83. Same, but two growth centres, the first dorsal, the second ventral are involved in forming the leaf (see text). Fig. 84. Diplophyllous phyllomes, the two blades proliferate laterally as a whole. Fig. 85. Same but the two blades are separated. Fig. 86. As above, the two blades have met laterally. Fig. 87. Solid unifacial stalk of a peltate or diplophyllous phyllome. The growth trends of fig. 83 or 86 are assumed to be still effective. Fig. 88. In a diplophyllous phyllome the two blades grow as a whole, but the posterior one more rapidly than the other. Fig. 89. The posterior blade has thus fused its margins ventrally, the anterior blade is about to begin a similar process (dashed anows). See text. Fig. 90. Solid unifacial stalk of such a phyllome. The same growth trends are assumed to be involved. Same letters. The arrows indicate the progress of the blades, involving more and cells from the apex.

Stamen-carpel Homologies

205

met the carpel grows as a tore (fig. 83). This occurs in Drimys winteri and lanceolata (TUCKER 1969; TUCKER and GIFFORD 1966) as well as in Pseudowintera (SAMPSON 1963) and Hedycarya (SAMPSON 1969). Assuming now that the two blades in the last instance grow while remaining nearly flat and appressed and that their edges meet relatively late, the diplophyllous anther will be obtained (fig. 84). After the margins have met, the solid unifacial filament will be able to develop (fig. 87). In structures intermediate between stamen and carpel the two blades might form a closed cavity (fig. 85-86) before the filament begins developing, as in Tofieldia stamen-carpels. In many instances, in fact, both blades probably grow upon an unifacial sole, as in a peltate carpel (BAUM 1949). The processes alluded to occur therefore upon the filament as on the young unifacial stalk of the carpel. If the posterior blade grows at a more rapid pace than the anterior one, it will soon outstrip it on both sides (fig. 88) and may afterwards draw its two margins near each other ventrally in the same fashion as the single blade of a peltate carpel (fig. 89). It is clear that the cellular wings leading to this enwrapping of the anterior blade are superimposed with respect to the tissue of a normal diplophyllous stamen; they correspond perfectly to the hatched strips in fig. 58 and 61. To allow for the isolation and carrying upwards of the anterior blade (fig. 61, 65) it must be assumed that from a certain moment onwards the longitudinal growth of the anterior blade, be it through meresis or auxesis, is discontinued at least basally while the lengthening of the posterior blade continues, thus upheaving the anterior blade. Before or during the process the latter may also bring its margins near each other ventrally and fuse them. The funnel-shaped ventral blade will then appear after closure. In such intermediate stages as those described in Narcissus (fig. 57), the anterior blade may fuse its edges submarginally, the send out its both margins proper, now growing as a whole, so that they meet then fusion line of the posterior blade margins (fig. 89). The result is the two-pocketed structure of the upper connective and lower anther described above. Finally, as with the carpellary blade of fig. 83, the tore-shaped posterior blade may result from the delayed fusion of two opposite blade, after broadening. The free portion of the front blade, formed before fusion with the main one, will be the dual placental appendage (fig. 7, 66) or the front lobe of the Narcissus petaloid stamen (hatched on fig. 61). Two anterior growth centres may also exist and give birth to two placental lobes, finally fusing with each other and the main posterior blade. Another possibility i~ that the anterior blade is at first continuous and that two appendages then develop upon its edge, as leaflets on a compound leaf rachis. In plants belonging to the Sempervivum type, anterior blade initiation is omitted in the carpel, while the posterior blade stretches a little more beyond the lines along which posterior pollen sacs would be located in a stamen and produces the ovules.

206

M. GUEDES

This extension proceeds in such a way that the two margins approach each other and on occasion fuse congenitally to give birth to a peltate carpel. Teratologically the superimposed ovuliferous strips may grow freely at least in part as placental appendages (their free portion, however, is not the ovuliferous one when they have been seen partly free). They may also be partly free from the main blade and fertile at their free levels in some normal carpels (Caryophyllaceae). If the stamen has a first-initiated unifacial filament and the corresponding carpel is not peltate, the unifacial filament will be omitted at the beginning of carpel development, as in Sempervivum. In the Tofieldia type, on the other hand, the continuity of the whole phyllome is regained in the carpel, that is, one passes from the ontogeny of fig. 84 or 85 to that of fig. 82 with the margins meeting ventrally after having bounded a long ventral split which will become ovuliferous. All these various growth directions may be looked upon as involved in producing the solid filament (fig. 90) or the latter may develop as a whole before inception of those growth trends which will lead to the upper part of the intermediary or normal phyllome. Since sexual leaves are made up of parallel rows of cells, pollen sacs need not be always marginal. They are mostly so, but may become submarginal or be incorporated in the wall of a tore in stamen-carpels. A longitudinal intercalary row of cells may therefore· be sexualized while the neighbouring distal one still remains sterile. The stamen of the Coniferae is not diplophyllous and exhibits dorsal laminal pollen sacs which are probably to be accounted for in this way. Doubtless the cell rows in all phyllomes also have something to do with the telomes from which leaves hav\' probably arisen; they might represent telome trusses, some of which could be fertile and bear nucelli or pollinic units (GUEDES 1966a), thus producing ovular rows or pollen sacs. Modern concepts about foliage leaf ontogeny are able to account for gross morphology and ontogeny very well. The task remains of ascertaining them with respect to sexual phyllomes by indirect methods and, if possible, direct histological study. Literature AUBERT, P. L.: Organogenie de la £leur dans Ie genre Salix. Adansonia 11, 183-186 (1876). BARTELS, F.: Zur Entwicklung der Keimp£lanze von Epilobium hirsutum II. Flora 149, 225-242 (1960). IhuM, H.: Beitriige zur Kenntnis der Schildform bei den Staubbliittern. Oest. bot. Zeitschr. 96, 453-466 (1949). _ Die Bedeutung der diplophyllen Ubergangsblatter fiir den Rau der Staubblatter. Oest. bot. Zeitschr. 99, 228-243 (1952). Die Unabhangigkeit der diplophyllen Gestalt der Staubblattspreite von ihrer Funktion als Trager der Pollensacke. Oest. bot. Zeitschr. 100, 265-269 (1953).

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207

LEINFELLNER, W.: Die ontogenetischen Abanderungen des diplophyllen Grundbaues der Staubblatter. Oest. bot. Zeitschr. 100, 91-135 (1953). BEARD, B. H.: Estimating the number of meristem initials after seed irradiation: a method, applied to flax stems. Radiation Bot. 10,47-57 (1970). CELAKOVSKY, L. J.: Uber die Bedeutung und der Ursprung der Parakorolle der Narcisseen. Bull. intern. Acad. Sc. Emper. Fr.-Jos. Sc. math. nat. 6, 1-14 (1898). CROOKS, D. M.: Histological and regenerative studies on the flax seedling. Bot. Gaz. 96, 209-239 (1933). DULIEU, H.: Emploi des chimeres chlorophyliennes pour l'etude de l'ontogenie foliaire. Bull. scient. Bourgogne 26, 13-72 (1967 -1968). Dupuy, P.: Contribution Ii quelques problemes de morphologie et de teratologie ... chez les Angiospermes. Thesis. Poitiers (France) (1963). E.\MES, A. J.: The vascular anatomy of the flower. Amer. J. Bot. 18, 147-188 (1931). EBER, E.: Karpellbau und Plazentationsverhaltnisse in der Reihe der Helobiae. Flora 126, 273330 (1932). FISHER, M. J.: The morphology and anatomy of the flowers of the Salicaceae. Amer. J. Bot. 11), 307-326,372-394 (1928). FLORIN, R.: Evolution in Cordaites and Conifers. Acta Horti Bergiani 11),285-388 (1951). Gl'IlDES, M.: Sur la morphologie des stamino-carpelles. C. R. Acad. Sc. Paris 260, 2064-2067 (1965a). Homologies des pieces florales chez Tulipa gesneriana. Rev. gen. Bot., 72, 289-334 (1965b). L'etamine extrorse de I'Escholtzia californica Cham. C. R. Acad. Sc. Paris 261, 777-780 (1965 c). Stamen, carpel and ovule. The teratological approach to their interpretation. Adv. Front. PI. Sc. (Delhi) 14, 43-108 (1966a). Homologies du carpelle et de retamine chez Tulipa gesneriana. Oest. Bot. Zeitschr. 113, 47-83 (1966b). Stamen, tepal and corona in f.:arcissus. Adv. Front. PI. Sc. (Delhi) 16, 113-136 (1966c). RMlexions sur la notion de carpelle pelte. Beitr. BioI. Pflanzen 42,393-423 (1966d). Homologies de l'etamine et dn carpelle chez Veronica subsessilis (Miq.) Carr. Bot. Jahrb. 88, 382-409 (1968). La theorie de la metamorphose en morphologie vegetale. Des origines a Goethe et Batsch. Rev. Hist. Sr. Appl. 22, 323-363 (1969 a). Homologies de retamine et du carpelle chez Papaver orientale. C. R. Acad. SC'. Paris D 268. 926-929 (1969b). Contribution it la morphologie dn phyllome. Cellule 67, 341-365 (1969c). Nouvelles remarqnes sur l'architecture de la feuille. C. R. Acad. Sc. Paris D, 268, 2179-2181 (1969d). Un probleme de morphologie vegetale. La pomme de Pin. Sciences (Paris) 10, 39-44 (1970a). Le gynecee de quelques Bignoniacees ... Phyton 14, 147-163 (1970b). Carpel peltation and syncarpy in Coria ria ruscifolia L. New Phytol. 70, 213-227 (1971). Dupuy, P.: Degradation des caracteres diplophylle et pelte dans les pieces hermaphrodites de Sempervivum tectorum L. Bull. Soc. bot. Fr. 110, 282-296 (1963). - Further remarks on the leaflet theory of the ovule. New Phytol. 69, 1081-1091 (1970) . - Morphology of the seed-scale complex in Pinus pinaster. Phytomorphology, in press (1971). HAMANN, U.: Morphologische Beobachtungen an Hebe diosmifolia (Scrophulariaceae), besonders ihren Infloreszenzen. Bot. Jahrb. 79, 405-427 (1960).

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M. GUEDES, Stamen-cnrpel Homologies

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