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Pollen morphology and taxonomy of Cuphea (Lythraceae)
Review of Palaeobotany and Palynology Elsevier Publishing Company, Amsterdam - Printed in The Netherlands
POLLEN MORPHOLOGY AND TAXONOMY OF CUPHEA (LYTHRACEAE) ALAN GRAHAM AND SHIRLEY A. GRAHAM
Department of Biological Sciences, Kent State University, Kent, Ohio (U.S.A.) (Received August 28, 1966)
SUMMARY
The genus Cuphea is the largest and evolutionarily the most advanced member of the Lythraceae. Approximately 490 names have been applied, but Cuphea is in need of revision, and it is estimated there are about 260 valid species. A survey of Cuphea pollen reveals that the genus is eurypalynous. From 125 species examined, several pollen categories are recognized, including diporate grains from nine species reported here for the first time. The remaining species are oblate, tricolporate, tectate, commonly striate, and often syncolpate. Among the taxonomic conclusions that may be derived from a study of the pollen there are the following: Cuphea pseudosilene pollen is distinctly different from other members of the Section Brachyandra, Subsection Melanium, and more closely compares to C. parsonsia of the Subsection Balsamonella. Cuphea aperta and C. micrantha have pollen similar to members of the Section Trispermum, rather than other members of their present Section Braehyandra. Section Euandra, Subsection Oidemation is heterogeneous in pollen types, and probably does not represent a natural assemblage. Pollen size and morphology has demonstrated hybrids between C. wrightii subsp, wrightiiand C. wrightii subsp, compacta. These and other data are proving useful in the revision currently underway of this difficult genus.
INTRODUCTION
The genus Cuphea is the largest, and evolutionarily the most advanced member of the Lythraceae. It is a complex assemblage as reflected in the only monograph, by KOEI-mE(1903). Approximately 490 names have been proposed, of which about 260 represent valid species. Taxonomic studies are complicated by the fact that an estimated 91 of the 260 species are known only from the type locality or type specimen, and a large portion of Koehne's Lythraceae collection in the Berlin Herbarium was destroyed. Until recently no valid chromosome counts Rev. Palaeobotan. Palynol., 3 (1967) 155-162
155
were available for any of the 490 names. Genetic studies are difficult because the stamens dehise while tile flower is still in bud, the chromosome number is relatively large (up to ca.84), and the chromosomes are minute in size (1 ,u in diameter). Anatomically the species are similar, and the complex floral morphology has not been sufficiently studied. As a consequence of these difficulties, characters which vary consistently among the taxa are of unusual significance from the standpoint of taxonomy. One such character is the morphology of the pollen, and at present 125 species have been studied.
MATERIALS AND METHODS
Pollen was collected from herbarium sheets and is vouchered in one of several herbaria (MICH, US, GH, AA). The pollen was processed by the KOH-acetolysis technique, mounted unstained in glycerine jelly, and sealed with diaphane. The photographs were taken at 40 x magnification using a Wild microscope and Nikon 35 mm camera with didynium filter. The terminology followed is that of FAEGRXand IVERSEN (1964).
THE MORPHOLOGY OF CUPHEA POLLEN
The pollen of Cuphea is sufficiently varied that no one type is representative of the genus. In general, there are two basic categories, diaperturate and triaperturate. Diaperturate pollen, reported here for the first time, is found in 9 species of the 125 species studied: C. affinitatum, costata, glutinosa, ingrata, lutescens, persistens, prunellifolia, thymoides, and tuberosa. Within this group there is little variation in pollen morphology, and C. costata (Plate I, 1, 2) is taken as an example of the diaperturate type: Prolate (body varying to spherical, excluding protruding pores), oval-triangular to nearly circular in polar view; diporate, pores polar, circular, ca 5.5 # in diameter, protruding ca. 3.5 # beyond margin of grain, endexine extending only slightly into protruding part of pore, margin
PLATE 1 Pollen grains of Cuphea. l, 2. C. costata. 3. C. ferrisiae. 4. C. anagalloides. 5, 6. C. longiflora. 156
7. 8. 9. 10.
C. C. C. C.
infundibulum. aperta. micrantha. ramulosa.
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
PLATE I
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
157
entire, pores connected by three colpi, meridionally elongated, straight, equidistant, broad (7--9 #) at equator, tapering toward poles, 7-8 # long (pole to equator), margo present (2-3 # wide), margo margin straight, entire; striate, striae oriented horizontally between colpi, slightly sinuous, moderately fine (ca. 0.5- I /t wide); tectate; size: 27 x 19/~, including protruding pores. Triaperturate pollen is more c o m m o n , being represented by 116 o f the 125 species studied. The pollen o f C. ferrisiae is used as an example, but because of the large number of species with triaperturate pollen, four additional categories are used to demonstrate the variation within this basic type. Cuphea ferrisiae is described below and illustrated on Plate 1,3: Oblate, triangular to oval-triangular in polar view; tricolporate, colpi straight, tapering to an acute apex, meridionally elongated, equidistant, margin entire, polar index 9:32, pores equatorially arranged, situated at the mid-point of the colpi, aspidate, margin entire; exine with 2-3 coarse striae on either side of the pores, striae length ca. 7 #, width ca. 1 /~, height ca. I #, broader at the base and tapering to a rounding apex, producing a coarse lobate appearance in polar view about the pores, absent from remainder of grain, extending at an angle toward, but not intersecting colpi; psilate (other than areas of coarse striae); tectate; size: 32 #. Variations on the type described above are illustrated by the following four categories o f Cuphea pollen.
Group I C. anagalloides (Plate I, 4) mimuloides. The pollen o f this group is small (ca. 25 /z), psilate, and tricolporate. Two c o m m o n features o f Cuphea pollen, protruding pores and syncolpi, are absent, and these grains form a natural and distinct group that parallels the taxonomic treatment based primarily on floral morphology. Group H C. bombonasae, bonplandii, calophylla, ciliata, cordifolia (Plate II, 3), decandra, denticulata, epilobifolia, flavisetula, fruticosa, gaumeri, longiflora (Plate I, 5, 6), melanium, racemosa, repens, salicifolia, rotundifolia, serpyllifolia (Plate II, 4), setosa, sordida, tetrapetala (Plate II, 1,2), urens, utriculosa. These grains
P L A T E II Pollen grains of Cuphea. 1, 2. C. tetrapetala.
9. C. lysimachiodes.
3. 4. 5. 6.
C. cordifolia. C. serpyllifolia, C. pseudosilene. C. parsonsia.
10. C. wrightiiintermediate; abnormal tetraporate grain. 11. C. wrightiisubsp, wrightii. 12. C. wrightiiintermediate.
7.
C. tuberosa.
13. C. wrightii subsp, compacta.
8.
C. aspera.
158
Rev. Palaeobotan. PalynoL, 3 (1967) 155-162
PLATE II
Rev. Palaeobotan. PalynoL, 3 (1967) 155-162
159
are similar to Group I, but differ in having a rugulate sculpture pattern. Theyalso parallel the taxonomy proposed by KOEnNE (1903), and are found in the Sections Enantiocuphea, Heteranthus, and Brachyandra, Subsections Microcuphea and Melanium. The present placement of C. pseudosilene (Plate II, 5) in the Subsection Melanium will be considered later in the discussion of taxonomic groupings.
Group 111 C. aequipetala, appendiculata, avigera, bustamanta, caeciliae, cordata, cyanea, empetrifolia, graciliflora, heterophylla, hookeriana, ianthina, imberbis' infundibulum (Plate I, 7), ixodes, jorullensis, koehneana, micropetala, nitidula, painteri, palustris, paucipetala, pinetorum, scaberrima, watsoniana. This group is characterized by pollen with non-protruding or only slightly protruding pores, and moderately fine striations that uniformly cover the surface of the grain. Within this group there are variations, particularly in size (small, ca. 25 /~ to large, ca. 40/~) and shape as seen in polar view (distinctly triangular to ovaltriangular), but in most other characters the pollen is similar. It is interesting that C. boisserriana of the Section Leptocalyx, and C. retroscabra of the Section Melvilla, Subsection Erythrocalyx, has pollen distinctly different from other members of its group.
Group IV C. anisoclada, aperta (Plate I, 8), ericoides, tiara, micrantha (Plate I, 9), ramulosa (Plate I, 10). The pollen of this group is psilate and syncolpate, with protruding apertures. The distinctive character is the presence of interaperturate thickenings. The six species occur in the Sections Brachyandra (2 species), and Trispermum (4 species). POLLEN MORPHOLOGY AND TAXONOMY
Pollen morphology has proven a valuable taxonomic character in Cuphea. Following are four examples of the use of pollen data in evaluating the present taxonomic groupings. (1) Position of spectes within subgeneric categories. Pollen from seven of the 10 species of the Section Brachyandra, Subsection Melanium was studied. Six of these are similar, being small, rugulate, with non-protruding pores and lacking syncolpi. The pollen of C. pseudosilene (Plate II, 5) is distinctly different, however, and does not belong to the same pollen category (i.e., C. tetrapetala, cordifolia, serpyllifolia; Plate II, 1-4). A survey of other species reveals that pollen of C. pseudosilene is similar to C. parsonsia (Plate II, 6) of the Subsection Balsamonella. The floral morphology 160
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
is also similar. For example, C. pseudosilene differs from other members of the Subsection Melanium in having six rather than eleven stamens. In this respect it resembles C. parsonsia. Thus, pollen data, in conjunction with floral morphology, suggests that C. pseudosilene is more closely related to C. parsonsia than to members of its present Subsection. The pollen of species in the Section Trispermum (C. anisoclada, ericoides, flava, ramulosa; Plate I, 10) is characterized by interaperturate thickenings. Since this is a relatively unique character, occurring in only 7 species of the 125 species examined, it probably reflects a close taxonomic relationship among members of the Section Trispermum. According to KOEHNE (1903), the species of the section are frequently difficult to distinguish on the basis of floral morphology, are variable, and connected by intermediate forms, thus supporting the contention that species in Section Trispermum are a natural and closely related group of plants. Two species in the Section Brachyandra (C. aperta, micrantha; Plate I, 8, 9), however, also have these unique interaperturate thickenings. Consequently, there is need to determine if C. aperta and C. micrantha should not belong in the Section Trispermum. (2) Naturalness and interrelationship of sections. A number of sections proposed by Koehne are natural from the standpoint of pollen morphology. For example, all the pollen studied of the Section Pseudocircaea are diporate. Similarly, species in the Sections Heteranthus, Enantiocuphea, and Brachyandra, Subsection Melanium (except C. pseudosilene) have the same general pollen type and belong to one large natural group. (3) Unnatural subgeneric groupings. The Section Euandra, Subsection Oidemarion is heterogeneous with regards to pollen. It is interesting that this is the last subsection described by Koehne and appears to contain a diverse assemblage of species difficult to place in other groups. For example, C. tuberosa (Plate II, 7) is diporate; C. aspera (Plate II, 8) is psilate and syncolpate, with conspicuously protruding pores, and compares to no other pollen studied; C. confertiJblia, lysimachiodes (Plate II, 9), and retroscabra have coarse striations on either side of the pore, and are syncolpate. The latter compare most closely to pollen in the Section Euandra, Subsection Platypterus. These data indicate a need for redefinition of the Subsection Oidemation. (4) Polyploidy and hybridization. Cuphea wrightii has been studied cytologically, and consists of two subspecies wrightii (n ~ I0) and compacta (n : 12). The hybrids are allotetraploids (n ~-- 22). The pollen of these subspecies are distinct. Cuphea wrightii subsp, compacta (Plate II, 13) has striations only on either side of the pore, while in subsp, wrightii (Plate II, 11) the striations are larger on either side of the pore, but also occur along the intervening areas. The size of both is 30 /z. The pollen of the hybrids (Plate II, 12) was studied, and found to be Rev. Palaeobotan. Palynol., 3 (1967) 155-162
161
larger (36 /z) than the parents (30 fz), following a c o m m o n pattern of increased pollen size with increased state of ploidy. There were also abnormal, tetraporate grains (Plate II, 10), reflecting meiotic irregularity. Finally, the pollen, although tending toward one or the other parent, combined the characters o f both. Pollen data has, therefore, substantiated hybridization and polyploidy in these species of Cuphea.
REFERENCES ERDTMAN,G., 1952. Pollen Morphology and Plant Taxonomy (An Introduction to Palynology, l). Chronica Botanica Co., Waltham, Mass., pp. 252-253. FAEGR1,K. and IEVERSEN,J., 1964. Textbook of Pollen Analysis. Munksgaard, Copenhagen/Blackwells, Oxford, 2 ed., 237 pp. KOEHNE,E., 1903. Lythraceae. In: A. EN~LER (Herausgeber), Das Pflanzenreich. Engelmann, Weinheim, 4(216): 326 pp.; Cuphea, pp. 80-179. SALGADO-LABOURIEAU,M. L. and MARQUESVALIO, L F., 1964. Pollen grains of plants of the "Cerrado", 8. Lythraceae. Rev. Brasil Biol., 24: 439~,50.
162
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
POLLEN MORPHOLOGY AND TAXONOMY OF CUPHEA (LYTHRACEAE) ALAN GRAHAM AND SHIRLEY A. GRAHAM
Department of Biological Sciences, Kent State University, Kent, Ohio (U.S.A.) (Received August 28, 1966)
SUMMARY
The genus Cuphea is the largest and evolutionarily the most advanced member of the Lythraceae. Approximately 490 names have been applied, but Cuphea is in need of revision, and it is estimated there are about 260 valid species. A survey of Cuphea pollen reveals that the genus is eurypalynous. From 125 species examined, several pollen categories are recognized, including diporate grains from nine species reported here for the first time. The remaining species are oblate, tricolporate, tectate, commonly striate, and often syncolpate. Among the taxonomic conclusions that may be derived from a study of the pollen there are the following: Cuphea pseudosilene pollen is distinctly different from other members of the Section Brachyandra, Subsection Melanium, and more closely compares to C. parsonsia of the Subsection Balsamonella. Cuphea aperta and C. micrantha have pollen similar to members of the Section Trispermum, rather than other members of their present Section Braehyandra. Section Euandra, Subsection Oidemation is heterogeneous in pollen types, and probably does not represent a natural assemblage. Pollen size and morphology has demonstrated hybrids between C. wrightii subsp, wrightiiand C. wrightii subsp, compacta. These and other data are proving useful in the revision currently underway of this difficult genus.
INTRODUCTION
The genus Cuphea is the largest, and evolutionarily the most advanced member of the Lythraceae. It is a complex assemblage as reflected in the only monograph, by KOEI-mE(1903). Approximately 490 names have been proposed, of which about 260 represent valid species. Taxonomic studies are complicated by the fact that an estimated 91 of the 260 species are known only from the type locality or type specimen, and a large portion of Koehne's Lythraceae collection in the Berlin Herbarium was destroyed. Until recently no valid chromosome counts Rev. Palaeobotan. Palynol., 3 (1967) 155-162
155
were available for any of the 490 names. Genetic studies are difficult because the stamens dehise while tile flower is still in bud, the chromosome number is relatively large (up to ca.84), and the chromosomes are minute in size (1 ,u in diameter). Anatomically the species are similar, and the complex floral morphology has not been sufficiently studied. As a consequence of these difficulties, characters which vary consistently among the taxa are of unusual significance from the standpoint of taxonomy. One such character is the morphology of the pollen, and at present 125 species have been studied.
MATERIALS AND METHODS
Pollen was collected from herbarium sheets and is vouchered in one of several herbaria (MICH, US, GH, AA). The pollen was processed by the KOH-acetolysis technique, mounted unstained in glycerine jelly, and sealed with diaphane. The photographs were taken at 40 x magnification using a Wild microscope and Nikon 35 mm camera with didynium filter. The terminology followed is that of FAEGRXand IVERSEN (1964).
THE MORPHOLOGY OF CUPHEA POLLEN
The pollen of Cuphea is sufficiently varied that no one type is representative of the genus. In general, there are two basic categories, diaperturate and triaperturate. Diaperturate pollen, reported here for the first time, is found in 9 species of the 125 species studied: C. affinitatum, costata, glutinosa, ingrata, lutescens, persistens, prunellifolia, thymoides, and tuberosa. Within this group there is little variation in pollen morphology, and C. costata (Plate I, 1, 2) is taken as an example of the diaperturate type: Prolate (body varying to spherical, excluding protruding pores), oval-triangular to nearly circular in polar view; diporate, pores polar, circular, ca 5.5 # in diameter, protruding ca. 3.5 # beyond margin of grain, endexine extending only slightly into protruding part of pore, margin
PLATE 1 Pollen grains of Cuphea. l, 2. C. costata. 3. C. ferrisiae. 4. C. anagalloides. 5, 6. C. longiflora. 156
7. 8. 9. 10.
C. C. C. C.
infundibulum. aperta. micrantha. ramulosa.
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
PLATE I
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
157
entire, pores connected by three colpi, meridionally elongated, straight, equidistant, broad (7--9 #) at equator, tapering toward poles, 7-8 # long (pole to equator), margo present (2-3 # wide), margo margin straight, entire; striate, striae oriented horizontally between colpi, slightly sinuous, moderately fine (ca. 0.5- I /t wide); tectate; size: 27 x 19/~, including protruding pores. Triaperturate pollen is more c o m m o n , being represented by 116 o f the 125 species studied. The pollen o f C. ferrisiae is used as an example, but because of the large number of species with triaperturate pollen, four additional categories are used to demonstrate the variation within this basic type. Cuphea ferrisiae is described below and illustrated on Plate 1,3: Oblate, triangular to oval-triangular in polar view; tricolporate, colpi straight, tapering to an acute apex, meridionally elongated, equidistant, margin entire, polar index 9:32, pores equatorially arranged, situated at the mid-point of the colpi, aspidate, margin entire; exine with 2-3 coarse striae on either side of the pores, striae length ca. 7 #, width ca. 1 /~, height ca. I #, broader at the base and tapering to a rounding apex, producing a coarse lobate appearance in polar view about the pores, absent from remainder of grain, extending at an angle toward, but not intersecting colpi; psilate (other than areas of coarse striae); tectate; size: 32 #. Variations on the type described above are illustrated by the following four categories o f Cuphea pollen.
Group I C. anagalloides (Plate I, 4) mimuloides. The pollen o f this group is small (ca. 25 /z), psilate, and tricolporate. Two c o m m o n features o f Cuphea pollen, protruding pores and syncolpi, are absent, and these grains form a natural and distinct group that parallels the taxonomic treatment based primarily on floral morphology. Group H C. bombonasae, bonplandii, calophylla, ciliata, cordifolia (Plate II, 3), decandra, denticulata, epilobifolia, flavisetula, fruticosa, gaumeri, longiflora (Plate I, 5, 6), melanium, racemosa, repens, salicifolia, rotundifolia, serpyllifolia (Plate II, 4), setosa, sordida, tetrapetala (Plate II, 1,2), urens, utriculosa. These grains
P L A T E II Pollen grains of Cuphea. 1, 2. C. tetrapetala.
9. C. lysimachiodes.
3. 4. 5. 6.
C. cordifolia. C. serpyllifolia, C. pseudosilene. C. parsonsia.
10. C. wrightiiintermediate; abnormal tetraporate grain. 11. C. wrightiisubsp, wrightii. 12. C. wrightiiintermediate.
7.
C. tuberosa.
13. C. wrightii subsp, compacta.
8.
C. aspera.
158
Rev. Palaeobotan. PalynoL, 3 (1967) 155-162
PLATE II
Rev. Palaeobotan. PalynoL, 3 (1967) 155-162
159
are similar to Group I, but differ in having a rugulate sculpture pattern. Theyalso parallel the taxonomy proposed by KOEnNE (1903), and are found in the Sections Enantiocuphea, Heteranthus, and Brachyandra, Subsections Microcuphea and Melanium. The present placement of C. pseudosilene (Plate II, 5) in the Subsection Melanium will be considered later in the discussion of taxonomic groupings.
Group 111 C. aequipetala, appendiculata, avigera, bustamanta, caeciliae, cordata, cyanea, empetrifolia, graciliflora, heterophylla, hookeriana, ianthina, imberbis' infundibulum (Plate I, 7), ixodes, jorullensis, koehneana, micropetala, nitidula, painteri, palustris, paucipetala, pinetorum, scaberrima, watsoniana. This group is characterized by pollen with non-protruding or only slightly protruding pores, and moderately fine striations that uniformly cover the surface of the grain. Within this group there are variations, particularly in size (small, ca. 25 /~ to large, ca. 40/~) and shape as seen in polar view (distinctly triangular to ovaltriangular), but in most other characters the pollen is similar. It is interesting that C. boisserriana of the Section Leptocalyx, and C. retroscabra of the Section Melvilla, Subsection Erythrocalyx, has pollen distinctly different from other members of its group.
Group IV C. anisoclada, aperta (Plate I, 8), ericoides, tiara, micrantha (Plate I, 9), ramulosa (Plate I, 10). The pollen of this group is psilate and syncolpate, with protruding apertures. The distinctive character is the presence of interaperturate thickenings. The six species occur in the Sections Brachyandra (2 species), and Trispermum (4 species). POLLEN MORPHOLOGY AND TAXONOMY
Pollen morphology has proven a valuable taxonomic character in Cuphea. Following are four examples of the use of pollen data in evaluating the present taxonomic groupings. (1) Position of spectes within subgeneric categories. Pollen from seven of the 10 species of the Section Brachyandra, Subsection Melanium was studied. Six of these are similar, being small, rugulate, with non-protruding pores and lacking syncolpi. The pollen of C. pseudosilene (Plate II, 5) is distinctly different, however, and does not belong to the same pollen category (i.e., C. tetrapetala, cordifolia, serpyllifolia; Plate II, 1-4). A survey of other species reveals that pollen of C. pseudosilene is similar to C. parsonsia (Plate II, 6) of the Subsection Balsamonella. The floral morphology 160
Rev. Palaeobotan. Palynol., 3 (1967) 155-162
is also similar. For example, C. pseudosilene differs from other members of the Subsection Melanium in having six rather than eleven stamens. In this respect it resembles C. parsonsia. Thus, pollen data, in conjunction with floral morphology, suggests that C. pseudosilene is more closely related to C. parsonsia than to members of its present Subsection. The pollen of species in the Section Trispermum (C. anisoclada, ericoides, flava, ramulosa; Plate I, 10) is characterized by interaperturate thickenings. Since this is a relatively unique character, occurring in only 7 species of the 125 species examined, it probably reflects a close taxonomic relationship among members of the Section Trispermum. According to KOEHNE (1903), the species of the section are frequently difficult to distinguish on the basis of floral morphology, are variable, and connected by intermediate forms, thus supporting the contention that species in Section Trispermum are a natural and closely related group of plants. Two species in the Section Brachyandra (C. aperta, micrantha; Plate I, 8, 9), however, also have these unique interaperturate thickenings. Consequently, there is need to determine if C. aperta and C. micrantha should not belong in the Section Trispermum. (2) Naturalness and interrelationship of sections. A number of sections proposed by Koehne are natural from the standpoint of pollen morphology. For example, all the pollen studied of the Section Pseudocircaea are diporate. Similarly, species in the Sections Heteranthus, Enantiocuphea, and Brachyandra, Subsection Melanium (except C. pseudosilene) have the same general pollen type and belong to one large natural group. (3) Unnatural subgeneric groupings. The Section Euandra, Subsection Oidemarion is heterogeneous with regards to pollen. It is interesting that this is the last subsection described by Koehne and appears to contain a diverse assemblage of species difficult to place in other groups. For example, C. tuberosa (Plate II, 7) is diporate; C. aspera (Plate II, 8) is psilate and syncolpate, with conspicuously protruding pores, and compares to no other pollen studied; C. confertiJblia, lysimachiodes (Plate II, 9), and retroscabra have coarse striations on either side of the pore, and are syncolpate. The latter compare most closely to pollen in the Section Euandra, Subsection Platypterus. These data indicate a need for redefinition of the Subsection Oidemation. (4) Polyploidy and hybridization. Cuphea wrightii has been studied cytologically, and consists of two subspecies wrightii (n ~ I0) and compacta (n : 12). The hybrids are allotetraploids (n ~-- 22). The pollen of these subspecies are distinct. Cuphea wrightii subsp, compacta (Plate II, 13) has striations only on either side of the pore, while in subsp, wrightii (Plate II, 11) the striations are larger on either side of the pore, but also occur along the intervening areas. The size of both is 30 /z. The pollen of the hybrids (Plate II, 12) was studied, and found to be Rev. Palaeobotan. Palynol., 3 (1967) 155-162
161
larger (36 /z) than the parents (30 fz), following a c o m m o n pattern of increased pollen size with increased state of ploidy. There were also abnormal, tetraporate grains (Plate II, 10), reflecting meiotic irregularity. Finally, the pollen, although tending toward one or the other parent, combined the characters o f both. Pollen data has, therefore, substantiated hybridization and polyploidy in these species of Cuphea.
REFERENCES ERDTMAN,G., 1952. Pollen Morphology and Plant Taxonomy (An Introduction to Palynology, l). Chronica Botanica Co., Waltham, Mass., pp. 252-253. FAEGR1,K. and IEVERSEN,J., 1964. Textbook of Pollen Analysis. Munksgaard, Copenhagen/Blackwells, Oxford, 2 ed., 237 pp. KOEHNE,E., 1903. Lythraceae. In: A. EN~LER (Herausgeber), Das Pflanzenreich. Engelmann, Weinheim, 4(216): 326 pp.; Cuphea, pp. 80-179. SALGADO-LABOURIEAU,M. L. and MARQUESVALIO, L F., 1964. Pollen grains of plants of the "Cerrado", 8. Lythraceae. Rev. Brasil Biol., 24: 439~,50.
162
Rev. Palaeobotan. Palynol., 3 (1967) 155-162