1 Taxonomy

Biology of Brassica Coenospecies C. G6mez-Campo (Editor) 9 1999 Elsevier Science B.V. All rights reserved.

TAXONOMY C6sar G 6 m e z - C a m p o

Dept. Biologia Vegetal, Universidad Polit~cnica de Madrid. 28040 - Madrid. Spain. Coenospecies is not a t a x o n o m i c category b u t a cytogenetical concept whose taxonomic c o u n t e r p a r t could c o n s i s t of a g r o u p of "allies" or "relatives" to a given taxon. Here, it is applied to the species a n d s u b s p e c i e s of the g e n u s Brassica, together with those of its closest related genera. Where s h o u l d the limits be placed? Special e m p h a s i s is p u t on g e n e r a Erucastrum,

Diptotaxis, Hirschfeldia, Eruca, Sinapis, Sinapidendron, Coincya, Raphanus and Trachystoma, together with Brassica itself. However, a brief i n c u r s i o n into the rest of the tribe Brassiceae will cover o t h e r possible wild relatives. Some y e a r s ago, a book edited by T s u n o d a , H i n a t a a n d G 6 m e z - C a m p o (1980) was p u b l i s h e d with a similar scope to the p r e s e n t one. Almost two d e c a d e s later, trying to review new d e v e l o p m e n t s c o n c e r n i n g the t a x o n o m y of this group, p r o d u c e s a mixture of positive, negative a n d c o n f u s i n g feelings. On the one h a n d , a lot h a s been written on the s u b j e c t a n d references at the end of this article include only a part, t h a t t h o u g h t to be the m o s t significant, of all w h a t h a s been p r o d u c e d in this period. On the o t h e r h a n d , it is p e r h a p s too early to profit a d e q u a t e l y from the c o n t r i b u t i o n s t h a t cytogenetic a n d m o l e c u l a r m e t h o d s are m a k i n g to the knowledge of this botanical group as they do for m a n y others. In short, this book m a y be o p p o r t u n e as a whole, b u t a c h a p t e r on the t a x o n o m y of Brassica a n d allies would have benefited from being p o s t p o n e d p e r h a p s a decade or so to receive - a n d digest- f u r t h e r i n p u t s from o t h e r fast developing fields to become more useful a n d complete. A significant p a r t of recent w o r k on the t a x o n o m y of Brassica coenospecies is directly or indirectly related to a series of m o n o g r a p h i c t h e s e s which are worth listing together in advance" Baillargeon (1986) on Sinapis, Gladis (1989), E a s t w o o d (1996), Lann6r (1997) a n d Ls (1997) on Brassica, Leadlay (see Leadley a n d Heywood, 1990) on Coincya, Martinez-Laborde (1988a) on Diplotaxis, Pistrick (1987) on Raphanus, S a l m e e n (1979) on Brassica a n d S~nchez-Y61amo (1990) on the Diplotaxis-Erucastrum-Brassica complex. In addition to c u r r e n t literature a n d several new local floras, the publication of E u c a r p i a Cruciferae Newsletter h a s proved to be a positive factor in

s t i m u l a t i n g r e s e a r c h a n d c o m m u n i c a t i o n in this discipline a n d in m a n y ot h e r s related to Brassica. At the s a m e time, a n u m b e r of related w o r k s h o p s a n d meetings, periodic or not, at least in three c o n t i n e n t s , have also played a significant part. This c h a p t e r s t a r t s with a s h o r t reference to the already well known six cultivated species of the classical U-triangle (see c h a p t e r 3) to proceed to the wild relatives of Brassica oleracea, t h e n to the g e n u s Brassica as a whole, to its m o s t related g e n e r a and, finally, beyond the coenospecies limits, giving a few c o m m e n t s on the tribe Brassiceae as a whole. U p d a t e d s y n o p s e s are provided for the s u b g e n e r a , sections, species a n d s u b s p e c i e s of the ten genera m e n t i o n e d so far (Table 1.1) as well as for all the tribe g e n e r a (Table 1.2).

Cultivated B r a s s i c a species Regarding the infraspecific variability of B. oleracea, there is an unwritten a g r e e m e n t to describe this with t a x o n o m i c categories below the range of s u b s p e c i e s . This is r e a s o n a b l e b e c a u s e a l t h o u g h this variability is very high, it originated u n d e r d o m e s t i c a t i o n in a relatively s h o r t period of time. A detailed a c c o u n t is b e y o n d the scope of this c h a p t e r , b u t the r e a d e r is referred to Dickson a n d Wallace (1986) or to several articles grouped within the section "cole crops" in Kalloo a n d Berg (1993). A p r e l i m i n a r y information can be found in tables 10.1, 10.3 a n d 10.6 within the p r e s e n t book.

B. oleracea wild types are only truly wild along the E u r o p e a n Atlantic c o a s t s a n d t h e y have often been referred to var. sylvestris L. They are close to cultivated forms (Gustafsson a n d L a n n ~ r - H e r r e r a , 1997a) and almost morphologically i n d i s t i n g u i s h a b l e from m a n y kales. O t h e r so called "sylvestris" in other p a r t s of the world, are mere e s c a p e s from cultivation. Two o t h e r closely related t a x a originally c o n s i d e r e d as species, n a m e l y B. bourgeaui a n d B. alboglabra, s h o u l d p r o b a b l y merit an infraspecific s t a t u s within B. oleracea variation. B. bourgeaui, from the C a n a r y Islands, was included in the g e n u s Sinapidendron in early literature a n d t h o u g h t to be extinct for m a n y years. It was re-found by Borgen et al. (1979) who ascribed it to the n = 9 Brassica group. They only found two p l a n t s in La Palma Island. Today, m o s t opinions e m p h a s i z e its close relation to B. oleracea (Lann~r, 1998) t h o u g h , p e r h a p s , some possible differential c h a r a c t e r s in leaves a n d pod b e a k s s h o u l d be s t u d i e d more carefully. A second population h a s been found more recently (Marrero, 1989) in E1 Hierro Island. B. alboglabra, a n old cultivated form from China, h a s puzzled r e s e a r c h e r s for years bec a u s e of the p h y t o g e o g r a p h i c a l problem it poses. B o t h m e r et al. (1995) s u m marize the r e a s o n s w h y it s h o u l d be kept within B. oleracea. Although it h a d always been believed to have r e a c h e d C h i n a from the M e d i t e r r a n e a n region, conclusive evidence only a p p e a r e d w h e n H a m m e r et al. (1992) found it locally cultivated in S o u t h Italy. Flowers are n o r m a l l y white a l t h o u g h they m a y be yellow a n d they distinctively a p p e a r in early wintertime.

T a b l e 1 . 1 A t a x o n o m i c synopsis of B r a s s i c a and its allied genera with indication o f subgenera, sections, species and subspecies. B R A S S I C A L.

Subgen. Brassica Sect. Brassica B. oleracea L. B. montana Pourret B. incana Ten. subsp, incana B. i. subsp, cazzae (Ginz. and Teyb.) Trinajstic B. villosa Biv. subsp, villosa B. v. subsp, bivoniana (Mazzola and Raimondo) R.and M. B. v. subsp, drepanensis (Caruel) Raimondo and Mazzola B. v. subsp, tinei (Lojac.) Raimondo and Mazzola B. rupestris Rafin subsp, rupestris B. r. subsp, brevisiliqua Raimondo and Mazzola B. r. subsp, hispida Raimondo and Mazzola B. macrocarpa Guss. B. insularis Moris B. cretica Lam. subsp, cretica B. c. subsp, aegaea (Heldr. and Hal.) Snogerup et al. B. c. subsp, laconica Gustafsson and Snogerup B. botteri Vis. subsp, botteri B. b. subsp, mollis (Vis.) Trinajstic B. hilarionis Post. B. carinata Braun B. balearica Pets.

Sect. Rapa (Miller) Salmeen B. rapa L. subsp, rapa B. r. subsp, campestris (L.) Clapman B. r. subsp, chinensis (L.) Hanelt B. r. subsp, dichotoma (Roxb.) Hanelt B. r. subsp, narinosa (Bailey) Hanelt B. r. subsp, nipposinica (Bailey) Hanelt B. r. subsp, pekinensis (Lour.) Hanelt B. r. subsp, trilocularis (Roxb.) Hanelt B. napus L. B. juncea (L.) Czern.

Sect. Micropodium DC. B. fruticulosa Cyr. subsp, fruticulosa B. f subsp, djafarensis Blanco and Matarranz B . f subsp, dolichocarpa Emberger and Maire B . f subsp, glaberrima (Pomel) Maire

B. f subsp, mauritanica (Cosson) Maire B. f subsp, numidica Maire B. f subsp, pomeliana Maire B. f subsp, radicata (Desf.) Maire B. nigra (L.) Koch B. cossoniana Boiss. and Reuter B. spinescens Pomel B. maurorum Durieu B. procumbens (Poiret) O.E.Schulz B. cadmea O.E.Schulz B. desertii Danin and Hedge Sect. Brassicoides Boiss. B. deflexa Boiss.

Sect. Sinapistrum Willkomm B. barrelieri (L.) Janka B. oxyrrhina Coss. B. tournefortii Gouan

Sub~en. Brassicaria (Godr.) G6mez-Campo Sect. Brassicaria (Godr.) Cosson B. repanda (Willd.) DC. subsp, repanda B.r. subsp, africana (Maire) Greuter and Burdet B.r. subsp, almeriensis G6mez-Campo B.r. subsp, blancoana (Boiss.) Heywood B.r. subsp, cadevallii (Font Quer) Heywood B.r. subsp, cantabrica (Font Quer) Heywood B.r. subsp, confusa (Emb. and Maire) Heywood B.r. subsp, galissieri (Giraud) Heywood B.r. subsp, glabrescens (Poldini) G6mez-Campo B.r. subsp, gypsicola G6mez-Campo B.r. subsp, latisiliqua (Boiss. and Reut.) Heywood B.r. subsp, nudicaulis (Lag.) Heywood B.r. subsp, saxatilis (DC.) Heywood B.r. subsp, silenifolia (Emberger) Greuter and Burdet B. desnotesii Emb. and Maire B. gravinae Ten. B. jordanoffii O.E.Schulz B. loncholoma Pomel B. nivalis Boiss. and Heldr. B. elongata Ehrh. subsp, elongata B. e. subsp, integrifolia (Boiss.)Breistr. B. e. subsp, imdrahsiana Quezel B. e. subsp, pinnatifida (Smal'g) Greuter and Burdet B. e. subsp, subscaposa Maire and Weiller B. setulosa (Boiss. and Reuter) Cosson

B. somaliensis Hedge and Miller

Sect. Nasturtiops (Pomel) Salmeen B. souliei (Batt.) Batt. subsp, souliei B. s. subsp, amplexicaulis (Desf.) Greuter and Burdet B. dimorpha Coss. and Dur.

ERUCASTRUM C. Presl. E. gallicum O.E.Schulz E. nasturtiifolium (Poiret) O.E.Schulz subsp, nasturtiifolium E. n. subsp, sudrei Vivant E. leucanthum Coss. and Dur. E. palustre (Pir.) Vis. E. virgatum C.Presl. subsp, virgatum E. v. subsp, baeticum (Boiss.) G6mez-Campo E. v. subsp, brachycarpum (Rouy) G6mez-Campo E. v. subsp, pseudosinapis (Lange) G6mez-Campo E. varium Durieu subsp, varium E. v. subsp, mesatlanticum Maire and Wilczek E. v. subsp, subsiifolium Maire E. littoreum (Pau and F.Quer) Maire subsp, littoreum E. l. subsp, brachycarpum (Maire and Weiller)G6mez-Campo E. l. subsp, glabrum (Maire) G6mez-Campo E. rifanum (Emb. and Maire) G6mez-Campo E. elatum (Ball.) O.E.Sehulz E. brevirostre (Maire) G6mez-Campo E. canariense Webb and Berth. E. cardaminoides (Webb ex Christ.) O.E.Schulz E. ifniense G6mez-Campo E. arabicum Fisch. and Mey. E. elgonense Jonsell E. meruense Jonsell E. abyssinicum (A. Rich.) O.E.Schulz E. pachypodum (Chiov.) Jonsell E. rostratum (Balf. f.)G6mez-Campo E. strigosum (Thunb.) O.E.Schulz E. griquense (Brown) O.E.Schulz DIPL 0 TAXIS D C.

Subgen. Diplotaxis D. tenuifolia (L.)DC. subsp, tenuifolia D. t. subsp, cretacica (Kotov)Sobrino-Vesperinas D. muralis (L.) DC. subsp, muralis D. m. subsp, ceratophylla (Batt.) Mart.-Lab. D. viminea (L.) DC. D. simplex (Viv.) Spr.

Subgen. Hesperidium (DC.) Mart.-Lab. D. harra (Forsk.) Boiss. subsp, harra D. h. subsp, confusa Mart.-Lab. D. h. subsp, crassifolia (Rafin) Maire D. h. subsp, lagascana (DC.) O.Bol6s and J.Vigo D. antoniensis Rustan D. glauca (Schmidt) O.E.Schulz D. gorgadensis Rustan subsp, gorgadensis D. g. subsp, brochmanii Rustan D. gracilis (Webb) O.E.Schulz D. hirta (Chev.) Rustan and Borgen D. sundingii Rustan D. varia Rustan D. vogelii (Webb) Cout. D. pitardiana Maire D. acris (Forsk.) Boiss. D. villosa Boul. and Jail. D. griffithii (Hook.f. and Thorns.) Boiss. D. nepalensis Hara Subgen. Rh~nchocarpum (Prantl) Mart.-Lab. Sect. Rhynchocarpum Prantl D. assurgens (Del.) Gren. D. tenuisiliqua Del. subsp, tenuisiliqua D. t. subsp, rupestris (J. Ball.) Mart.-Lab. D. brachycarpa Godr. D. virgata (Cav.) DC. subsp, virgata D. v. subsp, australis Mart.-Lab. D. v. subsp, rivulorum (Br.-B1. and Maire) Mart.-Lab. D. v. subsp, sahariensis (Coss.) Mart.-Lab. D. berthautii Br.-B1. and Maire D. catholica (L.) DC. D. ollivieri Maire D. siifolia G. Kunze. subsp, siifolia D. s. subsp, bipinnatifida (Coss.) Mart.-Lab. D. s. subsp, vicentina (P.Cout.) Mart.-Lab. Sect. Heterocarpum Mart.-Lab. D. D. D. D.

ibicensis (Pau) G6mez-Campo siettiana Maire brevisiliqua (Coss.) Mart.-Lab. ilorcitana (Sennen) Aedo and Mart.-Lab.

Sect. Erucoides Mart.-Lab. D. erucoides (L.) DC. subsp, erucoides D. e. subsp, longisiliqua (Coss.)G6mez-Campo

SINAPIS L.

Sect. Sinapis S. alba L. subsp, alba S. a. subsp, mairei (H.Lindb.) Maire S. a. subsp, dissecta (Lag.) Bonnier S. flexuosa Poir.

Sect. Ceratosinapis DC. S. arvensis L. subsp, arvensis S. a. subsp, allioni (Jacq.) Baillargeon S. a. subsp, nilotica (O.E.Schulz) Baillargeon

Sect. Hebesinapis DC. S. pubescens L. subsp, pubescens S. p. subsp, virgata (Batt.) Baillargeon S. boivinii Baillargeon S. indurata Coss. S. aristidis Coss.

Sect. Chondrosinapis O.E.Schulz S. aucheri (Boiss.) O.E.Schulz ER UCA Mill. E. vesicaria (L.)Cav. subsp, vesicaria E. v. subsp, sativa (Miller) Thell. E. v. subsp, pinnatifida (Desf.) Emb.and Maire COINCYA Rouy C. richeri (Vill.) Greuter and Burdet C. wrightii (O.E.Schulz) Stace C. monensis (L.) Greuter and Burdet subsp, monensis C.m. subsp, cheiranthos (Vill.) Aedo, Leadlay and Mufioz-Garm. C.m. subsp, nevadensis (Willk.) Leadlay C.m. subsp, orophila (Franco) Aedo, Leadlay and Mufioz-Garm. C.m. subsp, puberula (Pau) Leadlay C. transtagana (Cout.) Clem.-Mufioz and Hern.-Bermejo C. longirostra (Boiss.) Greuter and Burdet C. rupestris Porta and Rigo subsp, rupestris C. r. subsp, leptocarpa (Gonz.-Albo) Leadlay RAPHANUS L. R. raphanistrum L. subsp, raphanistrum R. r. subsp, landra (DC.) Bonnier and Layens R. r. subsp, maritimus (Sm.) Thell. R. r. subsp, microcarpus (Lange) Thell.

10 R. r. subsp, rostratus (DC.) Thell. R. sativus L. HIRSCHFELDIA Moench

H. incana (L.) Lagr6ze-Fossat subsp, incana H. i. subsp, incrassata (Thell.) G6mez-Campo SINAPIDENDR ON Lowe

S. angustifolium (DC.) Lowe S. frutescens (Sol.) Lowe subsp.frutescens S. f subsp, succulentum (Lowe) Rustan S. gymnocalyx (Lowe) Rustan S. rupestre Lowe S. sempervivifolium Mnzs. TRACHYSTOMA O.E. Schulz

7". aphanoneurum (Maire and Weiller) M.and W. 7". balli O.E.Schulz T. labasii Maire

The s a m e r e a s o n to avoid u s i n g the s u b s p e c i e s category in B. oleraceaa r e c e n t history in cultivation - s h o u l d be logically applied to B. napus, since this is t h o u g h t to be a n amphidiploid derived from crosses B. oleracea x B. rapa which, m o s t likely, o c c u r r e d in cultivation. However, the s u b s p e c i e s category h a s b e e n traditionally applied to some g r o u p s of B. n a p u s cultivars s u c h as napobrassica, rapifera, pabularia, etc. (not included in Table 1.1). Infraspecific variability of B. rapa (syn. B. campestris) is given a different t r e a t m e n t , p e r h a p s in a c c o r d a n c e with its older history in domestication. For a time, the species category was widely applied (B. chinensis, B. p e k i n e n s i s , B. japonica, etc.) b u t this is now c o n s i d e r e d an excessive license. The s u b s p e c i e s r a n k is only r e c o m m e n d e d for the m o s t significant v a r i a n t s (Oost, 1985) t h o u g h a n intensification of the u s e of n a m e s according to the I n t e r n a t i o n a l Code of N o m e n c l a t u r e for Cultivated Plants (Trehane et al., 1995) would be desirable (Oost, p e r s o n a l c o m m u n i c a t i o n ) . The prioritary n a m e for the species is B. rapa (after the first c o m b i n a t i o n by Metzger in 1833) while the n a m e s u b s p , c a m p e s t r i s s h o u l d be reserved for non specialized semi-wild forms with slender root (Toxopeus et al., 1984). As a m a t t e r of fact, B. c a m p e s t r i s h a s been a very widely u s e d n a m e and, for many, it m i g h t take some effort to a d a p t to the new correct n o m e n c l a t u r e . In the Far East, d o m e s t i c a t i o n led to a wide variety of forms, parallel to those obtained in the M e d i t e r r a n e a n with B. oleracea (except cauliflower!). In the West, the i m p o r t a n c e of B. rapa h a s also been c o n s i d e r a b l e b u t more specialized final

11 forms developed d u e to the "competition" by a n extensive u s e of B. oleracea. The n u m b e r of e p i t h e t s u s e d , either from the E a s t or from the West is very high b u t Oost (1985) s u g g e s t s t h a t only 10-12 s h o u l d merit subspecific rank. Table 1.1 only includes the seven t h a t have been formally c o m b i n e d (Hanelt, 1986), b u t o t h e r epithets as dubiosa, japonica, perviridis, purpurar/a, etc. m i g h t p e r h a p s be equal c a n d i d a t e s for as m a n y s u b s p e c i e s . Upper a c u t e widely e m b r a c i n g leaves a n d long n a r r o w b e a k s in the pods are the best c h a r a c t e r s to d e t e c t B. rapa individuals (B. n a p u s is more g l a b r o u s a n d glaucous, its b e a k is thicker a n d its leaves are only loosely embrasing). An i n t e r n a t i o n a l effort to e s t a b l i s h a c c e p t a b l e criteria in the n o m e n c l a t u r e of Brassica crops s e e m s highly n e c e s s a r y .

B. juncea, a n a m p h i d i p l o i d B. rapa x B. nigra is a n i m p o r t a n t source of edible oil in S. Asia, of vegetables in C h i n a a n d of m u s t a r d c o n d i m e n t elsewhere in the World. Its variation h a s b e e n t h o r o u g h l y s t u d i e d over m a n y y e a r s a n d s o m e s u b s p e c i e s (juncea, crispifolia, foliosa, integrifolia, napiformis; not included in Table 1.1) have often been recognized. Some r e c e n t DNA a n a lyses are of relevance for its taxonomic differentiation (see below). The book by C h o p r a a n d P r a k a s h (1996) is mostly c e n t e r e d on this species a n d is a good source of l i t e r a t u r e references. B. carinata derives by a m p h i d i p l o i d y from one or several B. oleracea x B. nigra c r o s s e s a n d is cultivated locally in E t h i o p i a where it h a s a wide a r r a y of uses" s o u r c e of oils a n d spices, medicinal, vegetable, etc. The valid n a m e for this species is the widely u s e d B. carinata B r a u n a n d not its alternative B. integrifolia (West) Rupr., as it h a s been s o m e t i m e s p r o p o s e d (see Jonsell, 1982, p. 69). IBPGR, now IPGRI (International Plant Genetic R e s o u r c e s Institute) (1987, 1990) h a s p u b l i s h e d d e s c r i p t o r s for B. rapa a n d B. oleracea (+ R a p h a nus) respectively with the aim of helping p r o p e r c h a r a c t e r i z a t i o n of cultivars in this group of species. The six B r a s s i c a species of the U-triangle are u s u a l l y referred to as "crop b r a s s i c a s " , a f o r t u n a t e d e n o m i n a t i o n b e c a u s e B r a s s i c a species outside this g r o u p have a limited a g r i c u l t u r a l i m p o r t a n c e (only B. tournefortii does not belong to the U-triangle a n d is cultivated for oil in India) . However, it s h o u l d be n o t e d t h a t the correct Latin p l u r a l for B r a s s i c a is B r a s s i c a e (not "Brassicas"), so t h a t "brassicas" s h o u l d be only u s e d as a c o m m o n nonL i n n e a n n a m e in o t h e r l a n g u a g e s , w i t h o u t italics or a n initial capital. For f u r t h e r r e a d i n g on this group of species the review by P r a k a s h a n d H i n a t a (1980), is a u s e f u l d a t a source on its biology a n d use. F u r t h e r useful reviews in the s a m e line c a n be found in C h o p r a a n d P r a k a s h (1990, 1996). The infra-specific variability of these cultivated species h a s b e e n the object of diverse molecular, biochemical or morphologically b a s e d a n a l y s e s within the last decade either for B. oleracea (Kresowich et al., 1992; Dias et al., 1992; Dias et al., 1993; Arfls et al., 1987) for B. rapa (Lamboy et al., 1994) or for B. j u n c e a (Jain et al., 1994; B h a t i a et al., 1995).

12

B. o l e r a c e a

wild relatives

B. oleracea, a n Atlantic plant, h a s a n u m b e r of closely related species which grow a r o u n d the M e d i t e r r a n e a n basin. All of t h e m have n = 9 chrom o s o m e s a n d are m o r e or less interfertile a m o n g t h e m s e l v e s a n d with B. oleracea. Knowledge of these h a s been s t i m u l a t e d in the r e c e n t y e a r s as a c o n s e q u e n c e of active IBPGR s u p p o r t e d seed collecting activities (G6mezC a m p o a n d G u s t a f s s o n , 1991) which supplied not only living material b u t also a b u n d a n t geographical a n d ecological data. An i m p o r t a n t review by S n o g e r u p et al. (1990) describes with m u c h detail the t a x o n o m y a n d geograp h y of these taxa. These a u t h o r s propose some n o m e n c l a t u r a l readjustm e n t s , m a i n l y for B. cretica subspecies. The m a x i m u m morphological diversity of the group clearly o c c u r s in Sicily where at least four species - B. macrocarpa, B. villosa, B. rupestris a n d B. incana, from west to e a s t - are present. R a i m o n d o a n d Mazzola (1997), confer the r a n k of s u b s p e c i e s to some other Sicilian t a x a w h i c h are closely related to either B. rupestris or B. villosa (see Table 1.1).

The affinities a m o n g this group of species have been studied from different points of view. S t o r k et al. (1980) describe in detail a n u m b e r of seed c h a r a c t e r s a n d m i c r o - c h a r a c t e r s s u c h as t e s t a layers, surface s t r u c t u r e s a n d mucilage cells t h r o u g h o u t the species complex. G 6 m e z - C a m p o et al. (1999) c o m p a r e a n o t h e r m i c r o - c h a r a c t e r , the morphology of epicuticular wax c o l u m n s , a n d find a distinctive type for B. oleracea, B . a l b o g l a b r a a n d B. bourgaei a n d two o t h e r s for the other wild species. Mithen et al. (1987) analyzed eighteen p o p u l a t i o n s belonging to eleven specific or subspecific taxa for their c o n t e n t s of nine glucosinolates. Some taxonomically meaningful differences were found for wild vs. cultivated B. oleracea, as well as a m o n g wild Sicilian species, a n d also for S a r d i n i a n vs. T u n i s i a n p o p u l a t i o n s of B. insular/s. Aguinagalde et al. (1992) u s e d flavonoids, seed proteins a n d five isozyme s y s t e m s a n d found a comparatively high p h y t o c h e m i c a l diversity in B. cretica, even h i g h e r t h a n for the Sicilian group of species. No differences were found between wild a n d cultivated B. oleracea. In t u r n , B. bourgeaui closely r e s e m b l e s the g r o u p formed by B. oleracea a n d B. m o n t a n a (all lacking isor h a m n e t i n ) , while B. oleracea a n d B. alboglabra, considered co-specific by m o s t a u t h o r s , c a n be d i s t i n g u i s h e d by their flavonoid p a t t e r n s . S t u d i e s with RAPDs a n d isozymes on twenty-two p o p u l a t i o n s belonging to fifteen specific a n d sub-specific t a x a (Ls a n d Aguinagalde, 1998 a,b) clearly d i s t i n g u i s h e s a group with the Sicilian species except B. incana, a second W e s t e r n g r o u p including B. oleracea, B. m o n t a n a a n d also B. incana a n d B. b o u r g e a u i and, finally, a third group including B. alboglabra (suggesting some gene influx) together with B. cretica a n d B. hilarionis. O t h e r importa n t s t u d i e s c o m p a r i n g either species or p o p u l a t i o n s are those by H o s a k a et al. (1990), G u s t a f s s o n a n d L a n n ~ r - H e r r e r a (1997a) a n d Lann~r (1998). Evaluations of interfertility a m o n g all these taxa (Snogerup, 1996) show t h a t r e d u c e d fertility m e a s u r e d by pollen stainability often occurs, b u t is only loosely correlated to morphological differences.

13 Other works focus on single species. Aguinagalde et al. (1991) study eight populations belonging to all the three existing subspecies of B r a s s i c a cretica. By analyzing seed storage proteins and five isoenzyme systems the a u t h o r s find again a high inter-population diversity. The only exception is provided by subsp, taconica (Gustafsson and Snogerup, 1983) whose populations seem to be more homogeneous. Maselli et al. (1996) st udy five enzyme systems on seven populations of B. insularis from Tunisia, Sardinia and Corsica. Though it does not a ppe a r too clearly in their dendrogram, a clinal variation from S o u t h to North is evident if the p a t h followed by the clustering process is closely observed. This agrees with the expectations derived from morphological analyses. A few years before, Widler and Bocquet (1979) had recognized four differentiated varieties of this species in Corsica alone. G u s t a f s s o n a n d Lann~r-Herrera (1997b) compare wild B. oleracea populations u s i n g different criteria while Lann~r-Herrera et al. (1996) perform a similar c o m p a r i s o n on eighteen popul at i ons u s i n g isozyme and RAPDs analyses. Though interesting results were obtained on the intra- and inter-populational variation, no evident correlation with the geographical origin (Spain, France and Great Britain) was found. The truly wild s t a t u s of B. oleracea populations in Noth Spain has been s u p p o r t e d by Fern~ndez-Prieto and Herrera-Gall~stegui (1992) on phytosociological grounds. Regarding B. m o n t a n a , a good detailed a c c o u n t of the French populations with morphological analyses a nd a study of several enzymatic s y s t e m s was produced by Cauwet-Marc et al. (1993). The investigations by Rac a n d Lovric (1991) and by Eastwood (1996) help considerably to u n d e r s t a n d some imperfectly known variability roughly related to B. incana existing in the Adriatic coasts and islands. Trinajsic a nd Dubravec (1986) recognized four different taxa with the range of subspecies, one part ascribed to B. i n c a n a itself and a n o t h e r part to B. botteri, a differentiated form which is recognized to merit specific rank. A critical additional species B. balearica, from Majorca Island, was first considered a small-sized m e m b e r of this group a n d later excluded from it. In fact, it is an d it is not. Snogerup and Persson (1983) studied it cytologically and found t h a t the n = 9 genome is present as part of its 2n = 32 chromosome complement. They suggest t h a t an ancient hybridization involving B. insularis gave rise to this species by amphidiploidy. G6mez-Campo (1993a) suggests t h a t the other p a r e n t might have been a m e m b e r of Subgen. Brassicaria (see below). Seed a nd seedling morphology, the general a p p e a r a n c e of the plant an d some phytogeographical considerations are in favor of this hypothesis a l t h o u g h it is necessary to a c c o u n t for some c h r o m o s o m e losses. In Table 1.1, B. balearica is included in Sect. B r a s s i c a , together with a n o t h e r hybrid species, B. carinata, for which one of the p a r e n t s belongs to the n = 9 genome group. Though B. n a p u s is a similar case, it is placed in Sect. R a p a due to its capacity to form t u b e r o u s roots.

14

The genus Brassica D i s t r i b u t i o n s into sections a n d lists of Brassica species have been proposed in very s e p a r a t e times (Schulz, 1936; Salmeen, 1979) a n d with very different a m p l i t u d e - the former a u t h o r a d m i t s three sections a n d the second nine. These w o r k s have been u s e d as b a c k g r o u n d for the s h o r t analysis which follows. In t u r n , Table 1.1 provides a n u p d a t e d version where m o s t r e c e n t r e s e a r c h r e s u l t s have been incorporated. U-triangle species a n d their r e l a t i v e s - here all included in Subgen. Brassica - s h a r e a few c o m m o n c h a r a c t e r s s u c h as the p r e s e n c e of seeds in their pod b e a k s (or at least the potentiality for it), spherical or quasi spherical seeds, n o t c h e d cotyledons a n d well defined l y r a t e - p i n n a t i p a r t i t e b a s a l a n d m e d i a n leaves, where s i n u s e s r e a c h the mid-nerve at least toward the leaf base. D o u b t s in the i n t e r p r e t a t i o n s o m e t i m e s arise b e c a u s e some of the above c h a r a c t e r s m a y a p p e a r in a regressive form a n d b e c o m e difficult to detect. For i n s t a n c e , a p a t i e n t observation of m a n y pods of B. oleracea m a y be n e e d e d to find only a few seeded beaks. It m a y be even more difficult with the slender long b e a k s of B. rapa, t h o u g h at least some seed primordia can be discovered w h e n green pods are observed. In B. nigra, the p r o n o u n c e d s h o r t e n i n g of the whole fruit m i g h t r e n d e r the s a m e t a s k impossible. However, all o t h e r c h a r a c t e r s agree with those of the group. In o t h e r taxa, leaves m i g h t show a r e d u c t i o n in the n u m b e r of their s e c o n d a r y s e g m e n t s so t h a t w h e n these are a b s e n t (as in B. carinata) the r e s u l t a n t simple silhouette can h a r d l y be a s s o c i a t e d with a lyrate leaf. Five sections have been recognized in Subgen. Brassica (Table 1.1). Sect Brassica h a s a l r e a d y been d i s c u s s e d above. While S a l m e e n (1979) considers t h a t B. rapa alone deserves a Sect. Rapa, the a m p h i d i p l o i d s B. napus a n d B. juncea, have b e e n a d d e d to this, since all three have the capacity to form t u b e r o u s roots even if this c h a r a c t e r is not always expressed. However, it is recognized t h a t Sect. Rapa a n d Sect. Brassica are akin. The B. f r u t i c u l o s a / s p i n e s c e n s / maurorum complex, all with n = 8, together with B. procumbens from Algeria a n d B. cadmea clearly s h a r e the s a m e c h a r a c t e r s mentioned above for b e a k s , seeds, cotyledons a n d leaves. They m i g h t r e p r e s e n t the closest relatives of B. nigra (Truco a n d Quir6s, 1995) a n d they are all p u t together in Sect. Micropodium. B. dej~exa deserves a special section b a s e d on its deflexed siliques, some cytological c o n s i d e r a t i o n s (unique Brassica species with n = 7) a n d a n i n d u m e n t u m with very long p a t e n t h a i r s which is s o m e h o w atypical. B. assyriaca is c o n s i d e r e d to fall within the variability of B. dej~exa. The trio B. tournefortii / B. barrelieri / B. oxyrrhina also shows spherical seeds, seeded b e a k a n d lyrate leaves, a l t h o u g h b e c a u s e of their t e n d e n c y to form c o m p a c t basal rosettes the leaves of B. barrelieri a n d B. oxyrrhina are b e t t e r described as r u n c i n a t e . In Table 1.1 they have been conservatively g r o u p e d together u n d e r Sect. Sinapistrum a l t h o u g h some recent r e s e a r c h s u g g e s t s t h a t the trio is not h o m o g e n e o u s (Horn a n d V a u g h a n , 1983; P r a d h a n et al. 1992). Their similitudes a n d differences can be well d e s c r i b e d by c o n s i d e r i n g all possible pairs of species v e r s u s the r e m a i n i n g

15 third species. T h u s , B. barrelieri a n d B. oxyrrhina are identical in the vegetative stage by their a d p r e s s e d r o s e t t e s a n d can be well d i s t i n g u i s h e d from B. tournefortii. B. tournefortii a n d B. oxyrrhina s h a r e small sized flowers probably a s s o c i a t e d with a u t o g a m y while B. barrelieri flowers are bigger. In t u r n , B. barrelieri a n d B. tournefortii b e a k s are s h o r t e r t h a n t h o s e of B. oxyrrhina. The last species is also u n i q u e in s h o w i n g white (against yellow) flowers. Let u s finally a d d a n o n - t a x o n o m i c a l fact: B. tournefortii is often cultivated in India as a s o u r c e of oil while the two o t h e r s are only wild. A n o t h e r quite different g r o u p - Subgen. Brassicaria -exemplified by B. repanda (n = 10) always s h o w s a seedless beak, their seeds are flattened to a greater or lesser extent, a n d their leaves c a n rarely be described as properly lyrate b u t r a t h e r as s i n u a t e or pinnatifid (sinuses never or very rarely reach the mid-nerve). Their t e n d e n c y to be s c a p o s e a n d / o r to show s h o r t s u b t e r r a n e a n s t e m s with leaf s c a r s (as if they were small b u r i e d b u s h e s ) is also characteristic. B. repanda h a s a l m o s t fifteen, often poorly defined, s u b s p e c i e s from the M a r o c c a n Atlas to the E u r o p e a n Alps. Galland (1988) found highly polyploid forms in the Great Atlas, a u n i q u e case for the g e n u s Brassica. B. glabrescens from N. Italy s h o u l d be c o n s i d e r e d as an additional s u b s p e c i e s of B. repanda. Significantly, B. repanda is a b s e n t from the Balearic Islands. F u r t h e r to the E a s t in Europe, B. jordanoffii a n d B. nivalis s h a r e the s a m e set of c h a r a c t e r s a n d are very local in Bulgaria a n d Greece, respectively. Akeroyd a n d Leadlay (1991) s u g g e s t e d t h a t b o t h s h o u l d be only s e p a r a t e d at the subspecific level, b u t they s h o w sufficient morphological differences a n d different c h r o m o s o m e n u m b e r s (n = 11 a n d n= 10, respectively). In t u r n , B. elongata is very c o m m o n from the B a l k a n s to I r a n a n d it occasionally o c c u r s to the West (Roux a n d G u e n d e , 1995). In fact, two s u b s p e cies are local in Morocco. It is not always completely s c a p o s e a n d c o n t a i n s an n = 11 genome. In North Africa, there are other m e m b e r s of the group s u c h as B. gravinae, B. setulosa and B. loncholoma from Algeria a n d B. desnottesii local in Morocco, the last three close to B. repanda. Also, the original description of B. somaliensis strongly a d v o c a t e s for it to be included in Subgen. Brassicaria. Most r e c e n t r e s u l t s t e n d to confirm t h a t m e m b e r s of Subgen. Brassicarla are very s e p a r a t e from Subgen. Brassica. For i n s t a n c e , Clemente-Mufioz a n d H e r n ~ n d e z - B e r m e j o (1980) o b t a i n seven d e n d r o g r a m g r o u p i n g s in Brassica, in w h i c h all s e e d l e s s - b e a k e d species fall into the s a m e group, separate from all o t h e r m e m b e r s of the genus. Curiously, they did not s t u d y fruits at all b u t only the m o r p h o l o g y of the sterile p a r t s of the flower, sepals, petals, nectaries, which is considered to be very c o n s t a n t t h r o u g h o u t the whole Brassicaceae family. F u r t h e r s u p p o r t for the s a m e idea can be found in m a n y r e c e n t morphologically or biochemically b a s e d w o r k s ( T a k a h a t a a n d Hinata, 1986; Horn a n d V a u g h a n , 1983, etc.). However, some of these d a t a seem to s u g g e s t a s e p a r a t e section for B. elongata.

16

B. souliei from NW Africa a n d Sicily a n d B. dimorpha from Algeria do not easily fit in a n y of the above sections. Both are morphologically closer to Subgen. Brassicaria b u t they c o n s t a n t l y a p p e a r very s e p a r a t e from other Brassica t a x a in m o s t recently p r o d u c e d m o l e c u l a r - b a s e d d e n d r o g r a m s . Two d e c a d e s ago, S a l m e e n (1979) placed t h e m in Sect. Nasturtiops which is here recognized a n d located within Subgen. Brassicaria.

Other related genera Erucastrum a n d Diplotaxis have traditionally b e e n considered as very close relatives of Brassica, a n d several r e c e n t investigations s t u d y the relative positions of the t h r e e genera. S~nchez-Y~lamo (1990) a n d S~nchez-Y~lamo et al. (1992) s u c c e s s f u l l y differentiate t h e m on the b a s i s of seed proteins. S~nchez-Y~lamo a n d Aguinagalde (1996) i n c o r p o r a t e d s t u d i e s with flavonoids. M a n y o t h e r c o m p a r i s o n s a m o n g these three g e n e r a have been carried out within s t u d i e s on larger g r o u p s of t a x a (below). Some specific a s p e c t s of the t a x o n o m y of Erucastrum have been studied by G 6 m e z - C a m p o (1982, 1983, 1984). F o r m e r t a x a k n o w n u n d e r E. laevigaturn are d i s t r i b u t e d b e t w e e n E. littoreum a n d E. virgatum. A new species, E. ifniense, is newly d e s c r i b e d as a c o n t i n e n t a l v i c a r i a n t of the M a c a r o n e s i a n group (E. canariense a n d E. cardaminoides). A n o t h e r controversial taxon from Morocco formerly k n o w n u n d e r several generic d e n o m i n a t i o n s is t r a n s ferred into this g e n u s as E. rifanum. Hirschfeldia incana a n d Erucastrum littoreum are p r o p o s e d as p a r e n t s of the amphidiploid species E. elatum, a hypothesis later confirmed by S~nchez-Y~lamo (1992) b a s e d on isoenzyme a n a lysis. The recognition of sections within Erucastrum r e m a i n s an open possibility. If we restrict ourselves to the c i r c u m - m e d i t e r r a n e a n taxa, E. gallicum, E. leucanthum a n d E. nasturtiifolium show c h a r a c t e r s closer to Diplotaxis (thinner pods, smaller s e e d s a n d shallowly n o t c h e d cotyledons) while E. virgatum, E. littoreum or E. varium are s o m e h o w closer to Brassica. The species of E a s t a n d S o u t h Africa are a p p a r e n t l y closer molecularly to the Diplotaxislike trio so t h a t f u r t h e r detailed morphological or caryological c o m p a r i s o n s between the species of each biogeographic a r e a would be convenient to clarify the possibility of e s t a b l i s h i n g sections. J o n s e l l (1982) h a s described two new species, E. elgonense in U g a n d a a n d E. m e r u e n s e in Tanzania.

Hirschfeldia is very similar to Erucastrum b u t its a m p l i t u d e as a g e n u s h a s been differently interpreted. The r e a s o n lies in its definition by a combin a t i o n of c h a r a c t e r s w h i c h are often feeble a n d do n o t always occur together even in the type species H. incana. In o u r opinion, H. incana should p e r h a p s r e m a i n as s u c h b u t H. rostrata from S o k o t r a Island s h o u l d be ascribed to Erucastrum. H. incana s u b s p , incrassata is in m a n y r e s p e c t s intermediate between Hirschfeldia a n d Erucastrum. Diplotaxis h a s a t t r a c t e d m u c h interest, as j u d g e d by the n u m b e r of papers p r o d u c e d . G 6 m e z - C a m p o (1981a) gives specific s t a t u s to D. ibicensis

17 a n d ascribes a frequently confused yellow f o w e r e d taxon from Algeria to D. erucoides- as s u b s p , longisiliqua. The work by Martinez-Laborde (1988ab, 1989, 1991a, 1991b, 1991c, 1992 a n d 1993) is i m p o r t a n t b e c a u s e it not only brings to light a n d gives a proper specific s t a t u s to some o b s c u r e taxa s u c h as D. ilorcitana, D. brevisiliqua, D. brachycarpa, etc. a n d p r o p o s e s several infraspecific taxa within some variable species s u c h as D.virgata, D. harra and D.siifotia, b u t also p r e s e n t s an u p d a t e d s y s t e m for the genus. This system is f u r t h e r developed by the s a m e a u t h o r within a recent p a p e r by G6m e z - C a m p o a n d Martinez-Laborde (1998) a n d is fully reflected in Table 1.1. In turn, B r o c h m a n n et al., (1997) exhaustively refer to the frequently neglected taxa of Cape Verde Islands (also included in Table 1.1). S~nchezY~lamo (1994) s t u d i e s flavonoid c o n t e n t of m a n y Diplotaxis species w i t h o u t clearly d i s c r i m i n a t i n g the s u b g e n e r a , while the work by S~nchez-Y~lamo a n d Martinez-Laborde (1991) on the isozymes of Subgen. Diplotaxis s h e d s light on the p a r e n t s of the amphidiploid species D. muralis. S o b r i n o - V e s p e r i n a s (1985, 1993, 1996) refers to some p u n c t u a l p r o b l e m s of this genus. In the work by Warwick et al. (1992) based on chloroplast DNA, a lack of congruity between m o l e c u l a r a n d morphological d a t a is reported. However, it is noteworthy (Table 1.1) that, at least within the s u b g e n e r a a n d sections of Diplotaxis, there is a high degree of congruity between morphological a n d molecular results. In Diplotaxis, leaves are always pinnatifid or p i n n a t i s e c t (sinuses never reach the mid-nerve) a n d seeds are always small a n d more or less ovoid or elliptic. Two of the s u b g e n e r a (Diplotaxis a n d Hesperidium) c o n s t a n t l y include species with seedless beak. Together with Brassica, Diplotaxis is u n i q u e in containing b o t h k i n d s of taxa - with seedless a n d seeded beaks. It is to be noted t h a t the presence of seeded b e a k s (hetero-arthrocarpic fruits) is an exclusive d e v e l o p m e n t of the tribe Brassiceae, p r e s e n t only in p a r t of the genera. It is believed t h a t m u c h of the general variability p r e s e n t in Brassica a n d Diplotaxis including molecular heterogeneity is, in fact, a s s o c i a t e d to this b e a k duality. Exclusively b a s e d on floral m e a s u r e m e n t s , Hern~ndezBermejo a n d Clemente (1986) found a m a x i m u m variability in Brassica, followed by Diplotaxis a n d t h e n by Erucastrum, well above t h a t of sixteen other related genera. The s a m e three genera p r e s e n t the h i g h e s t variability at the molecular level (Warwick a n d Black, 1991, 1993). However, Erucastrum does not show a n y convincing signs of b e a k duality.

Raphanus is treated in an extensive morphological study, by Pistrick (1987). Two species are recognized viz. Raphanus sativus a n d R. raphanistrum, the latter including several subspecies. The origin a n d the infraspecific variability of Raphanus sativus h a s merited special a t t e n t i o n a n d a m o n g s t the m o s t recent p a p e r s on this species, those by Crisp (1995) a n d Rabbani et al. (1998) s h o u l d be m e n t i o n e d . The i n d e h i s c e n t fruit of Raphanus is i n t e r p r e t e d as a fully developed b e a k i.e. w i t h o u t valvar portion. However, at least in R. raphanistrum, a stereomicroscope can often help to

18

detect two small scales at the base of the fruit vestigially representing the missing valves.

Sinapis is the object of a detailed thesis by Baillargeon (1986). This author distinguishes four sections (Table 1.1) and introduces some interesting novelties s u c h as placing all cultivated forms of S. alba u n d e r subsp, alba and all wild ones u n d e r subsp, mairei. He also describes or recombines some other taxa by s u b o r d i n a t i n g them u n d e r S. arvensis or S. pubescens (Baillargeon, 1983). The morphological and molecular heterogeneity present in genus Sinapis can easily be correlated with the existence of two basic chromosome n u m b e r s , n = 9 and n = 12. All the species are hetero-arthrocarpic. Coincya h a s been studied in a n o t h e r thesis (see Leadlay and Heywood, 1990) soon after u p d a t e d for Spanish material by Leadlay (1993). Both works constitute a significant step toward u n d e r s t a n d i n g this difficult heteroarthrocarpic genus. The t r e a t m e n t is synthetic and gets rid of a n u m b e r of superfluous n a m e s t h a t had produced m u c h confusion, mostly in the Iberian P en in s u la where the genus reaches its m a x i m u m variability. SobrinoVesperinas (1991) carried out hybridizations with material from Sierra Morena (S.C. Spain) to s t u d y the inheritance of fruit shape. An extensive phytochemical s t u d y of the lipids by Vioque-Pefia (1992) h a s no significant systematic implications. Molecular studies (Warwick and Black, 1993) show a distinct and f u n d a m e n t a l l y hom oge ne ous genus. Trachystoma, with three species, has been the object of some intergeneric crosses (see c h a p t e r s 3 and 4 of this book) and also of anatomic studies on its strongly hetero-arthrocarpic fruit (Giberti, 1984). It is known (Maire and S a m u e l s s o n , 1937) to hybridize s p o n t a n e o u s l y with Ceratocnemum. In a way, this challenges the presently defined limits for the ~coenospecies" and invites an exploration of several other genera with shortened fruits. Eruca h a s become a monotypic genus after two poorly known former Eruca species (setulosa and loncholoma) from North Africa are ascribed to Brassica Subgen. Brassicaria (Table 1.1). The uni que species E. vesicaria is an a n n u a l n o n -he t e r o- a r t hr oc a r pi c plant, one of whose subspecies (subsp. sativa) h as reached c i r c u m - m e d i t e r r a n e a n distribution and is cultivated in m a n y other parts of the World. The difficulty to distinguish the three (or perh a p s four) subspecies of E. vesicaria using pressed material has been noted by G6mez-Campo (1993b), but it is expected t hat further characterization work would clarify this. Sobrino-Vesperinas (1995) observed partial sterility between subsp, sativa and subsp, vesicaria. Sinapidendron is a n o t h e r apparently seedless-beaked genus with five species plus one subspecies restricted to Madeira Island (Hansen and Sunding, 1993). Former S. palmense should be referred to Sinapis pubescens (Rustan, 1980). Sinapidendron is woody and the only non-heteroarthrocarpic genus which belongs to the so called ~nigra" molecular lineage (see next ch ap te r or Warwick and Black 1991; for B. nigra itself see above). Testing an obvious possible interpretation, the a u t h o r of this chapter stu-

19 died several h u n d r e d b e a k s in s e a r c h for vestigial seed primordia, so far w i t h o u t success.

The tribe Brassiceae Table 1.2 tries to u p d a t e previous lists with all the g e n e r a of the tribe Brassiceae t o g e t h e r with their e s t i m a t e d n u m b e r of species a n d the type of fruit exhibited. S u b g e n e r a for Brassica a n d Diplotaxis are also included. Novelties c o n s i s t of Quidproquo a n d Dolichorhynchus, while Reboudia is det a c h e d after its u n i q u e species was placed u n d e r Erucaria by G r e u t e r et al. (1986). We have only tentatively re-included Calepina, very distinct, b u t of doubtful position elsewhere in the family Brassicaceae. It is obvious t h a t not all these 54 g e n e r a (with r o u g h l y 240 species) have received the s a m e attention in the p a s t two decades. Only those not t r e a t e d above b u t considered in recent s t u d i e s will be briefly c o m m e n t e d , s o m e t i m e s with still briefer references to s o m e of their m o s t relevant relatives.

Moricandia is often considered to belong to the Brassica coenospecies on the basis of morphological a n d cytogenetical similarities. The g e n u s pres e n t s its m a x i m u m variability in N. Africa (where M. suffruticosa, M. spinosa, M. foleyii a n d M. nitens are endemic) a n d in the Iberian P e n i n s u l a (where M. moricandioides a n d M. foetida are endemic). S o b r i n o - V e s p e r i n a s (1983) suggests t h a t so called M. arvensis var. robusta Batt. from the C o n s t a n t i n e a r e a in Algeria is exactly the s a m e form which once e s c a p e d a n d h a s now invaded the M e d i t e r r a n e a n b a s i n as a weed. The s a m e a u t h o r p o s t u l a t e s the identity of M. sinaica (W. Asia) with M. arvensis var. g a r a m a n t u m Maire from the Hoggar m a s s i f (S. Algeria). The m o s t e a s t e r n m e m b e r of the tribe Brassiceae, Douepia is very similar to Moricandia except for its capitate stigma a n d its s a b a n a - o r i e n t e d fenology. A m m o s p e r m a a n d Pseuderucaria are a d a p t e d to s a n d y s u b d e s e r t i c h a b i t a t s a n d are very similar to each other. Quezeliantha was described u n d e r Quezelia by Scholz (1966) b u t the original generic n a m e was later a d j u s t e d (1982) by the s a m e a u t h o r . This grows in Tibesti massif. Vella w a s revised by G 6 m e z - C a m p o (198 lb). Crespo (1992) describes a new distinct species V. lucentina in SE Spain, not far from Alicante. More recently, Crespo et al. (1999) have p r o d u c e d a c o m b i n e d a n a l y s i s of the subtribe Vetlinae involving ITS ribosomal s e q u e n c e s a n d morphological data. In t u r n , Ponce-Diaz (1998) h a s s t u d i e d the s a m e g r o u p with i s o e n z y m e s a n d ISSR m a r k e r s . Warwick a n d A1-Shehbaz (1998) propose to include Boleum a n d Euzomodendron within Vella. However, the three g e n e r a exhibit very distinct sets of adaptive c h a r a c t e r s in a c c o r d a n c e with their respective mec h a n i s m s for seed dispersal. Quidproquo is a new g e n u s p r o p o s e d by G r e u t e r a n d B u r d e t (1983) for material from L e b a n o n a n d Israel t h a t h a d been e r r o n e o u s l y included in Sinapis aucheri. A s t u d y by Baillargeon (1985) h a s d i s s i p a t e d some previous d o u b t s on its t a x o n o m i c s t a t u s a n d geographical distribution. Its fruit s h o w s

20 a well developed seeded beak. Dolichorhynchus was described by Hedge and Kit (1987) from W e s t e r n Arabia. It is a desert a d a p t e d p l a n t resembling Moricandia b u t exhibiting seeded beaks.

Crambe h a s often a t t r a c t e d the a t t e n t i o n of b o t a n i s t s b e c a u s e of its evolved simplified fruits ( n u c a m e n t a c e o u s , derived from one-seeded beaks) a n d the a n t i q u i t y s u g g e s t e d by the E-W geographic d i s j u n c t i o n it presents. Using flavonoids, Aguinagalde a n d G 6 m e z - C a m p o (1984) reflect s u c h disj u n c t i o n at the biochemical level. Khalilov (1991) r e a d j u s t s the sections of this g e n u s after i n c l u d i n g two new species. More recently Warwick a n d Black (1997) s t u d y c h l o r o p l a s t DNA a n d F r a n c i s c o - O r t e g a et al. (1999) ribosomal ITS s e q u e n c e s with similar results. Crambe s e e m s to be a well defined g e n u s with clearcut limits a n d no evident close relatives. Division of the tribe Brassiceae into s u b t r i b e s h a s been an unresolved issue for a long time (Schulz, 1919; J a n c h e n , 1942) mainly b e c a u s e it is difficult to e s t a b l i s h a d e q u a t e criteria. Today, m o l e c u l a r m e t h o d s can be very useful at providing a rich source of h y p o t h e s e s (Yanagino et al. 1987; Song et al., 1990; Warwick a n d Black, 1991, 1994, 1997). Clustering m e t h o d s a r o u n d r e p r e s e n t a t i v e genera might be the way to define indubitable n a t u r a l groups, b u t as morphological, biochemical or m o l e c u l a r phenetic distances become greater, the b o u n d a r i e s of these defined g r o u p s become more and more diffuse. The case of the Vellinae is a good example of this situation (Warwick a n d Black, 1994; Crespo et al., 1999 a n d Ponce-Diaz, 1998). It s e e m s obvious t h a t Boleum, Euzornodendron a n d Carrichtera are the closest allies to Vella, followed by Succowia a n d Psichyne in this order. On the contrary, Schouwia, s h o w i n g a winged fruit similar to t h a t of Psichyne, is normally rejected as a relative of this group. All these genera show seedless b e a k a n d u s u a l l y s h o r t e n e d fruits a n d perennial habit, being a d a p t e d to either semiarid or m e s o p h y t i c s t e p p e s or m o u n t a i n s . Thus, the subtribe Vellinae s e e m s to c o r r e s p o n d to a n a t u r a l a n d c o h e r e n t group where Euzomodendron might r e p r e s e n t the long-fruited a r c h e t y p e a n d Succowia an evolved a n n u a l representative. It is u n f o r t u n a t e t h a t Kremeriella was not t a k e n into a c c o u n t b e c a u s e its a s y m m e t r i c u n i l o c u l a r fruit might well have derived from a bilocular one by lateral abortion. A fusion of s u b t r i b e s VeUinae a n d Savignynae was proposed by the a u t h o r of this article on the basis of their seed wing (sometimes vestigial) b u t molecular d a t a (Ponce-Diaz, 1998) suggest t h a t they s h o u l d be kept separate. Henophyton (perennial) a n d Savignya (annual), are not too d i s t a n t from each o t h e r a n d are b o t h a d a p t e d to more arid e n v i r o n m e n t s in North Africa. Quezeliantha, from Tibesti, might be also ascribed to the subtribe Savignynae. Therefore, this subtribe is small a n d its limits are not well defined. The s a m e o c c u r s with Cakilinae, where the s u p p r e s s i o n of Reboudia h a s left the pair Erucaria a n d Cakile alone. The isolated position of Crambe a n d its evolved strongly hetero-arthrocarpic fruit m i g h t well deserve a monotypic s u b t r i b e (Crambinae). The E-W

21 T a b l e 1.2 Genera and subgenera of the tribe Brassiceae (Cruciferae).

+ H H H H H H H H + H

H H H H H ?

Ammosperma (1) Boleum (1) Brassica Subgen. Brassica (27) Subgen. Brassicaria (11) Cakile (7) Calepina (1) Carrichtera (1) Ceratocnemum (1) Chalcanthus (1) Coincya (6) Conringia (6) Cordylocarpus (1) Crambe (35) Crambella (1) Didesmus (2) Diplotaxis Subgen. Diplotaxis (4) Subgen. Hesperidium (14) Subgen. Rhynchocarpum (13) Dolichorrhynchus (1) Douepia (1) Enarthrocarpus (5) Eremophyton (1) Eruca (1) Erucaria (6) Erucastrum (21) Euzomodendron (1) Fezia (1) Foleyola (1)

In parentheses: estimated number of species. H = heteroarthrocarpic genera or subgenera. + = genera with species of both types. ? = fruit status doubtful.

H H H H ? H H H H

H H H H

H H

?

Fortuynia (2) Guiraoa (1) Hemicrambe (1) Henophyton (2) Hirschfeldia (1) Kremeriella (1) Moricandia (7) Morisia (1) Muricaria (1) Orychophragmus (1) Otocarpus (1) Physorrhynchus (2) Pseuderucaria (3) Pseudofortuynia (1) Psychine (1) Quezeliantha (1) Quidproquo (1) Raffenaldia (2) Raphanus (2) Rapistrum (2) Rytidocarpus (1) Savignya (2) Schouwia (2) Sinapidendron (5) Sinapis (8) Succowia (1) Trachystoma (3) Vella (5) Zilla (2)

22 M e d i t e r r a n e a n geographic d i s j u n c t i o n it p r e s e n t s is i n t e r p r e t e d as an indication of antiquity. At first view, Crambella or Muricaria fruits are similar to those of Crambe b u t m o l e c u l a r r e s u l t s (Warwick a n d Black, 1997; FranciscoO r t e g a et al., 1999) do not s u p p o r t the existence of a close relationship. A similar s i t u a t i o n o c c u r s with Hemicrambe. F u r t h e r s t u d i e s are n e c e s s a r y to find a suitable position for t h e s e genera. Also, m a n y a u t h o r s have found similitude between Crambe a n d Calepina b a s e d on their n u c a m e n t a c e o u s fruits. In o u r opinion, the u n i q u e p e n d e n t seed found in Calepina fruit m e a n s t h a t a d r a m a t i c r e d u c t i o n a n d loss of d e h i s c e n c e of the valvar portion h a s t a k e n place while the u n i q u e erect seed of Crambe fruit m e a n s t h a t we are faced with a r o u n d e d o n e - s e e d e d beak. In o t h e r words, it is a case of mere convergence w h e r e the fruit of Calepina is derived from the valves a n d t h a t of Crambe from the beak. On the other h a n d , it is d o u b t f u l t h a t Calepina a m e m b e r of the tribe Brassiceae. Were it ever fully a c c e p t e d in the tribe, it would merit a n o t h e r monotypic s u b t r i b e for itself. All m e m b e r s of the s u b t r i b e ZiUinae (Zilla, Foleyola, Physorrhynchus a n d Fortuynia) s h a r e c o m m o n d e s e r t - a d a p t i v e morphological traits (Schulz, 1936) a n d are a p p a r e n t l y close molecularly (Warwick a n d Black, 1994, Crespo, pers. comm.}. F r u i t s in the E a s t e r n g e n e r a (Physorrhynchus a n d Fortuynia) are clearly h e t e r o - a r t h r o c a r p i c . However, seeds in the w e s t e r n genera (Zilla, Foleyola) are p e n d e n t , strongly s u g g e s t i n g t h a t their simplified fruits might not c o r r e s p o n d to b e a k s b u t to i n d e h i s c e n t valvar portions. If this is confirmed t h r o u g h a n a t o m i c a l studies, the s t r u c t u r e of this s u b t r i b e s h o u l d p e r h a p s be t h o r o u g h l y reconsidered. For the r e m a i n i n g s u b t r i b e s Brassicinae, Raphaninae a n d Moricandinae, it is p r e m a t u r e to try to modify the p r e s e n t s t a r e s b e c a u s e their limits are u n d e r c o n s t a n t a s s a u l t by the r e s u l t s of new r e s e a r c h a n d interpretations. B e a k d e v e l o p m e n t in size or s h a p e a n d / o r fruit s h o r t e n i n g are agile evolutionary t r e n d s w h o s e variation c a n often be observed within a single g e n u s (for i n s t a n c e Coincya, Trachystoma, etc.) while n a t u r a l h y b r i d s are frequently found between long fruited g e n e r a - T r a c h y s t o m a a n d Cordylocarpus- a n d s h o r t fruited ones s u c h as Ceratocnemum a n d Rapistrum respectively. Thus, s u b - t r i b e Raphaninae h a s p r o b a b l y derived polyphyletically from different m e m b e r s of the s u b t r i b e Brassicinae a n d a c l e a r - c u t limit between both cannot really be e s t a b l i s h e d . The Moricandinae are also close to the Brassicinae in m a n y respects, their differences being mostly a s s o c i a t e d with a d a p t a t i o n of the former to more xerophytic h a b i t a t s . We s h o u l d note t h a t while subtribe Moricandinae only c o n t a i n s n o n - h e t e r o - a r t h r o c a r p i c g e n e r a (with seedless beaks) a n d s u b t r i b e Raphaninae only c o n t a i n s h e t e r o - a r t h r o c a r p i c gen e r a (with seeded beaks), s u b t r i b e Brassicinae c o n t a i n s both types of genera. F u r t h e r m o r e , both t r e n d s are p r e s e n t within Diplotaxis a n d Brassica. If this m o r p h o g e n e t i c c h a r a c t e r is eventually recognized a higher relative taxonomic i m p o r t a n c e with r e g a r d to other merely adaptive c h a r a c t e r s (see next chapter) this would m e a n a split not only for s u b t r i b e Brassicinae, b u t also for the g e n e r a Diplotaxis a n d Brassica. If this idea is t a k e n further, this could

23 lead to the recognition of only two subtribes (genera with seedless beak and genera with seeded beak) but this seems somewhat exaggerated. However, giving an excessive or u n b a l a n c e d emphasis to molecular data might equally lead to similar exaggerated situations. Future developments should be based on the intelligent integration of the new information which is continuously arriving from different directions.

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