Rubiaceae) in the Bulgarian Flora
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PHYTOLOGIA BALCANICA 17 (3): 291 – 314, Sofia, 2011 291 Galium sect. Leiogalium (Rubiaceae) in the Bulgarian flora Minčo Ančev1 & Franz Krendl2 1 Department of Plant and Fungal Diversity and Resources, Institute of Biodiversity and Ecosystem Resarch, Bulgarian Academy of Sciences, Acad. Georgi Bonchev St., bl. 23, 1113 Sofia, Bulgaria, e-mail: [email protected] 2 Botanische Abteilung, Naturhistorisches Museum Wien, Burgring 7, A 1010 Wien, Austria Received: June 06, 2011 Accepted: November 17, 2011 Abstract. The work contains the results from the investigation of morphological variation, chromosome numbers and ploidy levels, distribution, phytogeographic and phylogenetic relationships of the species of genus Galium sect. Leiogalium, occuring on the territory of Bulgaria. The section includes 18 species and two non-nominal subspecies. Morphologically, phytogeographically and supposedly phylogenetically related species are divided into five species groups. The species are cross-pollinated entomophilous plants, which reproduce sexually and vegetatively by underground runners.The mesophilous species with white flowers, G. album, G. intermedium, G. lucidum, G. pashale, and G. procurrens, are pollinated chiefly by flies of Syrphidae, Muscidae and Larvivoridae. The xerophilous G. aegeum, G. mirum, G. asparagifolium, G. flavescens, G. rhodopeum with pale yellowish to greenish corolla are visited mostly by small coleopterans of the genera Strangalia, Agriotes, Mordelis, etc. Six species are Balkan endemics: G. mirum, G. macedonicum, G. rigidifolium, G. rhodopeum, G. aegeum and G. procurrens. Galium velenovskyi is a local endemic, restricted in its occurence to the calcareous slopes of E Rhodopi Mts. The chromosome numbers and the ploidy levels of 18 species and two subspecies studied in 95 populations are reported in the article. Eight species are diploid, nine are tetraploid, and one is hexaploid, all with x = 11, the most common and probably original basic chromosome number in the genus. G. ×pomeranicum (G. album × G. verum) is polyploid with 2n = 44. Key words: Bulgaria, chromosome numbers, endemics, flora, Galium, hybridization, Leiogalium, phylogenetic relationships, polyploidy, reproductive biology Introduction the taxonomic studies of Galium. This resulted in taxo- nomic revisions published in a few papers (Ančev 1971, Genus Galium in the Bulgarian botanical literature 1975, 1978; Anchev 1982; Ehrendorfer 1975) and subse- was treated with different taxonomic content. Velenovs- quently included in Flora RP Bulgaricae (Ančev 1989). ký (1891, 1898) reported 26 species in his Flora Bulgari The accepted taxonomic structure followed Flora Eu ca and Supplementum I to it. Stojanov & Stefanov (1925) ropaea (Ehrendorfer & al. 1976), with morphologically included 21 species and six non-nominal subspecies in well differentiated species and species groups, which in- the first edition of the Flora of Bulgaria. That taxonom- cluded closely related taxa. ic structure remained almost unchanged in the follow- Galium is now represented in the Bulgarian flora by ing three editions of the Flora of Bulgaria (Stojanov & 38 species, four nothospecies, two non-nominal subspe- Stefanov 1933, 1948; Stojanov & al. 1967). In the next cies, six varieties, and seven forms. Thirty-one species twenty years, the progress of cytotaxonomic investiga- are perennial plants, and seven are annuals, all classi- tions in systematic botany in Bulgaria had influenced fied into six sections: Platigalium Koch (3 spp.), Apari 292 Ančev, M. & Krendl, F. • Galium sect. Leiogalium in Bulgaria noides (Jord.) Gren. (3 spp.), Hylaea (Griseb.) Ehrend. Systematic treatment (1 sp.), Trachygalium K. Schum. (1 sp.), Galium (3 spp.), Leiogalium Ledeb. (18 spp.), Leptogalium Lange (2 spp.), Conspectus of Galium sect. Leiogalium species Aparine Lange (6 spp.), and Pseudovalantia Lange (1 sp.) and subspecies in the Bulgarian flora (Ančev 1978, 1989). Sect. Leiogalium, which comprises (with reference to the ploidy levels based on some 50 % of all Bulgarian species in it, is the largest and chromosome counts in Bulgarian populations, in taxonomically most complicated one. square brackets; see also Appendix 2) In the present communication on sect. Leiogalium, we have summarized the accumulated knowledge on Sect. Leiogalium Ledeb. its species diversity in the Bulgarian flora, its distri- 1–2. G. mollugo group bution and ecology, geographical relations, chromo- 1. G. lovcense Urum. (incl. G. protopycnotrichum some numbers and ploidy levels, the polyploidy and Ehrend. & Krendl) [2x] its correlation with the root system (taproot or root- 2. G. album Mill. [4x] stock with underground runners). The role of hybrid- subsp. album ization and polyploidy is discussed for the variation subsp. pycnotrichum (Heinr. Braun) Krendl and speciation in the genus. subsp. prusense (K. Koch) Ehrend. & Krendl 3. G. lucidum All. [4x] Material and methods 4–8. G. asparagifolium group 4. G. mirum Rech. f. [2x] 5. G. macedonicum Krendl [2x] The study is based on the herbarium material deposit- 6. G. rigidifolium Krendl [4x] ed in B, BP, COI, FI, G, GB, GOET, GZU, JE, LD, LI, LE, 7. G. flavescens Borbás [4x] LTR, M, PRC, SO, SOA, SOM, W, and WU, as well as on 8. G. asparagifolium Boiss. [4x] field studies and plants collected in Bulgaria in the years 9–11. G. rhodopeum group 2006, 2007 and 2008. Distribution of the species and 9. G. rhodopeum Velen. [2x, ?4x] subspecies in Bulgaria is presented by floristic regions 10. G. velenovskyi Ančev [4x] (Jordanov 1966). The species groups are informal, used 11. G. aegeum (Stoj. & Kitan.) Ančev [4x] for convenience to show very close morphology and probable phylogenetic relations between the species 12–14. G. glaucum group within the group (Greuter & al. 1986; Greuter 2008). 12. G. octonarium (Klokov) Pobed. [2x] The chromosome numbers were counted by both au- 13. G. glaucum L. [4x] thors (Appendix 2). Karyotypes analysed by M. Anchev 14. G. volhynicum Pobed. [?2n] were observed on mitotic metaphase plates, obtained 15–18. G. sylvaticum group from seedling root tips and flower buds, the latter col- 15. G. pseudoaristatum Schur [2x] lected in the field and fixed in Carnoy´s, then stained 16. G. paschale Forsskål [2x] with acetocarmine immediately before squashing. The 17. G. procurrens Ehrend. [2x] root tips were fixed in 45 % acetic acid or ethanol:acetic 18. G. intermedium Schult. (G. schultesii Vest) [6x] acid (3:1), underwent hydrolizis, stained with haema- toxylin after Gomori (Melander & Wingstrand 1953), and then squashed. The chromosome numbers (2n) Variation and diagnostic characters are listed after the morphological description, and the numbers based on Bulgarian material are asterisked The morphological variation of the species members (*). A few dubious numbers are preceded by a ques- of sect. Leiogalium concerns the root system, size and tion mark. The list of karyologically examined species position of the stem, number, size and form of the and the origin of the material are given in Appendix 2. leaves, position of the leaf margins toward the midrib, The number of voucher specimens marked with (+) re- form and branching of the inflorescence, length of the flect the chromosome number (metaphase I) counted flower/ fruit pedicel, form and diameter of the corolla, in flower buds. The voucher specimens have been des- form of the corolla lobes. For a correct identification posited in SOM and W. one needs plants with well preserved flowers. Phytol. Balcan. 17(3) • Sofia • 2011 293 The woody stock with a branched taproot without for those parasitic on plants”. The results of our field ob- subterranean runners are characters differentiating G. servations in plant populations of Galium in the entire lovcense (2x) from the related to it G. lucidum (4x) and country demonstrate that, with two exceptions, there narrow-leafy forms of G. album (4x). The well devel- were no plants (leaves or flowers) damaged by insects. oped taproot differentiates G. mirum (2x) from G. fla During more than four decades of field studies into vescens (4x), as well as G. octonarium (2x) from G. glau the Bulgarian flora, only in two cases the junior author cum (4x), and G. paschale (2x) from G. procurrens (2x). [here the first author] found plants of G. album subsp. The wide-leafy species, members of G. mollugo album with heavily damaged leaves – in localities along group and G. sylvaticum group, are mesophylous and the Black Sea Coast (north of the town of Varna) and in xeromesophylous plants with oblanceolate to oblong- the Rhodopi Mts (Eastern – south of Kardzhali). Cat- oblanceolate leaves. Their leaf size is a rather variable erpillars of the moth Macroglossa stellatarum (Sphingi character, more or less related to the ecological charac- dae) obviously feeded on the leaves of these plants. This teristics of the habitat. The leaf form and the position supported the known information about the members of the leaf margin, together with the form of the corol- of Rubiaceae differentiated by Merz (1959, after Ehrlich la and corolla lobes, are important characters for the & Raven 1965: 600) together with other families into the differentiation of the mesophilous and xeromesophil- group “Sphingidpflanzen”: plants fed on by moths of the ous species of G. mollugo group from the xerophilous family Sphingidae. We suppose that in Galium chemical species groups of G. rhodopeum and G. asparagifolium. compounds of the secoiridoid glycosides and triterpene The members of the G. rhodopeum group (G. rhodope