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Systematics and Phytogeography |
Department of Biology and Microbiology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin 54901 USA
Received for publication July 18, 2000. Accepted for publication December 14, 2000.
| ABSTRACT |
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Key Words: Brighamia Campanulaceae Cyanea Delissea Lobelioideae scanning electron microscopy seed coat morphology
| INTRODUCTION |
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1200 species assigned to 29 currently recognized genera (T. G. Lammers, unpublished data). In recent years, much taxonomic attention has been focused on the subfamily, due to the growing realization that its existing classification (Wimmer, 1943, 1953, 1968
Among the various types of nonmolecular data germane to Lobelioideae, seed coat morphology appears to be of great value. Compared to many vegetative and floral structures, seed coat morphology shows very little plasticity; variation among individuals and taxa almost certainly reflects genetic and phylogenetic differences (Barthlott, 1984
). McVaugh (1936, 1940a, b, 1943)
relied heavily on seed coat characters in distinguishing genera and infrageneric groupings of North American lobelioids. More recently, Murata (1992, 1995)
has examined a diversity of lobelioid seeds via scanning electron microscopy (SEM). The testal characters he emphasized correlated well with certain vegetative and floral features (e.g., habit, anther trichomes), as well as with additional data not available to Wimmer (1943, 1953, 1968)
, i.e., chromosome numbers (Lammers, 1993
) and chloroplast genome rearrangements (Knox, Downie, and Palmer, 1993
). Synthesis of these data led to a revision of the supraspecific classification of the largest genus in the subfamily, Lobelia L. (Murata, 1995
).
The objective of the present study was to extend Murata's surveys to lobelioid genera in which he examined few or no species. Particular emphasis was placed on genera endemic to the Hawaiian Islands (Lammers, 1988, 1989, 1990, 1991, 1995
), especially Cyanea Gaudich. (including Rollandia Gaudich.; cf. Lammers, Givnish, and Sytsma, 1993
), as these plants recently have been the focus of detailed molecular phylogenetic studies (Givnish et al., 1994, 1995, 1996a, b
). As noted by Givnish et al. (1995)
, the clades revealed by these analyses correlate very poorly with previous sectional classifications (Hillebrand, 1888
; Rock, 1919
; Wimmer, 1943
); the vegetative and floral characters used by earlier authors to characterize taxonomic sections do not distinguish the molecularly based clades. It thus was anticipated that seed morphology could offer a nonmolecular basis for their recognition. Seeds of additional non-Hawaiian lobelioids were likewise examined with an eye towards answering various other taxonomic questions that have arisen over the years.
| MATERIALS AND METHODS |
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8 nm of gold/palladium and examined in a Hitachi 2460N SEM at 25 kV, 20 mm working distance, and a consistent spot size. The resulting images were recorded on Polaroid type 55 film. Magnification was verified by photographing a calibration standard (Ladd Research Industries, Burlington, Vermont, USA) at the same instrument settings used for viewing seed samples. | RESULTS |
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| DISCUSSION |
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Until recently, it was believed that the Hawaiian Lobelioideae were polyphyletic, i.e., that they were the evolutionary result of multiple introductions to the archipelago from continental source areas via long-distance dispersal (Rock, 1919
; Brown, 1921
; Skottsberg, 1928
; Stone, 1967
; Carlquist, 1974
; Lammers and Freeman, 1986
; Lammers, 1988, 1990
). This hypothesis was based on differences in the morphology of inflorescences, flowers, and fruits. A single introduction was hypothesized for Clermontia, Cyanea, and Delissea, the three genera with axillary inflorescences, curved bilabiate or unilabiate corollas, and fleshy indehiscent fruits. A second extra-Hawaiian ancestor was hypothesized for Brighamia, which also has axillary inflorescences, but straight salverform corollas and dry dehiscent fruits (albeit fleshy-walled at first). Finally, one to three additional origins were proposed for the taxa with terminal inflorescences, curved bilabiate or unilabiate corollas, and dry dehiscent fruits: the two sections of Lobelia plus Trematolobelia.
In contrast to these morphological data, phylogenetic analyses of molecular data (Givnish et al., 1995, 1996a
; E. Knox, Rutgers University, personal communication) strongly support the monophyly of the Hawaiian lobelioids. These data indicate that all six genera evolved from a single colonization of the archipelago. Within this lineage, Delissea is not allied to Clermontia-Cyanea, as suggested by morphology, but rather is sister to Brighamia. The Brighamia-Delissea clade is then the sister-group of Clermontia-Cyanea. Because Trematolobelia and the two sections of Lobelia form the basal branches of the Hawaiian clade, it has been hypothesized (Knox, Downie, and Palmer, 1993
; Givnish et al., 1995, 1996a
) that the extra-Hawaiian progenitor of the Hawaiian Lobelioideae was most likely an Asian species referable to Lobelia subg. Tupa, with terminal inflorescences, curved bilabiate or unilabiate corollas, and dry dehiscent fruits. Our seed data offer support for various aspects of these molecular findings.
Origin of the Hawaiian Lobelioideae
All Hawaiian Lobelioideae examined have either Type C seeds or unique testal patterns that appear to be modified from a Type C pattern (i.e., Type F and Type G). This uniformity of testal pattern supports the monophyly of the Hawaiian Lobelioideae. If the Hawaiian lobelioids in fact stemmed from three to five independent introductions, one might expect at least some of the genera to show other testal patterns.
Outside the Hawaiian Islands, Type C seeds have been reported only from certain members of Lobelia subg. Tupa, specifically Asian species of sect. Colensoa (Hook. f.) Murata and African species of sect. Rhynchopetalum (Fresen.) Benth. (Murata, 1992, 1995
). In the molecular analysis of Knox, Downie, and Palmer (1993)
, all Type C species fell into a single clade that was sister to the remainder of the subfamily; no other seed coat type was found within this clade (Murata, 1995
). Thus, on the basis of seed morphology alone, one might hypothesize that the ancestor of the Hawaiian lobelioids would be referable to these members of Lobelia subg. Tupa. In fact, Asian species of sect. Colensoa (e.g., L. nicotianifolia Roth ex Schult.) are very similar to sect. Revolutella in overall morphology (Rock, 1919
; Skottsberg, 1928
; Stone, 1967
; Carlquist, 1974
; Lammers, 1990
) and have been particularly implicated as ancestors of the Hawaiian lobelioids on the basis of recent molecular data (Knox, Downie, and Palmer, 1993
; Givnish et al., 1995, 1996a
). Earlier suggestions that the fleshy-fruited genera in Hawaii (Clermontia, Cyanea, Delissea) are derived from South American species of Centropogon (Hemsley, 1885
; Drake del Castillo, 1890
; Guppy, 1906
; Rock, 1919
; Brown, 1921
; Wimmer, 1943
; Stone, 1967
; Carlquist, 1974
) are not supported by our data. As noted below, all species of Centropogon that have been examined have Type B seed coats.
Relationship of Brighamia to Delissea
The unique Type G testal pattern found in Brighamia and Delissea supports the close relationship between these two genera revealed by the molecular analyses. It argues against a close relationship between Delissea on the one hand and Clermontia and Cyanea on the other (Rock, 1919
; Stone, 1967
; Carlquist, 1974
; Lammers, 1988, 1990
) and against the proposed merger of Cyanea and Delissea (St. John, 1987
; St. John and Takeuchi, 1987
). In addition to testal pattern, seeds of Brighamia and Delissea differ from all other Hawaiian Lobelioideae in their white color and large size (Hillebrand, 1888
; Rock, 1919
; Wimmer, 1943
; Lammers, 1990
; Givnish et al., 1995
); seeds of the other genera are dark brown or black and only one-half to one-third as large. These three traits collectively, then, offer morphological synapomorphies for the convenient recognition of a clade detected by molecular means.
Previous workers (Rock, 1919
; Degener, 1937
; Stone, 1967
; St. John, 1969a
) have suggested that Brighamia was derived from Isotoma (R. Br.) Lindl. (11 species endemic to Australia; Lammers, 1999a
) or Hippobroma (see below), based on their common possession of an unusual salverform corolla. Seed morphology will support neither of these hypotheses: Murata (1995)
reported Type B seeds in the one species of Isotoma he examined, while Type E is reported here for Hippobroma (see below).
Sectional relationships within Cyanea
Cyanea was the only genus examined in which two distinct testal patterns were observed. Twenty-one of the 26 accessions showed Type C morphology, as reported by Murata (1995)
for C. kunthiana. The species with this seed type belonged to four of the five sections recognized by Rock (1919)
: sect. Cyanea (C. grimesiana subsp. grimesiana, C. horrida, C. longissima, C. platyphylla, C. shipmanii), sect. Hirtellae Rock (C. hirtella, C. kuhihewa, C. membranacea), sect. Palmiformes (Hillebr.) Rock (C. hamatiflora subsp. hamatiflora, C. leptostegia, C. macrostegia, C. solenocalyx, C. truncata), and sect. Pilosae Rock (C. acuminata, C. copelandii subsp. copelandii, C. floribunda, C. kunthiana, C. stictophylla). The species formerly segregated (Hillebrand, 1888
; Rock, 1919
; Wimmer, 1943
; Stone, 1967
; Lammers, 1990
) as Rollandia (C. calycina, C. humboldtiana, C. longiflora) also had this type seed, data that further support their merger (Lammers, Givnish, and Sytsma, 1993
). Type C seeds were also found in species belonging to five of the six molecularly based clades recognized by Givnish et al. (1995)
: the four sublineages making up the Orange-fruited Clade, plus the Leptostegia Clade within the Purple-fruited Clade.
The remaining five accessions showed the Type F testal pattern, characterized by rounded, knob-like protuberances on the radial walls at the opposite ends of the cells. All five are referable to sect. Delisseoideae (Hillebr.) Rock, and three (C. angustifolia, C. coriacea, and C. hardyi) have been included in molecular-based phylogenetic analyses (Givnish et al., 1994, 1995
). Together with C. spathulata (Hillebr.) A. Heller (for which we were unable to obtain mature seed), they formed the Hardyi Clade, the other sublineage within the Purple-fruited Clade. The other two species with this seed type, C. fauriei and C. "pseudofauriei," were not included in the molecular analyses, but would appear referable to the Hardyi Clade based on their resemblance to C. coriacea and C. hardyi in various characters. This unique seed coat pattern thus offers a morphological marker for the recognition of the Hardyi Clade. In a formal classification, the name sect. Delisseoideae would be available for this clade, as C. angustifolia is its lectotype (St. John, 1969b
).
Distinctness of Centropogon and Siphocampylus
These two large neotropical genera are very similar overall and frequently confused by collectors. The only character by which they can be distinguished is fruit type: fleshy indehiscent berries in the former, dry apically dehiscent capsules in the latter (Wimmer, 1943, 1953
; Lammers, 1998a
). Preliminary molecular studies (Pepper, Gustafsson, and Albert, 1997
) indicate that this is not a sound basis for recognition, as species of the two genera are interdigitated throughout the resulting cladograms. It appears that Centropogon is polyphyletic, having arisen at several points within Siphocampylus through an apparently simple shift from capsular to baccate fruit.
The four species of Centropogon and five species of Siphocampylus examined confirm Murata's (1995)
previous findings of Type B seeds in one species of each genus. Despite having what would seem to be very different types of fruit, the seeds of the two genera are of the same type. Given the large size of these genera (216 species each), our data are far from comprehensive. However, they do offer some support for the hypothesis that Centropogon and Siphocampylus are closely related if not congeneric.
Affinities of Legenere
Legenere comprises a single annual species amphitropically distributed in ephemeral wetland habitats in California, Chile, and Argentina (Ruiz de Ciolfi, 1976
). Although Wimmer (1953)
considered it taxonomically isolated within the family, relegating it to the monotypic subtribe Legenerinae E. Wimm., recent molecular studies (Schultheis and Baldwin, 1997
) have shown that it forms a clade with three other western North American genera of annual plants growing in similar habitats: Downingia Torr. (also found in Chile and Argentina), Howellia A. Gray, and Porterella Torr. Our finding of Type D seeds in Legenere offers some support of this hypothesis. Murata (1995)
reported this type of seed in one species of Downingia, and earlier line drawings of Downingia seeds executed via light microscopy (McVaugh, 1941
, figs. 1416) also appear to represent the Type D testal pattern.
Affinities of Hippobroma
Hippobroma comprises a single species originally endemic to Jamaica but now found throughout much of the tropics (McVaugh, 1940a
). As noted above, the genus has been thought to be allied to Brighamia or Isotoma, primarily due to its unusual salverform corolla (Wimmer, 1953
; Stone, 1967
; St. John, 1969a
). Our finding of Type E seeds in Hippobroma does not support that hypothesis. Brighamia has the new Type G testal type (Figs. 12), while the one species of Isotoma examined by Murata (1995)
had Type B seeds.
The only lobelioid reported by Murata (1995)
that had Type E seeds was Lobelia grandifolia Britt. of Jamaica. Although Murata (1995)
assigned that species to sect. Pratia (Gaudich.) Murata, it is better accommodated in sect. Tylomium (C. Presl) Benth. (Adams, 1972
; Wilbur, 1991
; Lammers and Proctor, 1994
), a group characterized by bilabiate or unilabiate curved corollas. Because these are the only two species known with Type E seeds, it is reasonable to hypothesize that they are closely related. Just as in Hawaii, salverform Brighamia appears to be most closely related to bilabiate/unilabiate Delissea, so too do our data suggest that in the West Indies, salverform Hippobroma appears to be most closely related to bilabiate/unilabiate Lobelia sect. Tylomium.
Summary
Seed coat morphology continues to prove useful in understanding systematic relationships within the Lobelioideae. In particular, testal patterns may offer hallmarks for the convenient recognition and description of clades revealed by phylogenetic analysis of DNA sequences and other molecular characters. Though the surveys of Murata (1992, 1995)
were extensive, they were not exhaustive; two new testal patterns were discovered within the Hawaiian clade of the subfamily and additional patterns may remain to be uncovered.
| FOOTNOTES |
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2 Author for reprint requests (lammers{at}uwosh.edu
). ![]()
| LITERATURE CITED |
|---|
|
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|---|
Ayers T. J. 1990 Systematics of Heterotoma (Campanulaceae) and the evolution of nectar spurs in the New World Lobelioideae. Systematic Botany 15: 296-327[CrossRef][ISI]
Barthlott W. 1984 Microstructural features of seed surfaces. In V. H. Heywood and D. M. Moore [eds.], Current concepts in plant taxonomy, 95105. Academic Press, London, UK
Brown F. B. H. 1921 Origin of the Hawaiian flora. Special Publications, Bernice Pauahi Bishop Museum 7: 131-142
Carlquist S. 1974 Island biology. Columbia University Press, New York, New York, USA
Degener O. 1937 Brighamia. In Flora Hawaiiensis, fam. 339. Published privately, Honolulu, Hawaii, USA
Dotti K. D. T. J. Ayers 1997 Resolving the phylogeny of the genus Lysipomia (Campanulaceae) using nuclear ribosomal internal transcribed spacer (ITS) sequences. American Journal of Botany 84: (6, Supplement) :188 (Abstract)
Drake del Castillo E. 1890 Remarques sur la flore de la Polynésie et sur rapports avec celle de terres voisines. G. Masson, Paris, France
Givnish T. J. E. Knox T. B. Patterson J. R. Hapeman J. D. Palmer K. J. Sytsma 1996a The Hawaiian lobelioids are monophyletic and underwent a rapid initial radiation roughly 15 million years ago. American Journal of Botany 83: (6, Supplement) 159 (Abstract)
, K. J. Sytsma T. B. Patterson J. R. Hapeman 1996b Comparison of patterns of geographic speciation and adaptive radiation in Cyanea and Clermontia (Campanulaceae) based on a cladistic analysis of DNA sequence and restriction-site data. American Journal of Botany 83: (6, Supplement) 159 (Abstract)
, , J. F. Smith W. J. Hahn 1994 Thorn-like prickles and heterophylly in Cyanea: adaptations to extinct avian browsers on Hawaii?. Proceedings of the National Academy of Science, USA 91: 2810-2814
, , , and . 1995 Molecular evolution, adaptive radiation, and geographic speciation in Cyanea (Campanulaceae, Lobelioideae). In W. L. Wagner and V. A. Funk [eds.], Hawaiian biogeography: evolution on a hot spot archipelago, 288337. Smithsonian Institution Press, Washington, D.C., USA
Grant V. 1998 Primary classification and phylogeny of the Polemoniaceae, with comments on molecular cladistics. American Journal of Botany 85: 741-752[Abstract]
Guppy H. B. 1906 Observations of a naturalist in the Pacific between 1896 and 1899, vol.2. MacMillan, New York, New York, USA
Hemsley W. B. 1885 Report on present state of knowledge of various insular floras. In Report of the scientific results of the voyage of H. M. S. Challenger during the years 187376, Botany, vol. 1, 175. Her Majesty's Stationery Office, London, UK
Hillebrand W. 1888 Flora of the Hawaiian Islands. Williams & Norgate, London, UK
Holmgren P. K. N. H. Holmgren L. C. Barnett 1990 Index herbariorum, part I: The herbaria of the world. New York Botanical Garden, Bronx, New York, USA
Knox E. B. S. R. Downie J. D. Palmer 1993 Chloroplast genome rearrangements and the evolution of giant lobelias from herbaceous ancestors. Molecular Biology and Evolution 10: 414-430[ISI]
, and J. D. Palmer 1998 Chloroplast DNA evidence of the origin and radiation of the giant lobelias in eastern Africa. Systematic Botany 23: 109-149
Lammers T. G. 1988 Chromosome numbers and their systematic implications in Hawaiian Lobelioideae (Campanulaceae). American Journal of Botany 75: 1130-1134[CrossRef][ISI]
. 1989 Revision of Brighamia (Campanulaceae: Lobelioideae), a caudiciform succulent endemic to the Hawaiian Islands. Systematic Botany 14: 133-138
. 1990 Campanulaceae. In W. L. Wagner, D. R. Herbst, and S. H. Sohmer [eds.], Manual of the flowering plants of Hawai'i, 420489. University of Hawaii Press, Honolulu, Hawaii, USA
. 1991 Systematics of Clermontia (Campanulaceae-Lobelioideae). Systematic Botany Monographs 32: 1-97
. 1993 Chromosome numbers of Campanulaceae. III. Review and integration of data for subfamily Lobelioideae. American Journal of Botany 80: 660-675[CrossRef][ISI]
. 1994 Typification of the names of Hawaiian Lobelioideae (Campanulaceae) published by Wilhelm Hillebrand or based upon his specimens. Taxon 43: 545-572[CrossRef][ISI]
. 1995 Patterns of speciation and biogeography in Clermontia (Campanulaceae, Lobelioideae). In W. L. Wagner and V. A. Funk [eds.], Hawaiian biogeography: evolution on a hot spot archipelago, 338362. Smithsonian Institution Press, Washington, D.C., USA
. 1996 A new linear-leaved Cyanea (Campanulaceae: Lobelioideae) from Kaua'i, and the "rediscovery" of Cyanea linearifolia. Brittonia 48: 237-240[CrossRef][ISI]
. 1998a Review of the neotropical endemics Burmeistera, Centropogon, and Siphocampylus (Campanulaceae: Lobelioideae), with description of 18 new species and a new section. Brittonia 50: 233-262[CrossRef][ISI]
. 1998b New names and new combinations in Campanulaceae. Novon 8: 31-35[CrossRef][ISI]
. 1999a Nomenclatural consequences of the synonymization of Hypsela reniformis (Campanulaceae: Lobelioideae). Novon 9: 73-76
. 1999b A new Lobelia from Mexico, with additional new combinations in world Campanulaceae. Novon 9: 381-389[CrossRef][ISI]
, and C. E. Freeman 1986 Ornithophily among the Hawaiian Lobelioideae (Campanulaceae): evidence from floral nectar sugar compositions. American Journal of Botany 73: 1613-1619[CrossRef][ISI]
, T. J. Givnish K. J. Sytsma 1993 Merger of the endemic Hawaiian genera Cyanea and Rollandia (Campanulaceae: Lobelioideae). Novon 3: 437-441
, and G. R. Proctor 1994 Lobelia vivaldii (Campanulaceae: Lobelioideae), a remarkable new species of sect. Tylomium from Isla de Mona, Puerto Rico
McVaugh R. 1936 Studies in the taxonomy and distribution of the eastern North American species of Lobelia. Rhodora 38: 241-263,276-298,304-329,346-362
. 1940a A revision of "Laurentia" and allied genera in North America. Bulletin of the Torrey Botanical Club 67: 778-798[CrossRef]
. 1940b A key to the North American species of Lobelia (sect. Hemipogon). American Midland Naturalist 24: 681-702[CrossRef]
. 1941 A monograph of the genus Downingia. Memoirs of the Torrey Botanical Club 19: 1-57
. 1943 Campanulaceae (Lobelioideae). North American Flora 32A: 1-134
Murata J. 1992 Systematic implications of seed coat morphology in Lobelia (Campanulaceae-Lobelioideae). Journal of the Faculty of Science, University of Tokyo (Section 3) 15: 155-172
. 1995 A revision of infrageneric classification of Lobelia (Campanulaceae-Lobelioideae) with special reference to seed coat morphology. Journal of the Faculty of Science, University of Tokyo (Section 3) 15: 349-371
Pepper A. S.-R. M. H. G. Gustafsson V. A. Albert 1997 Molecular systematics of neotropical Lobelioideae (Campanulaceae), with emphasis on Burmeistera, Centropogon, and Siphocampylus, and the utility of fruit and floral characters in lobelioid classification. American Journal of Botany 84: (6, Supplement) 222 (Abstract)
Ruiz de Ciolfi E. N. 1976 Legenere McVaugh (Campanulaceae) nueva cita para la Argentina. Boletín de la Sociedad Argentina de Botánica 17: 176-178
Rock J. F. 1919 A monographic study of the Hawaiian species of the tribe Lobelioideae family Campanulaceae. Memoirs of the Bernice Pauahi Bishop Museum 7: i-xvi,1-395
Rosatti T. J. 1986 The genera of Sphenocleaceae and Campanulaceae in the southeastern United States. Journal of the Arnold Arboretum 67: 1-64[ISI]
Schultheis L. M. B. G. Baldwin 1997 Systematics of Downingia (Campanulaceae): a preliminary investigation based on nuclear rDNA ITS data. American Journal of Botany 84: (6, Supplement) 230 (Abstract)
Serra L. M. B. Crespo T. G. Lammers 1999 Wimmerella, a new South African genus of Lobelioideae (Campanulaceae). Novon 9: 414-418[CrossRef][ISI]
Skottsberg C. 1928 On some arborescent species of Lobelia from tropical Asia. Acta Horti Gothoburgensis 4: 1-26
St. John H. 1969a Monograph of the genus Brighamia. Journal of the Linnean Society, Botany 62: 187-204
. 1969b Types of sections in Clermontia, Cyanea, and Delissea (Lobeliaceae). Taxon 18: 483
. 1987 Enlargement of Delissea (Lobeliaceae). Hawaiian plant studies 138. Phytologia 63: 79-90
, and W. Takeuchi 1987 Are the distinctions of Delissea valid? Hawaiian plant studies 137. Phytologia 63: 129-130
Stone B. C. 1967 A review of the endemic genera of Hawaiian plants. Botanical Review 33: 216-259
Wilbur R. L. 1991 Synopsis of the Mexican and Central American representatives of Lobelia sect. Tylomium (Campanulaceae-Lobelioideae). Sida 14: 555-567
Wimmer F. E. 1943 Campanulaceae-Lobelioideae, I. Teil. In R. Mansfeld [ed.], Das Pflanzenreich, IV. Teil, Abteilung 276b, ivi, 1260. Wilhelm Engelmann, Leipzig, Germany
. 1953 Campanulaceae-Lobelioideae, II Teil. In H. Stubbe and K. Noack [eds.], Das Pflanzenreich, IV. Teil, Abteilung 276b, iviii, 261813. Akademie Verlag, Berlin, Germany
. 1968 Campanulaceae-Lobelioideae supplementum et Campanulaceae-Cyphioideae. In S. Danert [ed.], Das Pflanzenreich, IV. Teil, Abteilung 276c, ix, 8151024. Akademie Verlag, Berlin, Germany
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