Orchid seed diversity: a scanning electron microscopy survey / Wilhelm Barthlott, Bernadette Grobe-Veldmann, Nadja Korotkova

Incluye bibliografía: páginas 213-216 e índice: páginas 239-245

Summary and key words.. preface and acknowledgements.. Introduction.. current knowledge of orchid phylogeily.. Seeds of orchids.. Earlier seed morphology studies in Orchidaceae.. Aims of this study.. Descriptors and ternlinology.. Seed characters.. Seed shape.. Seed size (length of seed.. Seed colour.. Number of testa cells (along longitudinal axis of seed.. Shape of individual testa cells.. Testa cell pattem.. Anticlinal wall curvature.. Transverse anticlinal walls.. Intercellular gaps.. Surface structure of periclinal walls.. Cuticular layer.. Modifications of testa cell comers.. Seed types.. Material and methods.. Seed material.. Taxonomiccoverage.. Scanning electron microscopy (SEM.. Orchidaceae systematics.. Character coding.. Tracing of characters.. Seed descriptions.. Apostasioideae.. Vanilloideae.. Pogonieae.. Vanilleae.. Cypripedioideae.. Orchidoideae Chloraeeae.. Codonorchideae.. Cranichideae.. Cranichidinae.. Galeottiellinae.. Goodyerinae.. Manniellinae.. Pterosiylidinae.. Spiranthinae.. Diseae.. Brownleeinae.. Coryciinae.. Disinae.. Huttonaeinae.. Saiyriinae.. Diurideae.. Acianthinae.. Caladeniinae.. Cryptosiylidinae.. Diuridinae.. Drakaeinae.. Megasiylidinae.. Prasophyllinae.. Rhizanthellinae.. Thelymitrinae.. Orchideae.. Epidendroideae.. Arethuseae.. Arethusinae.. Coelogyninae.. Calypsoeae.. Collabieae.. Cymbidieae.. Catasetinae.. Coeliopsidinae.. Cymbidiinae.. Cyrtopodiinae.. Eriopsidinae.. Eulophiinae.. Maxillariinae.. Oncidiinae.. Stanhopeinae.. Vargasiellinae.. Zygopetalinae.. Epidendreae.. Bletiinae.. Chysinae.. Coeliinae.. Laeliinae.. Pleurothallidinae.. Ponerinae.. Gastrodieae.. Malaxideae.. Neottieae.. Newilieae.. Epipogiinae.. Newiliinae.. Podochileae.. Eriinae.. Thelasinae.. Sobralieae.. Triphoreae.. Diceratostelinae.. Triphorinae.. Tropidieae.. Xerorchideae.. Vandeae.. Aeridinae.. Aerangidinae.. Angraecinae.. Polystachyinae.. Epidendroideae unplaced genera.. Discussion

The systematic and diagnostic value and evolution of orchid seed characters.. Are orchid seeds systematically relevant?. Earlier evidence from comparative studies.. Are orchid seeds systematically relevant?. Earlier evidence from cladistic studies.. Surnmary of the character reconstruction.. Concluding remarks.. SEM micrographs.. Selected seed characters visualized on phylogenetic trees.. Seed shape.. Seed size.. Seed colour.. Number of testa cells.. Shape of testa cells.. Testa cell pattem.. Anticlinal wall curvature.. Transverse anticlinal walls.. Intercellular gaps.. Ridges on periclinal walls.. Verrucosities on periclinal walls.. Perforations on periclinal walls.. Cuticular layer.. Waxcaps.. Testa cell extensions.. Seed types.. References.. Appendix: Sources of material.. Index

The Orchidaceae with some 22000 species is one of the two largest plant families. Despite of the vast literature on orchids, rather little is known about their seeds, which are generally considered as wind dispersed, small and reduced "dust seeds". Based on some 1400 collections of orchid seeds analysed by SEM and other methods over the last four decades, about 7000 micrographs of some 1100 species from 352 (out of c. 880) genera were evaluated for this first monograph on orchid seeds. Orchid seeds exhibit an astonishing diversity. This is not only reflected in their sizes (between 0.1 mm in Oberonia and 6 mm in Epidendrum) and shapes, but especially in the complexity of their lightweight seed-coat architecture and hierarchical surface sculpturing. A consistent terminology for characters of the orchid seed coat is proposed. Taxa at subtribal to tribal levels are often well characterized by seed-coat characters. Fifteen selected characters were mapped on well-supported molecular phylogenetic trees and were found to be largely consistent with the major clades. Combinations of characters classified into 17 seed types often delimit tribes (e.g. Cymbidieae, Epidendreae, Vandeae). Highly specialized features like polyembryony (up to 12 ernbryos per seed in Thecostele) or highly adaptive (with respect to dispersal biology) seed-coat features (e.g. in Galeola, or the sophisticated seed-attachment mechanism of Chiloschista) are restricted to only a few genera. This monograph provides a first atlas (624 micrographs) and data to identify the major groups of orchid seeds and a terminology for taxonomic purposes. The first character reconstmction of seed characters based on modern molecular phylogenetic hypotheses allows an application for further systematic studies of the family. eng