Figure - available from: Oesterreichische Botanische Zeitschrift
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Astraea subcomosa: a flowering branch, b detail of indumentum of younger portion of stems, c detail of stipules, d abaxial surface of leaf base, e detail of leaf margin, f pistillate flower, g calyx lobe of a pistillate flower—internal face, h calyx lobe of a pistillate flower—external face, i gynoecium and floral nectaries (calyx removed), j staminate cymules with one mature flower, k immature fruit, l seed—ventral face. Drawing by Klei Sousa from R. Mello-Silva 2703 (SP)
Source publication
Astraea is a genus of tribe Crotoneae (Euphorbiaceae: Crotonoideae) widely distributed in the Neotropical region. Its highest diversity is found in eastern Brazil, and a few weedy species were most likely introduced and naturalized in the Paleotropics. Species of Astraea may be recognized by the usually deeply lobed leaves, lacking basilaminar or a...
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Dalechampia is a mainly South American genus of generally climbing shrubs with usually sharp stiff trichomes in some of the inflorescence parts. The bisexual inflorescences are very condensed and subtended by two, often showy, large bracts. The three pistillate flowers are separate from the staminate subinflorescence (both groups with their own bra...
Citations
Trichomes are key functional traits that protect plants against abiotic stresses, herbivores and pathogens. In addition to their ecological roles, trichomes show high morphological variability in many lineages, providing useful characters for species characterization and taxon delimitation. Here, we focus on trichomes in Croton, a megadiverse genus (c. 1200 spp.) of Euphorbiaceae, in which these structures are ubiquitous and exhibit significant variation in form, location on the plant body, density and function. Owing to their functional and taxonomic relevance and the current need for further standardization of their terminology and classification, we revised previous trichome classifications used in the genus. We also provide new trichome data by expanding taxon sampling and using different methodological approaches in plant anatomy to improve understanding of the structural patterns of the trichome types present in the genus. On the basis of our results and literature review, we propose a new classification for trichomes in Croton based on well-defined parameters; this clarifies existing redundancies, is consistent with anatomical evidence and can be easily updated as new types are revealed in future surveys. This contribution will improve communication among taxonomists and promote more meaningful morphological comparability across systematics studies, including those focusing on morphological evolution and functional traits.
