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- Polydora Fenzl, Flora 27: 312. 1844. – Type: Polydora stoechadifolia Fenzl = Webbia serratuloides DC.
- Crystallopollen Steetz in Peters, Reise Mossamb. Bot. 363. 1864. – Type: Crystallopollen angustifolium Steetz
Some species of the genus are treated by Pope (1986).
Mostly annuals; stems with L-shaped hairs bearing elongate one-armed cap-cells. Leaves alternate. Inflorescence a thyrsoid panicle with corymbiform cymose branches bearing pedunculate heads or a single terminal head. Involucral bracts ca. 80 in ca, seven series, often with widely scarious margins and awns often black at tips; receptacles epaleaceous. Florets ca. 30 in a head; corollas whitish to purplish, basal tube long, narrowly funnelform distally, throat as long as the narrow glabrous lobes; anther bases plain, not tailed; apical appendage glabrous, with thin cell walls, sometimes weakly ornamented; style base with distinct annular node; branches with acicular sweeping hairs. Achenes 5 or 8–10-ribbed, setuliferous with setulae scarcely divided at tips, idioblasts present but not grouped, raphids elongate; pappus with copious barbellate setae, greenish, yellowish or tawny, rarely white, outer pappus short, squamiform. Chromosome number n = 9, 10 (Jones 1979, 1982, Ayodele 1999).
Pollen lophate with ca. 32 lacunae, with five or more pores that seem to be rather asymmetrically distributed on the grains; the pores occur in lacunae that, in a few cases, are adjacent; margins of muri minutely echinate to psilate, without micropunctations, baculae closely spaced in single evenly spaced row under each murus, baculae in turn subtended by “rhizomate” structure that is weakly attached to the footlayer, the muri thus easily stripping away from the footlayer (Fig. 22 C). The pollen of Polydora proves to have a lophate condition with well-defined lophae or muro bearing 4–5 spinules on each segment. The lophae are subtended by columellae in a single series not leaving an ogee-shaped gap in the middle.
Notable secondary metabolites: sesquiterpene lactone glaucolides/hirsutanolies (Bohlmann and Jakupovic 1990, as Vernonia poskeana Vatke & Hildebr.), elemanolides, eudesmanolides, secoglaucolides (Herz 1996, as Vernonia poskeana Vatke & Hildebr. Polydora angustifolia is the species with which Steetz first introduced the use of pollen structure in the taxonomy of the Asteraceae (Steetz in Peters 1864). The generic name Crystalopollen was based on the lophate pattern of the pollen observed by Steetz.
- Robinson, H; Skvarla, J; Funk, V; 2016: Vernonieae (Asteraceae) of southern Africa: A generic disposition of the species and a study of their pollen PhytoKeys, (60): 49-126. doi
- Pope G (1986) Vernonia chloropappa (Compositae) and related species in tropical Africa. Kew Bulletin 41: 393–397. doi: 10.2307/4102946
- Jones S (1979) Chromosomes of the Vernonieae (Compositae). Bulletin of the Torrey Botanical Club 106: 79–84. doi: 10.2307/2484281
- Jones S (1982) Pp. 126–127 In: Löve A (Ed.) IOPB Chromosome number reports LXXIV. Taxon 31: 119–128. http://www.jstor.org/stable/1219710?seq=1#page_scan_tab_contents
- Ayodele M (1999) Karyomorphological studies in some Nigerian species of Vernonia Schreb. (Asteraceae) with different growth forms. Feddes Repertorium 110: 7–8. doi: 10.1002/fedr.19991100715
- Bohlmann F, Jakupovic J (1990) Progress in the chemistry of the Vernonieae (Compositae). Plant Systematics and Evolution Suppl. 4: 3–43. doi: 10.1007/978-3-7091-6928-5_2
- Herz W (1996) A review of the terpenoid chemistry of the Vernonieae. In: Hind D Beentje H (Eds) Compositae: Systematics. Proceedings of the International Compositae Conference, Kew, 1994. Royal Botanic Gardens, Kew, 229–251.