Distephanus
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Ordo: Asterales
Familia: Asteraceae
Name
Distephanus Cass., 1817 – Wikispecies link – Pensoft Profile
- Distephanus Cass. Bull. Soc. Philom. Paris 1817: 151. 1817.
- Gongrothamnus Steetz in Peters, Reise Mossamb., Bot.: 336. 1864. – Type: Gongrothamnus divaricatus Steetz in Peters
- Newtonia O. Hoffm. in Engler & Prantl, Natürl. Pflanzenfam. 4(5): 285. 1892, nom. illeg., non Baill. 1888. – Type: Newtonia angolensis O. Hoffm.
- Antunesia O. Hoffm., Bolet. Soc. Brot. 10” 178. 1893 (“1892”), nom. nov. for Newtonia.
Resources
For discussion and numerous transfers of species see treatment by Robinson and Kahn (1986)[1]. For a recent treatment of the genus in southern Africa see Swelankomo and Manning (2014)[2].
Descriptions
Shrubs or vines; hairs arachnoid, contorted or asymmetrically T-shaped. Leaves alternate; petioles short; blades ovate to rounded, often with truncate to subcordate bases, less often narrow with cuneate bases, margins usually entire or subentire, venation usually with stronger more ascending basal pair or strongly triplinervate, less often irregularly pinnate. Inflorescences terminal on stems or branches, with single heads or usually branching, corymbiform with minute bracts or thyrsoid with foliose bracts; peduncles usually short. Heads with campanulate involucres; bracts 21–24(–75) in 4–6(–7) gradate series, without appendaged tips; receptacles epaleaceous. Florets 10–16(–75) in a head; corollas usually yellow, purplish in a few continental African species; anther thecae with distinct broad often sclerified basal appendages; endothecial cells with simple, broad, non-contiguous, sclerified shields; apical appendages without glands; style base with large abruptly distinct node; style branches with obtuse sweeping hairs. Achenes cylindrical to prismatic, sometimes subtriquetrous or quadrangular, with 5–12 ribs, usually 10, setulae or glands present or absent, raphids elongate; carpopodium turbinate; pappus of many capillary bristles, outer series of squamellae. Chromosome numbers n = 9, 10, 15 (Jones 1982[3], Gill and Omoigui 1992[4]).
Pollen: 30–36 μm in diameter (dry); tricolporate, sublophate to lophate; lophate forms with muri projecting as spurs into colpus, with echinate or with nearly psilate ridges; tectum continuous in intercolpi and at poles, or in pockets surrounded by ridges, with distinct perforations; with columellae under spines or with muri granular inside, without distinct baculae (Figs 4 G–I). Notable secondary metabolites: sesquiterenes, elemanolides (Bohlmann and Jakupovic, as Gongrothamnus aurantiaca N.E. Br.), guaianolide (as Gongrothamnus sublutea Elliot., guaianolides (Bohlmann and Jakupovic 1990[5], as Vernonia anisochaetoides Sond., glaucolides/hirsutanolides (Bohlmann and Jakupovic 1990[5], as Vernonia angulifolia DC., Vernonia tufrnellae S. Moore).
Taxon Treatment
- 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
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Other References
- ↑ Robinson H, Kahn B (1986) Trinervate leaves, yellow flowers, tailed anthers and pollen variation in Distephanus Cassini (Vernonieae: Asteraceae). Proceedings of the Biological Society of Washington 99(3): 493–501. doi: 10.1098/rspb.1986.0036
- ↑ Swelankomo N, Manning J (2014) The genus Distephanus (Asteraceae: Vernonieae) in southern Africa. South African Journal of Botany 94: 38–48. doi: 10.1016/j.sajb.2014.07.007
- ↑ 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
- ↑ Gill L, Omoigui D (1992) Chromosome numbers in some Nigerian Compositae. Compositae Newsletter 20/21: 12–16. http://www.biodiversitylibrary.org/item/48998#page/14/mode/1up
- ↑ 5.0 5.1 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
