Common Name: DOGBANE FAMILY
Habit: Annual, perennial herb, shrub, tree, often vine; sap generally milky. Leaf: simple, alternate, opposite, subwhorled to whorled, entire; stipules 0 or small, finger-like. Inflorescence: axillary or terminal, cyme, generally umbel- or raceme-like, or flowers 1--2. Flower: bisexual, radial; perianth parts, especially petals, overlapped, twisted to right or left, at least in bud; sepals generally 5, fused at base, often reflexed, persistent; petals generally 5, fused in basal +- 1/2; stamens generally 5, attached to corolla tube or throat, alternate lobes, free or fused to form filament column and anther head, filament column then generally with 5 free or fused, +- elaborate appendages abaxially, pollen +- free or removed in pairs of pollinia; nectaries 0 or near ovaries, then 2 or 5, or in stigmatic chambers; ovaries 2, superior or +- so, free [fused]; style tips, stigmas generally fused into massive pistil head. Fruit: 1--2 follicles, (capsule), [berry, drupe]. Seed: many, often with tuft of hairs at 1 or both ends.
Genera In Family: 200--450 genera, 3000--5000 species: all continents, especially tropics, subtropical South America, southern Africa; many ornamental (including Asclepias, Hoya, Nerium, Plumeria, Stapelia); cardiac glycosides, produced by some members formerly treated in Asclepiadaceae, used as arrow poisons, in medicine to control heart function, and by various insects for defense. Note: Asclepiadaceae ("asclepiads"), although monophyletic, included in Apocynaceae because otherwise the latter is paraphyletic. Complexity of floral structure, variation in asclepiads arguably greatest among all angiosperms. Pattern of carpel fusion (carpels free in ovule-bearing region, fused above), present +- throughout Apocynaceae (in broad sense), nearly unknown in other angiosperms. Base chromosome number generally 11; abundance of latex, generally small size of chromosomes evidently have impeded cytological investigations.
eFlora Treatment Author: Thomas J. Rosatti, except as noted
Scientific Editor: Bruce G. Baldwin.
Species In Genus: 1 sp.: California. Etymology: (Greek: ring gland, from nectary)
Habit: Perennial herb, +- erect, 6--12 cm, fleshy (including large root), herbage tomentose to generally glabrous, glaucous. Leaf: opposite, 2--5 pairs, < 9 cm; petiole < to > blade; blade ovate or +- round, base +- truncate to tapered. Inflorescence: cyme, 2--6-flowered. Flower: > 15 mm; calyx lobes narrow-triangular; corolla 15--20 mm, funnel-shaped, with 5 +- round appendages behind anthers, rose-purple, lobes obovate or round, margins wavy; filaments free, appearing to be attached at base of corolla tube but fused to it up to level of stigma, unappendaged, hairy, anthers forming cone around but free from stigma, each partly sterile, sharply sagittate, pollen +- free; nectaries 5, fused into a 5-lobed disk around but not exceeding ovaries; style thread-like; stigma skirted at base. Fruit: 3--5 cm. Seed: with tuft of long hairs at 1 end. Chromosomes: 2n=14.
Note: Varieties possibly untenable, merit study.
Unabridged Note: Given that hairiness within Cycladenia humilis var. humilis appears to be governed by a single gene (thus reducing Cycladenia humilis var. tomentosa to synonymy under Cycladenia humilis var. humilis), doubt is cast on the hair characters separating Cycladenia humilis var. humilis from Cycladenia humilis var. venusta and Cycladenia humilis var. jonesii as well; given that corolla lobe length in Cycladenia humilis var. humilis overlaps that in Cycladenia humilis var. venusta and Cycladenia humilis var. jonesii, doubt is cast on the characters separating these varieties as well. Therefore, the entire group merits further study.