Family Apocynaceae
Synonyms: Asclepiadaceae APNI*
Periplocaceae APNI*
Description: Trees, shrubs, climbers with twining stems or occasionally erect or trailing herbs; latex present, usually milky but sometimes watery.
Leaves simple, entire, opposite or whorled, rarely alternate; stipules absent.
Flowers in cymes or racemes or solitary in axils; bisexual, actinomorphic. Sepals 5, usually shortly fused, often with small glands inside near the base. Corolla tubular, 5-lobed; lobes spreading. Stamens 5, epipetalous; anthers enclosed in the corolla tube or exserted, free or cohering in a cone or ring around the style. Ovary superior or rarely half-inferior, carpels 2, either the carpels free but the styles fused and the placentas marginal, or the carpels fused, the ovary then either 2-locular with axile placentas or l-locular with 2 parietal placentas; ovules usually numerous, sometimes few; style usually dilated near the apex, the swollen style head sometimes adhering to the anthers; stigma not obvious, mostly on the undersurface of the style head.
Fruit a pair of follicles, drupes or berries (sometimes only 1 of the pair developing) or a single capsule, berry or drupe; seeds sometimes with a coma.
Distribution and occurrence: World: 380 gen., 4700 spp., mainly trop. & subtrop. regions. Aust.: 55 gen., c 200 spp., all States; mainly in rainforest in the east but some species widespread in arid areas.
External links:
Angiosperm Phylogeny Website (Family: Apocynaceae, Order: Gentianales)
Wikipedia Several species are sources of drugs used in medicine, including species of Rauvolfia which yields the alkaloid reserpine and Cerbera, Cascabela, Strophanthus and Nerium, from which cardiac glycosides are obtained. Many are toxic if ingested by animals (including humans); these include the ornamental Nerium oleander L. (Oleander) and Cascabela thevetia (L.) Lippold (Yellow Oleander). Some have been used as sources of rubber. Several are cultivated for their showy scented flowers; these include species of Allamanda, Mandevilla, Nerium, Plumeria, Cascabela, Trachelospermum and Vinca.
Text by G. J. Harden & J. B. Williams
Taxon concept:
Taxa not yet included in identification key
Acokanthera,
Orbea,
Stapelia
| | Key to the genera | |
| 1 | Pollen granular, not aggregated into pollinia | 2 |
| Pollen aggregated into pollinia | 14 |
| 2 | Leaves alternate; shrub or small tree with yellow flowers | Cascabela |
| Leaves opposite or whorled; climbers, herbs, shrubs or trees; flowers either white or pink, or if yellow then plants climbing
Back to 1 | 3 |
| 3 | Plants with sharp, stiff spines at many nodes; shrubs or scrambling climbers | Carissa |
| Plants without spines at nodes
Back to 2 | 4 |
| 4 | Erect plants, neither climbing nor trailing | 5 |
| Climbers with twining stems, or trailers
Back to 3 | 11 |
| 5 | Herbs up to c. 70 cm high; flowers solitary in the axils and the corolla more than 20 mm diam | Catharanthus |
| Shrubs or small trees more than 1 m high; flowers in cymes, the corolla usually less than 20 mm diam. or rarely more than 20 mm diam. (in Nerium)
Back to 4 | 6 |
| 6 | Fruit a drupe, less than 12 mm diam., orange or red, 1-seeded or 2–4-seeded and moniliform; leaves with apex spinose or blunt to mucronate, leaves usually less than 5 cm long | Alyxia |
| Fruit either a follicle or drupaceous (and then more than 20 mm diam., red and 1–6-seeded, not moniliform); leaves not spinose, rarely blunt or mucronate, more than 5 cm long
Back to 5 | 7 |
| 7 | Leaves leathery; flowers more than 20 mm diam | Nerium |
| Leaves more or less soft; flowers less than 20 mm diam
Back to 6 | 8 |
| 8 | Fruit a cylindrical follicle, dry and pale brown when mature, 6–24 cm long; petiole slender, mostly 8–45 mm long | Alstonia |
| Fruit narrow-ovoid to ovoid or ellipsoid, either drupaceous or tardily dehiscent, yellow-orange or red, more or less fleshy when mature, 2.5–8 cm long; petiole 1–12 mm long
Back to 7 | 9 |
| 9 | Main lateral veins of leaves subtransverse, regular, more than 11 pairs; intramarginal vein present; fruit a red drupe with 1–6 large seeds | 10 |
| Main lateral veins of leaves oblique, irregular, less than 11 pairs; intramarginal vein absent; fruit banana-shaped, yellow-orange, fleshy but finally dehiscing to expose several seeds
Back to 8 | Tabernaemontana |
| 10 | Fruit 2–3 cm long, endocarp without obvious cavities; seed single, central; leaves with lateral veins distinct on the upper surface, more or less obscure on the lower surface | Neisosperma |
| Fruit 4–8 cm long, with 2 cavities and the seeds on a flattened placenta between the cavities; leaves with lateral veins prominent on the lower surface
Back to 9 | Ochrosia |
| 11 | Flowers solitary in the leaf axils; corolla blue; low trailing herbaceous perennial | Vinca |
| Flowers in cymes or racemes; corolla white, yellow, orange or pink; climbers with twining stems
Back to 4 | 12 |
| 12 | Flowers more than 40 mm in diam., white, in racemes; ovaries free but style single in each flower; fruit a pair of follicles cohering at the tip | Mandevilla |
| Flowers less than 20 mm in diam., orange-yellow to creamy white, in cymes; ovary of 2 fused carpels, 1- or 2-locular; fruit a berry or a capsule separating when mature into 2 follicle-like segments
Back to 11 | 13 |
| 13 | Anthers included in the corolla tube, not fused; fruit a globose to ovoid or oblong berry; seeds several, embedded in pulp, lacking hairs | Melodinus |
| Anthers partially or wholly exserted and fused or cohering in a cone or ring around the style head; fruit a capsule, separating into 2 follicle-like segments; seeds numerous, each with a tuft of long silky hairs
Back to 12 | Parsonsia |
| 14 | Leafless scrambling or twining plants with long pale green succulent, jointed stems | Cynanchum |
| Plants with well-developed leaves, stems neither succulent nor jointed
Back to 1 | 15 |
| 15 | Corolla sky-blue; corona of 5 erect dark blue ribbed segments, inserted on corolla tube, free from column | Oxypetalum |
| Corolla and corona never blue; corona not as above
Back to 14 | 16 |
| 16 | Erect plants to 2 m high, neither twining nor trailing | 17 |
| Climbers with twining stems or lax, trailing plants
Back to 15 | 19 |
| 17 | Flowers less than 6 mm diam., in compact umbels; corona segments small, not spreading; corolla urceolate, lobes spreading | Marsdenia |
| Flowers 8–15 mm diam., in loose umbels; corona segments large, sac-shaped or boat-shaped, spreading, conspicuous; corolla rotate, lobes reflexed
Back to 16 | 18 |
| 18 | Corolla red, corona yellow; corona segments with an erect or curved horn arising from inner face; follicle elongated, smooth | Asclepias |
| Corolla and corona white; corona segments without a horn-like outgrowth; follicle soft, inflated, ovoid or globose with numerous soft, spine-shaped processes
Back to 17 | Gomphocarpus |
| 19 | Leaves with (1 or) 2–25 minute raised glands in a cluster on upper surface of lamina at base of the midvein | 20 |
| Leaves without raised glands at base of the midvein
Back to 16 | 26 |
| 20 | Stems and lower surface of leaves densely and softly pubescent with long pale or rusty hairs, young shoots furry | 21 |
| Stems and leaves glabrous or finely pubescent with short pale hairs, young shoots not furry
Back to 19 | 22 |
| 21 | Hairs fawn or rusty; flowers more than 15 mm diam., in racemes on thick perennial peduncles | Thozetia |
| Hairs pale or colourless; flowers less than 5 mm diam., in axillary panicles; peduncles not persistent
Back to 20 | Marsdenia |
| 22 | Leaves very thick, fleshy but firm to rigid, faintly veined, broad-ovate to circular; corolla lobes valvate in bud; peduncles perennial, appearing as short thick spurs, with scars of flowers of earlier years | Hoya |
| Leaves thin or of moderate thickness, not rigid, mostly distinctly veined; corolla lobes contorted in bud; peduncles shed after flowering and fruiting
Back to 20 | 23 |
| 23 | Corona absent or segments adnate to lower part or base of the staminal column | 24 |
| Corona of 5 segments arising from the base of the corolla tube, free from column
Back to 22 | Araujia |
| 24 | Corona of 5 spreading fleshy obtuse knobs, fully fused to the column; pollinia globose, small, and laterally placed; flowers mostly purple to red (whitish in 1 species) | Tylophora |
| Corona absent or of 5–20 segments or lobes, not knob-like, each with a free upper part and a fused lower part; pollinia elongated, not round, erect or pendent, not laterally placed; flowers mostly whitish or yellow
Back to 23 | 25 |
| 25 | Corona absent or lower part of corona segments with a free wing or with basal auricles or lobes; pollinia erect | Marsdenia |
| Lower part of corona segments without a free wing or lobes or auricles, sometimes tubular at the base; pollinia pendent
Back to 24 | Cynanchum |
| 26 | Leaves lanceolate to ovate or oblanceolate or oblong, more than 5 mm wide; corona of 5 segments | 27 |
| Leaves linear, less than 5 mm wide; corona of 10 segments
Back to 19 | Rhyncharrhena |
| 27 | Leaves thin, soft, lanceolate to ovate, acute or acuminate at apex; pollinia erect, 4 per anther, 2 in each loculus; corona of 5 incurved horn-like segments shorter than column; flowers less than 5 mm diam., in many-flowered panicles | Secamone |
| Leaves thick, fleshy, firm to fairly stiff, mostly oblanceolate or oblong, apex abruptly pointed; pollinia pendent, 2 per anther, 1 in each loculus; corona of 5 erect segments with recurved tips, longer than column; flowers more than 10 mm diam., in few-flowered cymes
Back to 26 | Cynanchum |
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