Adenia

Primary tabs

Adenia

Description

Unarmed climbers (in Mal.), often with tubers. Leaves (in Mal.) simple, entire or lobed, pinni- or palminerved; Stipules (in Mal.) minute. Inflorescences mostly stalked, few- to many-flowered, often with l(-3) tendrils, rarely collected into raceme-like short-shoots. Flowers unisexual (plants mostly dioecious), in ♂ with vestigial ovary, in ♀ the stamens reduced to ± subulate staminodes (rarely bisexual in Afr.), mostly greenish to yellowish; Sepals (4-)5(-6), free or partially connate into a calyx tube. Petals (4-)5(-6), free or partially connate with the calyx tube, greenish, creamy, or white, mostly smaller than the sepals. Stamens 5, (in Mal.) inserted at the base of the hypanthium, free or partially connate into a filamental tube, the tube often connected with the hypanthium by septa opposite the petals; Ovary subsessile, globose to fusiform; Capsule 3-valved, (in Mal.) coriaceous or woody.

Distribution

Africa: present Asia-Tropical: Madagascar: present present N. & NE. Australia: present Pacific: present SE. Asia: present Solomon Is: present ttropical and subropical Africa: present
About 92 spp. in 6 sections in ttropical and subropical Africa (c. 60 spp.), Madagascar (c. 20 spp.) and SE. Asia, Malesia, and N. & NE. Australia, in the Pacific east to the Solomon Is. (A. heterophylla). Especially in Africa and Madagascar quite a number of local endemics.

Morphology

& Taxon. In most species the filaments are in the basal part united into a (short) tube, whereas this tube is connected by septa with the hypanthium, opposite the petals. In some members of sect. Microblepharis and sect. Blepharanthes the thus formed apartments are ± bulging, forming a 5-saccate hypanthium in which the 5 disk glands are situated.
As pointed out in my monograph (), 6 sections are recognized, mainly based on the flower structure, and sustained by characters found in the position of the glands on the leaves. In many species the sepals (and often also the petals) are partially connate into a tube; and this condition is considered as an advanced state against free sepals.
The Indo-Malesian species belong to 3 sections: (i) sect. Microblepharis (Africa, Madagascar, SE. Asia; A. penangiana in Malesia), (ii) sect. Blepharanthes (Africa, SE. Asia; not in Malesia), and (iii) sect. Erythrocarpus (most Malesian spp.). Sect. Microblepharis, with free sepals and petals, is considered as primitive; sect. Erythrocarpus as relatively derived because of the tubiform flowers with partially connate sepals and petals, the absence of the corona, and the basal blade-glands situated on auricles at the top of the petiole.
As to the leaf glands 3 types are distinguished: (i) glands at blade-base 2, or by connation (reduction) 1, sessile at the very blade-base, or on auricles at the transition of blade and petiole or at the top of the petiole; (ii) blade-glands on the lower surface of the blade scattered or in ± fixed places; in lobed leaves often corresponding with the sinusses between the lobes; (iii) marginal glands, mostly very small, at the end of a small vein, in some species on teeth.
In all Indo-Malesian species the fruits are red, and the funicles of the seeds are longer than in all other African or Madagascan species.
Heteroblasty and heterophylly. As in many lianas the leaves of most Adenias are very variable, and in many species lobed as well as entire leaves are found. Also in juvenile forms the leaves may be quite different in shape and in presence or position of the glands, as compared with the adult stage. In adult A. cordifolia, for instance, the basal glands of the cordate, ovate leaves are situated in two distinct, separate, hollowed auricles lateral at the top of the petiole, whereas in the juvenile stage these auricles are absent, and the blade of a peculiar lunate- or 3-lobed shape with mostly peltate base, with or without 1-2 very small glands.

Citation

BENTH. & HOOK.f. - in Gen. Pl. 1867: 813
HARMS - in E. & P., Nat. Pfl. Fam. 3. 1893: 83
FORSK. - in Nat. Pfl. Fam., ed. 2. 1925: 488
LAMK - in Encycl. Meth. Bot. 1797: 208
HALL.f. - in Med. Rijksherb. 1922: 8
CHAKRAVARTY - in Bull. Bot. Soc. Beng. 1951: 68
ENGL. - in Bot. Jahrb. 1891: 374
DC. - in Prod. 1828: 336
HUTCH. - in Gen. Fl. Pl. 1967: 373
DE WILDE - in Thesis, Med. Landb. Hogeschool Wagen. 1971