Adenia epigea Photo by: © Plantemania
Origin and Habitat: NE Madagascar (Plateaux de l'Ankarana).
Altitude range: Up to 100 metres above sea level.
Habitat and ecology: Adenia epigeaSN|33454]]SN|33454]] grows in dry forest on gneiss or volcanic rocks, at low altitude. They ae often found growing together with other ‘lumps’ such as Cyphostemma pachypusSN|33422]]SN|33422]] and Euphorbia ankaranensis. The other euphorbia frequently encountered in this area is Euphorbia pachypodioides.
Synonyms:
Description: Adenia epigea is is a slow growing large, deciduous, succulent liana up to 5 m long noted for the huge conical or rounded above-ground caudex it produces, and caudices often deformed and monstrous with diameters exceeding 1 m are well documented. What former have been known as "The Red Form" is actually Adenia firingalavensis var. stylosaSN|33454]]SN|28284]] which have been raised to its own species by David John Hearn in 2007: Adenia stylosaSN|28282]]SN|28282]].
Caudex: The swollen above-ground tuberous base of stem, also know as caudex, ranging in shape from round, globular, conical, flattened or irregular, semi-woody and often reaching up to one metre in diameter, abruptly narrowed at the top in a much-branched, cylindrical stems are 5–10 cm thick from which emerge, glabrous, deciduous vines (branches) up to 5 m long with tendrils 5-10 cm long. Without waxy coating either on the caudex or on the stem or its branches.
Leaves: Deeply 3-lobed, broadly ovate in outline, 2.5 5 cm long, 3-6 cm wide, margin entire. Medial lobe oval-triangular and obtuse at the apex, the laterals more acute. Petiole 1.5-7 cm long longer than the leaf-blade, without glands, the two glands being carried by the thickened anterior border of the blade. Tendrils simple, axillar usually associated with the inflorescence.
Inflorescence (small cymes): Usually on the upper third of the vines, male infloersceces each bearing 2- to 5-flowers, female inflorescences reduced to 1-2 flowers. Bracts reddish, small, narrow and deciduous. Rudimentary leaves small, reduced to a short petiole, with 2 glands and a rudiment of limb, inserted at the base of the tendrils-inflorescences. Tendril 2-4.5 cm long. Peduncle 4-7 cm long. Pedicels, 5,5-6 mm long.
Male flowers: Receptacle tubular to narrowly funnel-shaped, including stipe 25-28 mm long. Calix tube absent. Sepals lanceolate 8-10 mm long. Petal white oblong, obtuse, 6-7 mm long. Filaments free at the top for over 1 mm, united to the receptacle tube along its entire length. Anthers 7 mm long. Corona of minute fleshy appendages. Nectar-glands absent.
Female flowers: 11-15 mm long on very short pedicel (1-2 mm). Tubular receptacle, very short (3 mm.) Sepals 7 mm long, petals as long, white. Ovary ovoid-oblong, 3 -3.5 mm long. Styles united for c. 4 mm, subglobose, woolly, each 1 mm in diameter.
Fruit: Solitary, elongated elongate fusiform (attenuated towards the two extremities), about 13 cm long and 3 cm in diameter. Pericarp (skin) thinly coriaceous, smooth.
Seeds: About 50 per fruit, suborbicular, 5-6 x 4-5 mm strongly bordered..
Related species. Adenia epigeaSN|28284]]SN|33454]] is close to Adenia monadelpha but distinct by the long slender fruit.
Bibliography: Major references and further lectures
1) H.Humbert “Flore de Madagascar et des Comorres” 143th family – Passifloraceae, by H. Perrier de la Bathie 1945
2) Urs Eggli “Illustrated Handbook of Succulent Plants: Dicotyledons” Springer Science & Business Media, 2002
3) Adenia epigea in: Cactus and Succulent Journal - Volume 79, 2007
4) Bihrmann's caudiciforms “Adenia epigea” web <http://www.bihrmann.com/caudiciforms/subs/ade-epi-sub.asp>
5) Hilary Bradt, Daniel Austin “Madagascar” Bradt Travel Guides, 01 July 2014
6) Adenia epigea in: Adansonia, Volume 10 Muséum National d'Histoire Naturelle, Laboratoire de phanérogamie, 1970
7) Al Laius “Like it or lump it Madagascan caudiciforms” Essex Succulent Review Volume 53 Number 3 September 2016
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