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Origin and Habitat: Kenya (Kibwezi, Teita, Mackinnon Districts), Tanzania (Kilimanjaro, Lushoto , Sindeni [Zindeni], Uzaramo Districts and Zanzibar) and somalia. Estimated area of occupancy (AOO) - km2:159.7. The number of locations is more than 10. Fragmentation is not a factor for this species.
Altitude range: 0–1000 metres above sea level.
Habitat and Ecology: Adenia keramanthus is a succulent herb with climbing branches of dry rock slopes, scattered tree grassland, open wooded grassland, open bushland and dry forest margins. Threats to these habitats can be burning, cattle grazing, cutting of cover and over-use of land; but this taxon is both poisonous (and will therefore be eaten less) and fire-resistant. In some localities small-scale farming and shifting cultivation are impacting, but in such situations this species might survive. It grows together several succulent plants, including, Adenium obesum, Aloe secundiflora, Cissus cactiformis, Euphorbia atroflora, Euphorbia subscandens, and portulacas.
Description: Adenia keramanthus is a sparingly branched succulent herb or shrub from a tuberous rootstock (pachycaul). It is a quick growing plant that can reach up to 50-100 cm in height. It branches freely on the upper third and can bloom when only 15-20 cm tall. The flower is a cream-colored cup, facing downward, and producing a single seed pod. The flowers are often produced before the leaves are fully developed. The fruits, about the size of an egg, are bright red. This species is an exception in the genus because of the covering of fine grey or rusty brown hairs on the trunk and leaves. The general habit is that of a succulent, few-stemmed shrub rather than the vining form of many other species.
Derivation of specific name: keramanthus Greek, 'keramion', pot; and Greek. 'anthos', flower; for the broadly tubular, urceolate, pot-like flowers.
Rootstock: Tuberous, grey-barked up to 10 cm thick typical knotty and tomentose.
Stems: Succulent stems to up to 1 m long, pubescent with rusty brown hairs. Tendrils absent.
Leaves: Pale green, with a grey felt-like covering on both sides, ovate to orbicular in outline, not lobed, truncate to cordate at the base, top subacute to rounded, 1.5–15 cm long, 5-nerved from the base. Margin subentire or up to 5 mm. Toothed, sometimes punctate near the margin beneath. Petiole 1–12 cm. Stipules linear, sometimes deeply and irregularly cut, 3–10 mm long, pubescent.
Inflorescences: Sessile, up to 10-flowered in male plants, 1–2-flowered in female plants, without tendrils.
Male flowers: Urceolate (urn-shaped), 17–26 mm long including the stipe, 8–10 mm wide. Hypanthium cup-shaped including calyx-tube 10–19 mm long. Sepals 3–5 mm long, with woolly fringed edge. Petals lanceolate to linear, 5–7 mm long, fringed, inserted in calyx-tube. Filaments 3–5 mm long, fused at base for 1.5 mm. Anthers 6–7 mm long, obtuse. Corona consisting of a few hairs or absent.
Female flowers: Urn-shaped resembling male flowers, 18–22 mm long. Pistil 7–9 mm long on short gynophore (stalk which supports the gynoecium elevating it above other floral parts). Styles united for c. 3 mm.
Fruits: Subglobose1 per inflorescence, on short gynophore, 3.5–5 cm long, 3–4.5 cm in diameter, leathery, sometimes spongy inside, crimson or purplish when fresh.
Seeds: 20–40 per capsule, broadly ovoid to ellipsoid, 7(–9) mm long.
Bibliography: Major references and further lectures
1) Werner Rauh “The Wonderful World of Succulents: Cultivation and Description of Selected Succulent Plants Other Than Cacti” Smithsonian Institution Press, 1984
2) W. J. J. O. de Wildem “Flora of Tropical East Africa”, 1975
3) M. Thulin [updated by M. Thulin 2008] “Flora Somalia”, Vol 1, 1993
4) “Medicinal Plants”, Volume 1 PROTA, 2008
5) Umberto Quattrocchi “CRC World Dictionary of Medicinal and Poisonous Plants: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology” (5 Volume Set) CRC Press, 19 April 2016
6) “The Euphorbia journal” Strawberry Press, 1991
7) Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer Science & Business Media, 29 June 2013
8) Cal Eichler, “Adenia keramanthus Family: Passifloraceae” SACXS FACTS, Newsletter for the San Antonio Cactus and Xerophyte Society August 2010 Volume 22, Number 8, p. 8.
9) C. Glass and R. Foster “Adenias (The succulent passion flowers)”, July Meetings, Saturday, July 11, 1987 1:30 p.m. Casa del Prado, Room 101, Balboa Park, Program: Succulents of namaqualand Espinas y Flores Newsletter of the San Diego Cactus and Succulent Society, Inc. Affiliated with the Cactus and Succulent Society of America Volume XXII, Number 7, July 11, 1987
10) IUCN SSC East African Plants Red List Authority. 2013. Adenia keramanthus. The IUCN Red List of Threatened Species 2013: e.T179889A1593408. http://dx.doi.org/10.2305/IUCN.UK.2013-2.RLTS.T179889A1593408.en. Downloaded on 27 January 2017.
Cultivation and Propagation: Still rare in cultivation, Adenia keramanthus is an excellent pot plant and it should make an interesting addition to a collection. Grow A. keramanthus in full sun, but protect from temperatures below 10° C in the winter.
Growth rate: It grows well and it is possible to increase the speed of growth to some extent by providing adequate amount of water, warmth, and fertilizer during the active growing season, but it’s susceptible to rotting if too wet.
Exposure: It needs full sun or light shade. Avoid direct blasting sun in summer. Bright light if grown indoors.
Soil: It needs a very porous potting medium (add pumice, vulcanite, and perlite). It does better in a rather acidic soil.
Waterings: Since it photosynthesizes on both leaves and stems, uniform watering is required for best growth and performance .Water frequently while plant is in full growth, but keep dry during the winter after the branches have died back. It rot easily and do NOT like a lot of water when it has no leaves.
Fertilizer: Benefits from moderate doses of a well-balanced, slow-release fertilizer.
Frost tolerance: Due to its African origin keep warm in winter, the minimum safe average temperature is 15°C, although it can go lower for short periods. It can be grown outdoors in frost-free climates, need anyway to kept above 10°C and dry in winter. It is very prone to rot in cool, wet conditions. USDA Zone 12, but does very well in containers.
Maintenance: Repot every two years. It like pots with generous drain holes. It may be trained to desired shape and size by pruning side branches. Raising the base slightly over a period of time will enable the caudex to emerge and swell.
Propagation: The species can be propagated by both seeds and cuttings. Harvest seeds after pods ripen and dry out. Cuttings from this plant will root easily. The plants for seed production are generally grown from cuttings since these bloom more freely. The plants for decoration are grown from seed since they develop a caudex.
Traditional uses: Leaves and roots are reported as a snake-bite treatment.
Warning: As with all Adenias, all parts of this plant are very toxic, and they should be handled with caution, particularly when pruning.
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