Origin and Habitat: Central and south-west Madagascar.
Altitude range: From sea level to about 500 metres.
Habitat and ecology: Forest and semi-arid forest woodlands often on sandstone rocks, in full exposure or among bushes. Accompanied by Pachypodium graciliusSN|14792]]SN|14792]], Ceropegia dimorpha, Aloe contigua, Aloe isaloensis, Aloe deltoideodontavar. brevifolia and Euphorbia miliiSN|23360]]SN|23360]].

• Cynanchum marnierianum Rauh

Description: Cynanchum marnierianumSN|30357]]SN|30357]] is a bushy sprawling stem-succulent with many, dark green or purplish leafless branches, covered by irregular tubercles and minute hairs. Looks and feels like rubbery, grey sticks and in the autumn, bright yellowish green lanternlike flowers sprout out of the entire length of each stem. Flowers, being five greenish-brown petals uniting at the tips are reminiscent of Ceropegia. Once the flowers start to fade, the little arms withdraw and look like little octopi.
Leaves: At internodes, to 1.5 mm long, soon falling.
Stem: Succulent, ong, thin, flexible, dark purplish green, weak, 5-7 mm thick. that are curiously tend randomly pustulate, covered in fine white hairs, with a milky sap. New branches are green and they get purplish brown as the grow. In habitat, the stems grow to several metres in length. In cultivation, up to 2.5 m or more.
Flowers: 1-6 together on stalk 3-6 mm long. Corolla-lobes 5, yellow. 5-8 mm, linear, initially united on the tips forming a sphere. Corona white, tubular, 1.5-2 mm tall. Finely toothed at the top.
Blooming season: Autumn.

Bibliography: Major references and further lectures
1) Werner Rauh, Herman Schwartz “Succulent and xerophytic plants of Madagascar” Volume 2 Strawberry Press, 1998
2) Clive Innes “Complete Handbook of Cacti and Succulents” Van Nostrand Reinhold Company, 01 December 1981
3) Focke Albers, Ulrich Meve “Illustrated Handbook of Succulent Plants: Asclepiadaceae: Asclepiadaceae” Volume 4 Springer, 2002
4) Rauh. “Succulent & xerophytic plants of Madagascar” 2: 253-5 1998
5) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11 August 2011

Cultivation and Propagation: Cynanchum marnierianum is an interesting Asclepiad that it not seen in many collections as yet. Perfect for a very unusual hanging basket. The stems are long, long, l olive green ropes with a warty texture. Very easy to grow, it fills out a basket rapidly if the stems are pruned and poked back into the pot to root and start growing. Give the plant a fairly rich but well-drained compost which consists of non organic material such us clay, pumice, lava grit, and peat or leaf-mould. Water regularly during the active growing season from March to September. No water should ever be allowed to stand around the roots. Keep almost completely dry in winter. It is a relatively fast growing and long lived plant and once established, it will be content in its position and with its soil for years.
Fertilization: Need a perfect fertilizer diet in summer. Use preferably a cacti and succulents fertilizer with high potassium content including all micro nutrients and trace elements or slow release fertilizer.
Exposure: This plant has an excellent heat tolerance, and need full sun to light shade exposures, but can tolerate shade. However shade grown plants will tend to produce fewer, and etiolated growth. The colour of this plant is much more marked if grown in full sun. But if it is possible to keep the growth of this species compact, with denser, shorter stems such plants can be outright attractive.
Watering: Water regularly during the active growing season. No water should ever be allowed to stand around the roots. Keep almost completely dry in winter. Care must be given in watering, keeping them warm and wet while growing, and cooler and dry when dormant.
Hardiness: Some cold tolerance, however it can be difficult to get it to look its best without a good amount of heat and sun and so it is only really suited to the tropics (USDA Zones 9-12). It can be grown outdoors in the summer months to benefit from direct exposure to light, and especially exposure to high summer temperatures. Protection in a warm greenhouse in the middle of the winter will greatly increase the survival rate.
Disease and pests: The aphid occasionally feeds on young stems. The plant are also attractive to mealy bugs.
Rot: Rot it is only a minor problem with Cynanchum if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much. It is very unlikely to lose this plant from root rot from excessive water.
Maintenance: Re-pot every two-three years. It like quite small pots, repot in early spring. It can be pruned for shape and branching and trim off the dead 'arms'.
Known hazards: As mentioned above, all parts of the plant exude a milky latex when damaged. Contact with the latex should be avoided.
Propagation: This species is very easy to propagate. Cuttings root quickly both in soil and in water. Cuttings are relatively easy in a 1:1:1 mixture of pumice, vermiculite and potting soil, at c. 27°C. If you remove an offset, remember to let it dry for some days, letting the wound heal (cuttings planted too soon easily rot before they can grow roots). Lay it on the soil and insert the stem end partially into the substrate. Try to keep the cutting somewhat upright so that the roots are able to grow downward. It is better to wash the cut to remove the latex. The newly planted stems take a few weeks to establish, and then start growing. The best time to strike cuttings is spring.
It is also possible to propagate by seeds. The seed will loose viability in storage, and may not be viable the following year, so the seed should be planted as soon after harvesting as possible. Use a well-drained sowing medium of sandy loam with very well-rotted compost, and preferably sieved river sand to cover the seed. The ideal size of the sand grains should be 1 mm. Germination usually occurs within about a week or two.