About Apocynaceae
Apocynaceae, the dogbane family, is a family of eudicots placed in the order Gentianales under APG IV, with roughly 380 to 390 genera and more than 5,000 species. It is distributed worldwide, mainly in tropical to warm temperate regions. Most species exude a milky latex when cut, and the leaves are usually simple and opposite. Many members contain alkaloids or cardiac glycosides and are poisonous, so plants such as oleander (Nerium) should be handled with care. Growth forms range from trees and shrubs to lianas and succulents with swollen stems. In horticulture the family includes the caudiciform succulents Pachypodium and Adenium, as well as Plumeria and Hoya. Under APG the former milkweed family Asclepiadaceae is included in Apocynaceae.
Pachypodium is a genus of the dogbane family with about 25 species, 20 of them endemic to Madagascar and the rest in southern Africa. They grow in arid habitats with long dry seasons and are recognized by swollen, water-storing stems, spines in pairs or triplets, and leaves shed in the dry season. Habits range from low, flattened caudex plants to trees over 5 m tall, with white or yellow flowers. In horticulture P. lamerei, P. rosulatum subsp. gracilius and P. brevicaule are grown as caudiciform succulents. The whole genus is listed in CITES Appendix II, and four species, P. ambongense, P. baronii, P. decaryi and P. windsorii, are listed in Appendix I.
Hoya is a genus of roughly 350 to 500 species of climbing plants in the subfamily Asclepiadoideae of Apocynaceae. It ranges from India and southern China through Southeast Asia to Australia and the Pacific islands, and also occurs in southern Kyushu and the Ryukyu Islands of Japan. Most species are epiphytic or rock-dwelling vines that climb by aerial roots and have fleshy leaves. Their star-shaped, waxy flowers are borne in rounded umbel-like clusters on persistent flower stalks that bloom again in later years, a trait that distinguishes the genus. Species in cultivation include Hoya carnosa and Hoya kerrii, and the genus was formerly placed in Asclepiadaceae.
Adenium is a genus of the dogbane family native to Africa, from the Sahel to southern Africa, and the Arabian Peninsula. The number of species is debated, from a single variable species to around twelve. The plants have a swollen, caudex-like stem base and red or pink tubular flowers, and the sap contains cardiac glycosides and is poisonous. Adenium obesum, the desert rose, is widely grown as a caudiciform succulent, and the thick-stemmed A. arabicum is also in cultivation.
Scientific Name
Apocynaceae