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The Family Apocynaceae or dogbane family of flowering plants includes trees, shrubs, herbs, or lianas. Many species are tall trees found in the tropical rainforest, and most are from the tropics and subtropics. There are also some perennial herbs from temperate zones. These plants have milky sap and many species are poisonous if ingested.

Taxonomy

The family, as currently recognized, includes some 1500 species divided in about 424 genera. The family Asclepiadaceae is now included in the Apocynaceae (Endress & Bruyn, 2000)

There are five subfamilies:

• Rauvolfioideae
• Apocynoideae
• Periplocoideae
• Secamonoideae
• Asclepiadoideae

The last three subfamilies used to belong to the Asclepiadaceae.

Distribution

Species in this family are distributed mainly in tropical regions:

• In the rainforests and swamps of India and Malaya: small to very tall evergreen trees, often with buttress roots, such as Alstonia and Dyer.
• In northern Australia: small evergreen trees such as Cerbera and Ochrosia .
• In deciduous forests of Africa and India: smaller trees such as Carissa , Wrightia and Holarrhena .
• In tropical America, India, Myanmar and Malaya: evergreen trees and shrubs, such as Rauwolfia , Tabernaemontana and Acokanthera .
• In Central America: Plumeria, or the frangipani, with its waxy white or pink flowers and a sweet scent.
• In South America, Africa and Madagascar: many lianas such as Landolphia .
• In the Mediterranean region: Nerium, with the well-known oleander or Be-still tree (Nerium oleander).
• The only genera found in temperate Europe away from the Mediterranean are Vinca (Apocynoideae) and Vincetoxicum (Asclepiadoideae).
• In North America: Apocynum, dog bane or Indian hemp, including Apocynum cannabinum, a traditional source of fiber.

Characteristics

The leaves are simple, usually opposite and decussate, or whorled; lacking stipules. Flowers are usually showy, radially symmetrical (actinomorphic), aggregated in cymose or racemose inflorescences (rarely fasciculate or solitary). They are perfect (bisexual), with a synsepalous, 5-lobed calyx. Inflorescences are terminal or axillary. The stamens are inserted on the inside of the corolla tube. The ovary is usually superior.

The fruit is a drupe, a berry, a capsule or a follicle.

Genera

Apocynoideae

The following genera used to belong to the family Asclepiadaceae :

• Araujia
• Asclepias (subfamily Asclepiadoideae)
• Caralluma
• Ceropegia
• Cionura
• Cynanchum
• Periploca (Subfamily Periplocoideae)
• Vincetoxicum

Uses

Several plants of this family had economic uses in the past.

The genera Carpodinus , Landolphia , Hancornia , Funtumia and Mascarenhasia were an inferior commercial source of rubber.

The juice of Acokanthera species such as A. venenata and the milky juice of the Namibian Pachypodium has been used as venom for arrow tips by the Bushmen.

The following genera are ornamental plants: Amsonia (bluestar), Nerium (oleander), Vinca (periwinkle), Carissa (Natal plum, an edible fruit), Allamanda (golden trumpet), Plumeria (frangipani), Thevetia (lucky nut), Mandevilla (Savannah flower).

Rauvolfia cafra is the Quinine tree. Rauvolfia serpentina or Indian Snakeroot yields the alkaloids reserpine and rescinnamine .

Some are sources of drugs, such as cardiac glycosides, affecting the heart function: Acokanthera , Apocynum, Cerbera, Nerium, Thevetia and Strophantus .

The genus Apocynum was used as a source of fiber by Native Americans.

Reference

• Endress and Bruyn. 2000. A revised classification of the Apocynaceae. The Botanical Review, 66: 1-56

External link

• Entry from The Families of Flowering Plants