Apocynaceae


Apocynaceae is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison. Members of the family are native to the European, Asian, African, Australian, and American tropics or subtropics, with some temperate members. The former family Asclepiadaceae is considered a subfamily of Apocynaceae and contains 348 genera. A list of Apocynaceae genera may be found here.
Many species are tall trees found in tropical forests, but some grow in tropical dry environments. Also perennial herbs from temperate zones occur. Many of these plants have milky latex, and many species are poisonous if ingested. Some genera of Apocynaceae, such as Adenium, have milky latex apart from their sap, and others, such as Pachypodium, have clear sap and no latex.

Gallery

Taxonomy

As of 2012, the family was described as comprising some 5,100 species, in five subfamilies:
The former family Asclepiadaceae is included in Apocynaceae according to the Angiosperm Phylogeny Group III modern, largely molecular-based system of flowering plant taxonomy.
An updated classification, including 366 genera, 25 tribes and 49 subtribes, was published in 2014.

Distribution and habitat

Species in this family are distributed mainly in tropical regions:

Growth pattern

The dogbane/milkweed family includes annual plants, perennial herbs, stem succulents, woody shrubs, trees, or vines. Most exude a milky sap with latex, if injured.

Leaves and stems

are. Leaves may appear one at a time with each occurrence on alternating sides of the stem, but usually occur in pairs. When paired, they occur on opposite sides of the stem, with each pair occurring at an angle rotated 90° to the pair below it.
There is no stipule, or stipules are small and sometimes fingerlike.

Inflorescence and fruit

s have radial symmetry, and are borne in heads that are cymes or racemes, or are solitary in axils. They are perfect, with a synsepalous, five-lobed calyx united into a tube at the base. Inflorescences are terminal or axillary. Five petals are united into a tube with four or five epipetalous stamens. The style head is swollen. The pollen is transported in foam. The ovary is usually superior, bicarpellary, and apocarpous, with a common fused style and stigma.
The fruit is a drupe, a berry, a capsule, or a follicle. The seeds are often winged or have appendages of long silky hairs.

Ecology

Several genera are preferred larval host plants for the Queen Butterfly.

Toxicity

Many species of plants from the family Apocynaceae have some toxicity, with some being extremely poisonous if parts are ingested, or if they are not handled properly. Genera containing cardiac glycosides— Cerbera, Nerium, Cascabela, Strophanthus, Acokanthera, Apocynum, Thevetia, etc.—have therapeutic ranges, but are often associated with accidental poisonings, in many cases lethal. Alkaloid-producing species like Rauvolfia serpentina, Catharanthus roseus, and Tabernanthe iboga are likewise the source of compounds with therapeutic ranges, but which have significant associated toxicities if not taken in appropriate doses and in controlled fashion.

Uses

Several members of the family Apocynaceae have had economic uses in the past. Several are sources of important natural products—pharmacologic tool compounds and drug research candidates, and in some cases actual prescription drugs. Cardiac glycosides, which affect heart function, are a ready example. Members studied and known to have such glycosides include the Acokanthera, Apocynum, Cerbera, Nerium, Thevetia and Strophanthus. Rauvolfia serpentina contains the alkaloid reserpine, which has been used as an antihypertensive and an antipsychotic drug but its adverse effects limit its clinical use. Catharanthus roseus yields alkaloids used in the treatment of cancer. Tabernanthe iboga, Voacanga africana, and Tabernaemontana undulata contain the alkaloid ibogaine, which is a psychedelic drug which may help with drug addiction, but which has significant adverse effects, with ibogaine being both cardiotoxic and neurotoxic. Ajmalicine, an alkaloid found in Rauvolfia spp., Catharanthus roseus, and Mitragyna speciosa, is an antihypertensive drug used in the treatment of high blood pressure.
Several genera are grown as ornamental plants, including Amsonia, Nerium, Vinca, Carissa, Allamanda, Plumeria, Thevetia, Mandevilla, and Adenium.
In addition, the genera Landolphia, Carpodinus,and Mascarenhasia have been used as commercial sources of inferior rubber..
There are limited dietary uses of plants from this family. The flower of Fernaldia pandurata is edible. Carissa produces an edible fruit, but all other parts of the plant are poisonous. The genus Apocynum was reportedly used as a source of fiber by Native Americans. The aromatic fruit juice from Saba comorensis is used as a drink.
Finally, ethnopharmacologic and ethnotoxicologic uses are also known. Ibogaine-type alkaloids from the roots of genus Tabernathe have traditionally been used by Africans ceremonially as hallucinogens, and have been studied with regard to the treatment of drug addiction. The juice of Acokanthera species such as A. venenata and the milky juice of the Namibian Pachypodium have been used as poison for arrow tips.