Apocynaceae

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Apocynaceae
Apocynum cannabinum 5.jpg
Apocynum cannabinum
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Gentianales
Family: Apocynaceae
Juss.
Type genus
Apocynum
L.
Synonyms

Apocynaceae is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly called the dogbane family,[1] after the American plant known as dogbane, Apocynum cannabinum.[2] Members of the family are native to European, Asian, African, Australian, and American tropics or subtropics, with some temperate members.[1]

Many species are tall trees found in tropical rainforests, but some grow in tropical dry (xeric) 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.

Description[edit]

Alstonia scholaris, arrangement of leaves

Growth pattern[edit]

The dogbane family includes annual plants, perrenial herbs, stem succulents, woody shrubs, trees, or vines.[1][3] Most[citation needed] exude a milky sap with latex[citation needed], if injured.

Leaves and stems[edit]

Leaves are not divided into smaller leaflets (simple). Leaves may appear one at a time (singly) with each occurrence on alternating sides of the stem (alternate),[3] but usually[citation needed] occur in pairs or in whorls. When paired, they occur on opposite sides of the stem (opposite), with each pair occurring at an angle rotated 90° to the pair below it (decussate).

There is no stipule (a small leaf-like structure at the base of the leaf stem), or stipules are small and sometimes fingerlike.[3]

Inflorescence and fruit[edit]

Flowers are usually showy,[citation needed] have radial symmetry (actinomorphic), and are born in head that are cymes or racemes, but can rarely be fasciculate or solitary. They are perfect (bisexual), 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 is expanded at the apex into a massive clavuncle just below the stigma. 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.

Gallery[edit]

Taxonomy[edit]

As of 2012, the family was described as comprising some 5,100 species, where Apocynoideae, Asclepiadoideae, Periplocoideae, Rauvolfioideae, and Secamonoideae are its five subfamilies.[4][subscription required] The former family Asclepiadaceae is included in Apocynaceae according to the Angiosperm Phylogeny Group III (APG III) modern, largely molecular-based system of flowering plant taxonomy.[5] An updated classification, including 366 genera, 25 tribes and 49 subtribes, was published in 2014.[6]

Distribution and habitat[edit]

Species in this family are distributed mainly in tropical regions:

Ecology[edit]

Several genera are preferred larval host plants for the Queen Butterfly (Danaus gilippus).[7]

Toxicity[edit]

All plant-derived (i.e., phytochemical) natural products have some inherent toxicity on ingestion, and many are very toxic, even lethal. This is true of many contained in species of plants from the Apocynaceae family, which include several that are extremely poisonous if parts are ingested, or if they are not handled properly. Members containing cardiac glycosides—genera Acokanthera, Apocynum, Cerbera, Nerium, Thevetia, Strophanthus, etc.[citation needed]—have therapeutic ranges, but often are associated with accidental poisonings, in many cases lethal (see below). Alkaloid-producing species like Rauvolfia, Catharanthus, and Tabernathe are likewise the source of compounds with possible therapeutic ranges, but which have significant associated toxicities if not taken in appropriate doses and in controlled fashion.[citation needed]

Uses[edit]

Vinca major, a popular garden plant

Several plants of the Apocynaceae family members 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.[citation needed] Cardiac glycosides, which affect heart function, are a ready example.[citation needed] Members studied and known to have such glycosides include the Acokanthera, Apocynum, Cerbera, Nerium, Thevetia and Strophanthus.[citation needed] Rauvolfia serpentina (Indian snakeroot) synthesizes the alkaloids reserpine and rescinnamine, which are of interest in studies of the treatment of high blood pressure,[citation needed] as well as some forms of psychosis.[citation needed] Catharanthus roseus yields alkaloids studied with regard to the treatment of cancer.[citation needed] Certain species of the genus Tabernathe, most notably Tabernathe Iboga contain tryptamine alkaloids such as ibogaine in the roots.[citation needed]

Several genera are grown as ornamental plants, including Amsonia (bluestar), Nerium (oleander), Vinca (periwinkle), Carissa (Natal plum), Allamanda (golden trumpet), Plumeria (frangipani), Thevetia (lucky nut), Mandevilla (Savannah flower), and Adenium (desert-rose).[citation needed]

In addition, the genera Landolphia, Hancornia, Funtumia and Mascarenhasia were used as a commercial source of inferior rubber (see Congo rubber, made mostly from various Landolphia species harvested in the wild).[citation needed]

There may be reports of limited dietary uses of plants from this family,[clarification needed]—see however the section on toxicity above. The edible flower of Fernaldia pandurata (common name: loroco) is a popular part of El Salvadorian and Guatemalan cooking.[citation needed] Carissa (Natal plum) produces an edible fruit.[citation needed] The genus Apocynum was reportedly used as a source of fiber by Native Americans.[citation needed] The aromatic fruit juice from Saba comorensis (syn. Landolphia comorensis, the Bungo or Mbungo fruit) is a popular drink,[verification needed][citation needed] on Pemba Island and other parts of coastal Tanzania.[8]

Finally, ethnopharmacologic and ethnotoxicologic uses are also known. Ibogaine-type alkaloids from the roots of genus Tabernathe have been used in traditional African tribal ceremonies as a source of hallucinogens,[citation needed] and have been studied with regard to the treatment of drug addiction.[citation needed] The juice of Acokanthera species such as A. venenata and the milky juice of the Namibian Pachypodium have reportedly been used as venom for arrow tips by the San people,[citation needed] though others have reported that Pachypodium do not produce such milk.[9]

References[edit]

  1. ^ a b c Endress ME, Bruyns PV (2000). "A revised classification of the Apocynaceae s.l.". The Botanical Review 66 (1): 1–56. doi:10.1007/BF02857781. 
  2. ^ Heiser CB (2003). Weeds in my garden: observations on some misunderstood plants. Portland, Oregon: Timber Press. p. 50. ISBN 0-88192-562-4. 
  3. ^ a b c Apocynaceae, Thomas Rosatti, Jepson Herbarium
  4. ^ Nazia Nazar, David J. Goyder, James J. Clarkson, Tariq Mahmood and Mark W. Chase, 2013, "The taxonomy and systematics of Apocynaceae: Where we stand in 2012," Bot. J. Linnean Soc., 171(3, March), pp. 482–490, see [1], accessed 22 June 2015.[subscription required]
  5. ^ Angiosperm Phylogeny Group (2009). "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III". Bot. J. Linnean Soc. 161 (2): 105–121. doi:10.1111/j.1095-8339.2009.00996.x. 
  6. ^ Endress M.E., Liede-Schumann S. & Meve U. (2014). "An updated classification for Apocynaceae" (PDF). Phytotaxa 159: 175–194. doi:10.11646/phytotaxa.159.3.2. 
  7. ^ Klots, Alexander B. (1951). A Field Guide to the Butterflies of North America, East of the Great Plains. Cambridge, Massachusetts: The Riverside Press. pp. 77–79. 
  8. ^ "Saba comorensis in Agroforestree Database" (PDF). Retrieved 30 July 2012. 
  9. ^ Rapanarivo SHJV, Leeuwenberg AJM (1999). "Taxonomic revision of Pachypodium. Series of revisions of Apocynaceac XLVIII". In Rapanarivo SHJV. Pachypodium (Apocynaceae): taxonomy, habitats and cultivation. Balkema. pp. 1–82. ISBN 978-90-5410-485-8.