''Alstonia'' is a widespread

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

trees and shrubs, of the family

Apocynaceae Apocynaceae (, from '' Apocynum'', Greek for "dog-away") 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. Notable mem ...

. It was named by

Robert Brown Robert Brown may refer to: Robert Brown (born 1965), British Director, Animator and author Entertainers and artists * Washboard Sam or Robert Brown (1910–1966), American musician and singer * Robert W. Brown (1917–2009), American printmaker ...

in 1811, after Charles Alston (1685–1760), professor of botany at

Edinburgh Edinburgh is the capital city of Scotland and one of its 32 Council areas of Scotland, council areas. The city is located in southeast Scotland and is bounded to the north by the Firth of Forth and to the south by the Pentland Hills. Edinburgh ...

from 1716 to 1760. The type species ''Alstonia scholaris'' (L.) R.Br. was originally named ''Echites scholaris'' by

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

in 1767.

Description

''Alstonia'' consists of about 40–60

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

(according to different authors) native to tropical and subtropical Africa, Central America, Southeast Asia, Polynesia and Australia, with most species in the Malesian region. These trees can grow very large, such as ''Alstonia pneumatophora'', recorded with a height of 60 m and a diameter of more than 2 m. ''Alstonia longifolia'' is the only species growing in Central America (mainly shrubs, but also trees 20 m high). The leathery, sessile, simple leaves are elliptical, ovate, linear or lanceolate and wedge-shaped at the base. The leaf blade is dorsiventral, medium-sized to large and disposed oppositely or in a whorl and with entire margin. The leaf venation is pinnate, with numerous veins ending in a marginal vein. Phyllotaxy is whorled i.e. two or more leaves arises at a node and form a whorl . The

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

is terminal or axillary, consisting of thyrsiform cymes or compound umbels. The small, more or less fragrant flowers are white, yellow, pink or green and funnel-shaped, growing on a pedicel and subtended by

bract In botany, a bract is a modified or specialized leaf, associated with a reproductive structure such as a flower, inflorescence axis or cone scale. Bracts are usually different from foliage leaves in size, color, shape or texture. They also lo ...

s. They consist of 5 petals and 5

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 Etymology The term ''sepalum'' ...

s, arranged in four whorls. The fertile flowers are hermaphrodite. The gamosepalous green sepals consist of ovate lobes, and are distributed in one whorl. The annular disk is hypogynous. The five gamesepalous petals have oblong or ovate lobes and are disposed in one whorl. The corolla lobes overlapping to the left (such as ''A. rostrata'') or to the right (such as ''A. macrophylla'') in the bud. The

ovary The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/ oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are end ...

has 2 separate follicles with glabrous or ciliate, oblong seeds that develop into deep blue podlike, schizocarp

fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...

, between 7–40 cm long. The plants contain a milky latex, rich in poisonous

alkaloid Alkaloids are a broad class of natural product, naturally occurring organic compounds that contain at least one nitrogen atom. Some synthetic compounds of similar structure may also be termed alkaloids. Alkaloids are produced by a large varie ...

s. Fijians use the latex of ''A. costata'' (''saurua'', ''sorua'') as a form of chewing gum. The ''Alstonia macrophylla'' is commonly known in Sri Lanka as 'Havari nuga' or the 'wig banyan' because of its distinct flower that looks like a woman's long wig. ''Alstonia'' trees are used in traditional medicine. Many ''Alstonia'' species are harvested for timber, called ''pule'' or ''pulai'' in Indonesia and Malaysia. Trees from the section ''Alstonia'' produce lightweight timber, while those from the sections ''Monuraspermum'' and ''Dissuraspermum'' produce heavy timber. ''Alstonia'' trees are widespread and mostly not endangered. However a few species are very rare, such as ''A. annamensis'', ''A. beatricis'', ''A. breviloba'', ''A. stenophylla'' and ''A. guangxiensis''.

Species

''Alstonia'' has five distinct sections, each a

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

group; ''Alstonia'', ''Blaberopus'', ''Tonduzia'', ''Monuraspermum'', ''Dissuraspermum''. ,

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

accepts the following 44 species: *'' Alstonia actinophylla'' (A.Cunn.) K.Schum. – milkwood - New Guinea, N Australia *'' Alstonia angustifolia'' A.DC. - Borneo, W Malaysia, Sumatra *'' Alstonia angustiloba'' Miq. - Borneo, W Malaysia, Sumatra, Thailand, Java *'' Alstonia annamensis'' (Monach.) K.Sidiyasa - Cambodia, Vietnam *'' Alstonia balansae'' Guillaumin - New Caledonia *'' Alstonia beatricis'' K.Sidiyasa - Waigeo I in E Indonesia *'' Alstonia boonei'' De Wild. - W + C + E Africa *'' Alstonia boulindaensis'' Boiteau - New Caledonia *'' Alstonia breviloba'' K.Sidiyasa - Papua New Guinea *'' Alstonia congensis'' Engl. - W + C Africa *'' Alstonia constricta'' F.Muell. – bitterbark, quinine tree, Australian fever bark - E Australia *'' Alstonia coriacea'' Pancher & S.Moore - New Caledonia *'' Alstonia costata'' R.Br. - S Pacific *'' Alstonia curtisii'' King & Gamble - Thailand *'' Alstonia deplanchei'' Van Heurck & Müll.Arg. - New Caledonia *'' Alstonia guangxiensis'' D.Fang & X.X.Chen - Guangxi in China *'' Alstonia iwahigensis'' Elmer - Borneo, Palawan *'' Alstonia lanceolata'' Van Heurck & Müll.Arg. - New Caledonia *'' Alstonia lanceolifera'' S.Moore - New Caledonia *'' Alstonia legouixiae'' Van Heurck & Müll.Arg. - New Caledonia *'' Alstonia lenormandii'' Van Heurck & Müll.Arg. - New Caledonia *'' Alstonia longifolia'' (A.DC.) Pichon - Mexico, Central America *'' Alstonia macrophylla'' Wall. ex G.Don – batino, devil tree - S China, Sri Lanka, SE Asia, New Guinea *'' Alstonia mairei'' H. Léveillé - S China, N Vietnam *'' Alstonia muelleriana'' Domin – jackapple, leatherjacket, milky yellowwood - New Guinea, Queensland *'' Alstonia neriifolia'' D.Don - Nepal, Sikkim, Bhutan *'' Alstonia odontophora'' Boiteau - New Caledonia *'' Alstonia parkinsonii'' (M.Gangop. & Chakrab.) Lakra & Chakrab. - Andaman Is. *'' Alstonia parvifolia'' Merr. - Philippines *'' Alstonia penangiana'' K.Sidiyasa - Penang Hill in Malaysia *'' Alstonia pneumatophora'' Backer ex L.G.Den Berger - W Malaysia, Borneo, Sulawesi, Sumatra *'' Alstonia quaternata'' Van Heurck & Müll.Arg. - New Caledonia *'' Alstonia rostrata'' C.E.C.Fischer - Yunnan, Indochina, W Malaysia, Sumatra *'' Alstonia rubiginosa'' K.Sidiyasa - Papua New Guinea *'' Alstonia rupestris'' Kerr - Thailand *'' Alstonia scholaris'' (L.) R.Br. – pali-mari, dita bark, bitter bark, milkwood, milky bean, milky pine, white cheesewood, scholar tree, blackboard tree - E + S + SE Asia, Papuasia, N Australia *'' Alstonia sebusii'' (Van Heurck & Müll.Arg.) Monach. - Yunnan, Bhutan, Assam, N Myanmar *'' Alstonia spatulata'' Blume – hard milkwood, Siamese balsa - SE Asia, New Guinea *'' Alstonia spectabilis'' R.Br. – poele bark, jackapple, leatherjacket, milky yellowwood - SE Asia, Papuasia, N Australia *'' Alstonia sphaerocapitata'' Boiteau - New Caledonia *'' Alstonia venenata'' R.Br. - S India *'' Alstonia vieillardii'' Van Heurck & Müll.Arg. - New Caledonia *'' Alstonia vietnamensis'' D.J.Middleton - Vietnam *'' Alstonia yunnanensis'' Diels - Yunnan, Guizhou, Guangxi

Gallery

Alstonia scholaris (Saptaparni) in Hyderabad, AP W IMG 1469.jpg, '' Alstonia scholaris'' Alstonia spectabilis Blanco2.379.png, '' Alstonia spectabilis'' Alstonia macrophylla (Batino) in Hyderabad W IMG 7138.jpg, '' Alstonia macrophylla''

References

* * Kade Sidiyasa, A., 3, 1992. A monograph of Alstonia (Apocynaceae). * {{Authority control Apocynaceae genera Taxa named by Robert Brown (botanist, born 1773)