Revision of AnnesijoA, elAteRiospeRmum And the intRoduced species of heveA in mAlesiA (euphoRbiAceAe)

Annesijoa is an endemic monotypic genus from new guinea with as single species A. novoguineensis. Elateriospermum is also monotypic (E. tapos) and found in West Malesia. the South American genus Hevea comprises about 10 species. one species (H. brasiliensis) is presently cultivated worldwide in plantations for its rubber and has become one of the major economic products of SE Asia. two other species, H. guianensis and H. pauciflora are sometimes present in Malesian botanical gardens.


IntroDUCtIon
three genera are revised for Flora Malesiana, Annesijoa Pax & K. Hoffm., Elaterio spermum Blume, and Hevea Aubl.these genera are not very closely related, but they are all part of the subfamily Crotonoideae (Webster, 1994;radcliffe-Smith, 2001), though classified in different tribes (Jatropheae, Elateriospermeae, and Micrandreae subtribe Heveinae, respectively).typical for the Micrandreae are colporate pollen with a reticulate sexine, articulate laticifers, absent petals, and plenty of endosperm (oily in the Heveinae).The Jatropheae and Elateriospermeae share inaperculate pollen with a typical 'crotonoid' sexine, inarticulate laticifers, petals absent or not, and seeds with or without endosperm.they differ in several characters, the Elateriospermeae lack endosperm and have no petals, while these are present in the Jatropheae.
the three genera can easily be distinguished from each other.Hevea and Elaterio spermum have white latex, whereas Annesijoa has variable latex ranging from clear to white to red.Hevea and Elateriospermum have glands at the transition from petiole apex to blade base, these are absent in Annesijoa.Elateriospermum has simple leaves, whereas the other two genera have compound leaves, trifoliolate in Hevea and 3-5(-7)-digitate in Annesijoa.Annesijoa and Hevea (and Bischofia) are the only Euphorbiaceae genera with compound leaves in Malesia.other genera sometimes have deeply dissected leaves like some species of Manihot Mill.and Jatropha L. (genera relatively closely related to Annesijoa and Hevea).In the tribe Jatropheae there are also two other genera with compound leaves, the South American Joannesia Vell.and the West African Leeuwenbergia Letouzey & n.Hallé (both with 2 spp.). the stamens of the three genera treated are also quite different.Annesijoa has 15-25 united stamens in three layers, Hevea has 4-10 united stamens in one or two layers, and Elateriospermum has 10-20 (-22) free stamens in a single bundle.
Annesijoa and Elateriospermum are monotypic, indigenous genera in Malesia.Annesijoa is endemic in new guinea and Elateriospermum is found in West Malesia.Hevea is originally found in South America, but it was introduced very successfully in Malesia.Several other species are only present in botanical gardens.Hevea brasiliensis is the major source of natural rubber in the world (out competing Manihot carthagin ensis (Jacq.)Müll.Arg.subsp.glaziovii (Müll.Arg.)Allem.The production in SE Asia is excellent and due to the many cars and the HIV infection the demand for natural rubber is high, therefore it is planted in many plantations all over SE Asia.nowadays, the wood (very light-coloured with beautiful patterns) is increasingly popular, providing new challenges to the rubber plantations.

AnnesijoA
Pax & Hoffmann (1919) described the monotypic genus Annesijoa.the name is an anagram of Joannesia.Annesijoa is easily recognised, because it is one of the very few genera in the Euphorbiaceae with a compound, digitate leaf, with variable latex.Its flowers with white petals make it an attractive plant.However, the horticultural value is probably low, because it is a large tropical tree.Webster (1994) and radcliffe- Smith (2001) classify Annesijoa in the subfamily Crotonoideae, tribe Jatropheae.Within the tribe Annesijoa shares a compound leaf with the South American Joannesia and the West African Leeuwenbergia (both with two species).However, the latter two have 2-locular ovaries, drupaceous fruits (or fruits unknown, respectively), and much broader stigmas (Annesijoa has a 3-localur ovary, dehiscent fruits, and slender, bisected stigmas).
Note -The literature is not clear about the presence of latex in Annesijoa, while the specimens examined are variable and mention the latex to be slightly sticky to sticky, clear to white to red (LAE 51712, NGF 31831, Pullen 7319).

ELATERIOSPERMUM
Blume (1825) described the monotypic genus Elateriospermum.Elatérios is Greek for to chase away, sperma refers to seed: plant of which the seeds are launched by the fruit during dehiscence (a character rather typical for most Euphorbiaceae).Typical characters are the presence of white latex; obovate, long-petioled, simple leaves with two glands at the base of the blade; staminate flowers with 4 or 5 imbricate sepals, no petals and 10-20(-22) stamens; pistillate flowers with 4-6(-7) sepals (the variation is somewhat larger than described by Radcliffe-Smith, 2001).Elateriospermum is classified by Webster (1994) and Radcliffe-Smith (2001) in the subfamily Crotonoideae and the monogeneric tribe Elateriospermeae.Typical characters are: Monoecy, white latex, slender obovate leaves on a long petiole with adaxial, apical glands, absent petals, disc, pistillate flowers with staminodes, large fruits, inaperturate, crotonoid pollen.

Elateriospermum Blume
Elateriospermum Blume (1825)   Vernacular names -thailand: Kra, pra (thai); pi-ra (Bidayuh-Malay) (Smitinand, 2001).Malay Peninsula: (Buah) perah, perah kokong (Burkill, 1935;Whitmore, 1973); gua pra, ple prah (Sakai); piah, suing (Semang).Sumatra: Asiloem (Karo); daun tepoes, kajoe si marsang-sang, kedoei, tapoes.Java: Tap(p)os (Sundanese) (Blume, 1825).Borneo: Bramban; kelampai (Iban-Sarawak); layang layang; paha; perah, perah ikan (Malay); rampeh, rapi (Bidayuh) Uses -A tree of ornamental value.Its flowering indicates the start of the rice season.the seeds are mainly used, but they are usually poisonous (cyanide) when fresh (though a few races are without cyanide).the seeds can be eaten cooked or roasted, but too much may cause dizziness.on Sumatra a paste is made of the seeds (pounded with some water) and used to flavour some kinds of sambal; jungle tribes (Sakai) in Malaysia bury the paste packed in a bag or in bamboo in wet earth for a month or more, the result is a fermented paste with a strong flavour, which is highly appreciated with meals.The fermented paste is also used as fish bait.The oil is seldom pressed from the seeds, pale yellow, nearly odourless and with a nice taste, to be used for cooking or as lamp oil. the wood is usually considered as excellent.the sapwood is white, the heartwood with beautiful dark brown flames.However, it is mainly used as firewood or for small items like handles of rubber tapping knives, because it takes a nice polish.It could have been a good construction timber, but only the sapwood is durable, the heartwood rots easily or is attacked by termites unless treated with preservatives. the seeds make nice toys for children, they are used as toy beetles or threaded together in a game called 'conquerors'.the latex is used on Sumatra to shield dirty wounds, because it dries quickly; the Bidayuh in Sarawak apply fresh latex once per day to crack wounds on the soles of their bare feet.the latex is also used to polish blowpipes to a glossy dark sheen (Malay Peninsula).Partly after Heyne (1927) and Burkill (1935).
heveA Aublet (1775) described Hevea.He used the name erroneously, because it refers to the Ecuadorian Indian name 'hevé', which is Castilla elastica Cerv.(Moraceae).However, the description and plate of Aublet is of such quality that the correct identification of his plant is without doubt.Schultes (1970a, b) described the history of Hevea, but this part is rather brief and the references are missing.According to him, four years later richard proposed a new name for Hevea: Siphonia.However, the only reference to Siphonia and richard is in Von Schreber's edition of Linnaeus' genera Plantarum of 1791, where there is indeed also a reference to Aublet's name Hevea.this makes Siphonia in fact a superfluous name, because Hevea is nomenclatorally correct, even though the vernacular name refers to another plant.gmelin (1791) introduces the name Caoutchoua elastica for Aublet's Hevea guianensis, referring to a name in Linnaeus (1781), Jatropha elastica.this is again a superfluous name as Aublet is also referred.Finally, robert Brown (Bennett & Brown, 1844) introduced the fourth genus name, Micrandra (M.ternata), a name now rejected in favour of Bentham's Micrandra (erroneously a genus thought to be closely related to Hevea).
Hevea comprises about 10 species, all from South America.However, H. brasil iensis has become one of the most economically important species worldwide and is cultivated in plantations for its exudate, of which mainly rubber is made.Hevea is classified by Webster (1994) and Radcliffe-Smith (2001) in the subfamily Crotonoideae, tribe Micrandreae, subtribe Heveinae.the genus is easily recognised, because it is one of the very few genera in the Euphorbiaceae with a trifoliolate leaf and white latex, leaflets papery, flower actinomophic, calyx 5-or 6-lobed, stamens 5-10 united in 1 or 2 layers, ovary 3-5-locular, the fruits large capsules and the seeds are big for Euphorbiaceae and show a kind of camouflage design with areas of different shades of yellow to brown.
Because we are dealing with one widely cultivated species and two occasional species in botanical gardens, the nomenclature is kept simple, only the accepted name is presented and synonyms based on the same type.Most species concepts in Hevea are complicated and many synonyms and infraspecific taxa were described.hevea Aubl.
Distribution -only known from cultivation, originally only from Amazonian South America, presently cultivated worldwide in tropical regions.
Habitat & Ecology -reported wild and common in evergreen forest, probably escaped from abandoned plantations; once reported from limestone.Altitude: sea level up to 200 m.Flowering and fruiting throughout the year.
Uses -of high economic value.the bark is tapped for its latex by making shallow, V-shaped cuts over 1/3 of the circumference, working from c. 2 m high toward the root, moving to the next third once a row is finished.The latex comprises elastic strings of polymers of cis-polyisoprene, which, when still unvulcanised, are easily detached from each other and they are therefore used in chewing gum [nB: Hevea is one of the few Euphorbiaceae with a non-poisonous latex].Vulcanised (mixed with sulphur and baked) the strings become solidly attached to each other and have many applications as rubber.Natural rubber is more elastic and durable than artificial rubbers.Its main use is undoubtedly in tires (next to condoms due to the HIV virus).the tires are presently more and more re-used as furniture, shoes, and waste baskets in SE Asia and in a new kind of tarmac in Europe.
When the latex production of the fast growing trees decreases they are cut and the wood, though not durable and strong, is more and more used in thailand for the production of beautiful, light coloured furniture and wooden toys for children.
note -the interpretation of Hevea brasiliensis is difficult, because it is only known from cultivation and, consequently, many synonyms, varieties, cultivars, etc. have been described in the course of time.This is not the only difficulty, also the correct interpretation of the concept of the species and the first publication of the name are troublesome.De Jussieu (1824) published the name Siphonia brasiliensis first, but this is apparently a nomen nudum.Luckily the ICBn allows detailed drawings to be valid descriptions and De Jussieu's plate is very detailed.This is fortunate because one year later Kunth (1825) also used the name Siphonia brasiliensis for two distinct plants, one from Venezuela (orinoco) and the other from Brazil (lower Amazon). the latter is the cultivated species.De Jussieu used a specimen from the Willdenow herbarium.there are three sheets named Siphonia brasiliensis, but only one is identified as Hevea brasiliensis by Schultes, the others bear the identification H. pauciflora.this means that only one sheet should be taken as lectotype.
Habitat & Ecology -Flowering: August to october; fruiting: november to December.