Hevea brasiliensis
(Willd. ex A. Juss.) Mueller-Argoviensis in Linnaea 34(1865) 204.

Siphonia brasiliensis
Wildenow ex A. Juss., Euphorb. (1824) 40, t. 12, fig. 38B, 1-6

Hevea janeirensis
Mueller-Argoviensis in Martius, Fl. Bras. 11, pt. 2 (1874) 706.

Hevea Sieberi
Warburg, Kautschukpfl. (1900) 33.

Hevea brasiliensis
(Willd. ex A. Juss.) Mueller-Argoviensis var. angustifolia [Ule apud] Huber in Bol. Mus. Goeldi 3 (1902)350.

Hevea brasiliensis
(Willd. ex A. Juss.) Mueller-Argoviensis var. latifolia [Ule apud] Huber in Bol. Mus. Goeldi 3(1902) 350.

Hevea brasiIiens/s
(Willd. ex A. Juss.) Mueller-Argoviensis fma. angustifolia Ule in Tropenpfl. Beih., 6(1905)8.

Hevea brasiliensis
(Willd. ex A. Juss.) Mueller-Argoviensis fma. latifolia Ule in Jropenpfl. Beih. 6(1905)8.

Hevea Randiana
Huber in Bol. Mus. Goeldi 4 (1906)636.
Hevea bras/liens/s
(Willd. ex A. Juss.) Mueller-Argoviensis var. stylosa Huber in Bol. Mus Goeldi 4(1906)640.

Hevea brasiliensis
(Willd. ex Adr. Juss.) Mueller-Argoviensis var. janeirensis (Muell.-Arg.) Pax in Engler, Pflanzenr. 4, Fam. 147(1910)121.

Hevea brasiliensis
(Wilid. ex A. Juss.) Mueller-Argoviensis var. cuneata (Hub.) Pax in Engler, Pflanzenr. 4, Fam. 147(1910)123.

Hevea brasiliensis
(Willd. ex Adr. Juss.) Muelier-Argoviensis var. Randiana (Hub.) Pax in Engler, Pflanzenr. 4, Fam. 147(1910)123.

Hevea Granthami
Bartlett in Bot. Gaz. 84(1927)200, nom. altern.

Hevea brasiliensis
(Willd. ex Adr. Juss.) Mueller-Argoviensis Mut. Granthami Barlett in Bot. Gaz. 84(1927)200.

Hevea brasiliensis
(Willd. ex Adr. Juss.) Mueller-Argoviensis fma. typica Ducke in Arch. Jard. Bot. Rio Jan. 6(1933)55.

Hevea brasiliensis
(Willd. ex Adr. Juss.) Mueller-Argoviensis fma. Randiana (Hub.) Ducke in Arch. Inst. Biol. Veg. Rio Jan. 2(1935)224.

Hevea brasiliensis
(Wuld. ex Adr. Juss.) Mueller-Argoviensis fma. subconcolor Ducke in Arch. Inst. Biol. Veg. Rio Jan. 2(1935) 224.

Siphonia Ridleyana
Cook in Journ. Wash. Acad. Sci. 31(1941)46.

Hevea brasiliensis
(Willd. ex A. Juss.) Mueller-Argoviensis fma. acreana (Ule) Ducke in Bol. Tecn. Inst. Agron. Norte, No.10(1946)23.

Stout trees up to occasionally 150 feet (but usually more or less 100 feet) tall, with a foliose crown. Trunk cylindrical but frequently rather swollen towards the base, not uncommdnly up to 3 feet in diameter (sometimes much larger). Bark variable: smooth, thin, hard and brittle and internally tan or sand-coloured or thick, softer and internally reddish or dark purplish. Latex white or cream-coloured, thick, usually abundant, yielding a very high quality rubber. Branches greyish brown or greyish red. Flushes inconspicuous. Bud scales in narrow rings, few to a dozen, linear-triangular, 3-5 mm. long, soon deciduous. Leaves falling well before flowering.

Mature leaflets strongly reclinate, rigidly membranaceous, glabrous, glossy, dark green above, sometimes paler but frequently sub- concolourous beneath, lanceolate-elliptic to broadly lanceolate, usually long acuminate, basally acute or cuneate, varying between 3-11 cm. long, 2-8 cm. wide, mid-vein extending to apex but not calloused. Inflorescence usually shorter than the leaves, more or less pyramidal, many-flowered. Flowers bright or cream-yellow, extremely pungent-aromatic. Staminate buds narrowly ovoid-conic, acuminate, somewhat contorted, rather whitish-tomentellous; staminate flowers 5-6 mm. long, and a disk inconspicuous, urceolate, slightly 5-lobed; ovary densely white-sericeous with sessile stigmas. Capsule green sub-globose, apiculate; strongly igneous, thick, not contorted at dehiscence. Seeds variable in size and shape but usually ellipsoidal, ventrally some-what compressed but not angled, 15-32 mm. long, 14-25 mm. in breadth, basally grey-brown with dark brown mottling.

Ranging almost wholly south of the Rio Amazonas in the Amazon Valley and into the Matto Grosso region, Hevea brasiliensis is found in several very different ecological situations: along deeply flooded rivers in areas where, even during the drier periods, the soil remains boggy; along the banks of water courses subjected to short periods of inundations; and, in the southwesternmost regions of its distributio~in the Brazilian Acre, the Peruvian Mad re de Dios and the Bolivian Ben i~n high, well drained soil never subjected to the annual high waters. There exist numerous geographically delimited strains or ecotypes as well .as several easily distinguished bark types that cap be associated with geographical and ecological ranges (Ule, 1914; La Rue 1926; Schultes, 1987).

The Hevea brasiliensis growing on high ground not subject to flooding in the south-western Amazonia yields the highest quality rubber. If in 1876 wickham had been able to collect his seed in this far-oft area, the clonal material in plantation use might have been either different or perhaps the source of a superior rubber. The wickham material, upon which modern plantation material from the Eastern Hemisphere has been based, represents only one ecotype of Hevea brasliensis from seeds from a few trees in one locality - a very restricted source of germ-plasm (Wycherly, 1976; Schultes, 1977a, 1987). But spectacular improvements have nevertheless been made in the century since domestication of the species.

Hevea brasiliensis, in the plantations of the Eastern Hemisphere, is all descended from material introduced from the eastern Amazon of Brazil - the region of Santarém at the mouth of the Rio Tapajóz. The tree in plantations is atypical, extraordinarily different from the development of the tree in the undisturbed Amazon forests; this condition may be due in part to lack of the protection of a climax over-storey. In plantation practice it is a.smaller and weaker tree with a noticeably meager crown. Furthermore, it is not allowed to grow to the great age of trees in the wild.

A most unusual variant of Hevea brasiliensis in which cork cambium produces true cork to a thickness of 16 mm. was described in 1927 and given a name: H. brasiliensis mut. Granthami (Bartlett, 1927). It was an outstanding yielder of rubber. The advantages of a high yielder with soft, thick, corky bark are obvious, but this varient apparently aroused no further interest and has apparently been lost.

The several bark types are known by Brazilian names. Seringueira prêla ('black barked rubber') is common in the western half of the Amazon Valley, rare in eastern Amazonia; it prefers low, heavily inundated river- banks. Its bark, thicker and softer and of a purplish cotour, is much easier to tap than other types of bark of H. brasiliensis. The bark type which is most frequent in the eastern Amazon (and in many localities the only type) is known as ser/ngueira branca ('white barked rubber') and is thinner, harder, more brittle and much more difficult to tap; it has a tawny sand colour. This type prefers sites just above the more or less permanently boggy river banks but in areas still annually flooded.

The scientific evaluation of these bark types has not yet fully been made, but the differences are marked and are recognised by every rubber tapper, inasmuch as the tapping circuit ('estrada') with a preponderance of the seringueira prêta is much easier to tap and many more trees can be cut than in an estrada which is made up primarily of seringueira branca.. There is evidence that latex from the seringueira prêta trees is of somewhat better quality than that supplied by the seringueira branca trees (La Rue, 1926; Schultes, 1987).

The ecotype of Hevea brasiliensis from the Santarém area is all of the seringueira branca type, and even of this type it does not represent the best ecotype. But in 1876, it would have been impossible for Wickham to gather rubber seeds in the western regions, because transportation would have been much too slow for the short-lived rubber seeds to survive in viable condition, especially after a long trip overseas in sailing ships. Had Sir Henry been able to get seeds from the Acre or Madre de Dios areas in south-western Amazonia - where Hevea brasiliensis yields an extraordinarily high grade of rubber - the story of the Asiatic plantations would most certainly have been quite different. This very superior rubber is known in the commerce as seringa Acre fina.

Extract from: A Brief Taxonomic View of the Genus Hevea, by Richard Evans Schultes. Kuala Lumpur: MRRDB, 1990.