Ehretia (PROSEA)
Introduction |
Ehretia P. Brown
- Protologue: Civ. nat. hist. Jamaica: 168 (1756).
- Family: Boraginaceae
- Chromosome number: x= unknown;E. acuminata:n= 18, 2n= 30
Vernacular names
- Indonesia: kendal
- Philippines: tanaua (general)
- Thailand: kom.
Origin and geographic distribution
Ehretia comprises about 50 species. Three of these occur in Central America, the rest in the tropics and subtropics of Africa, Asia and Australia. Within the Malesian region 12 species are found.
Uses
The wood of Ehretia is used for construction, furniture, household utensils, tool handles and for framing and decking of small boats. It may be suitable for sporting goods requiring a strong, tough wood.
The fruit of E. acuminata is edible and its foliage is used for fodder in India. The very young leaves used to be exported from India to Tibet, where they were mixed with tea.
Production and international trade
Utilization of the wood of Ehretia is probably only local and on a small scale.
Properties
Ehretia yields medium-weight hardwood with a density of 490-670(-715) kg/m3at 15% moisture content. Wood pale brown, pale yellow or yellowish-brown; grain interlocked; texture moderately coarse and uneven owing to wide growth rings; wood fairly lustrous. Growth rings distinct, ring-porous; vessels moderately small to moderately large, arranged more or less concentrically with growth rings, vessels in earlywood mostly solitary, in latewood often in radial multiples of 2-4 and in clusters, tyloses present; parenchyma apotracheal in irregularly spaced bands and diffuse and diffuse-in-aggregates; rays both wider and narrower than the vessels; ripple marks absent.
Shrinkage upon seasoning is low and the wood is not subject to checking. The wood works satisfactorily. The heartwood is very resistant to dry-wood termites. The sapwood is non-susceptible to Lyctus .
E. acuminata leaves contain 11-22% crude protein.
See also the tables on microscopic wood anatomy and wood properties.
Botany
Evergreen or deciduous shrubs or small to medium-sized trees up to 30 m tall; bole straight, up to 65(-80) cm in diameter, fluted at base; bark surface brown or greyish, finely fissured, inner bark soft, fibrous, pale yellow. Leaves alternate, simple, entire or serrate, sometimes wavy, with reticulate venation; stipules absent. Flowers in a many-flowered cyme, corymb or panicle, 5-merous; calyx imbricate; corolla tubular to campanulate, white or pale yellow; ovary superior, 2-carpellate with 2 ovules in each cell; style 1, terminal, divided in 2 branches. Fruit a drupe with fleshy to mucilaginous mesocarp, splitting up into two 2-seeded or four 1-seeded pyrenes.
A mean annual diameter increment of 0.6-0.8 cm has been measured in wood samples. Trees of E. javanica flower when completely leafless. Pollination is by insects.
Ehretia is sometimes placed in the small family Ehretiaceae , a split off product from the Boraginaceae . E. acuminata is highly variable and formerly many varieties were distinguished. Records of E. timorensis Dcne from Peninsular Malaysia all refer to E. dichotoma , as E. timorensis is a rare endemic of Timor.
Ecology
Ehretia trees occur scattered in well-drained lowland to montane forest, up to 2100 m altitude. E. dichotoma also occurs on limestone.
Silviculture
Ehretia can be propagated by seed. The germination rate of untreated seeds of E. acuminata is about 50%, whereas it is about 90% for seeds treated for 10 minutes with concentrated sulphuric acid.
Genetic resources and breeding
The timber-yielding Ehretia species have a fairly wide geographical distibution, but their scattered occurrence makes them vulnerable to genetic erosion. However, E. philippinensis has a narrow distribution, but is more abundant.
Prospects
The wood seems to be of good quality and has even been compared with teak ( Tectona grandis L. f.). It is unlikely to gain importance, however, as it is found only very locally.
Literature
70, 163, 436, 464, 465, 504, 568, 595, 772, 793, 821, 861, 934, 946, 971, 1038, 1104, 1164, 1169, 1221.