Croton (PROSEA Timbers)
Introduction |
Croton L.
- Protologue: Sp. pl. 2: 1004 (1753); Gen. pl., ed. 5: 436 (1754).
- Family: Euphorbiaceae
- Chromosome number: x= 10; 2n= unknown for Malesian species
Vernacular names
- Silver croton (En). Brunei: kemarik
- Indonesia: caporimbo (Jambi, Sumatra), parengpeng (Sundanese), walik lar (Javanese)
- Malaysia: cheret budak, chenderai gajah, melokan (Peninsular)
- Philippines: tubang-puti (Filipino)
- Laos: khai2don1, sa 'lot, 'sê 'lot
- Thailand: plao (central).
Origin and geographic distribution
Croton is a very large genus of at least 800 species, the majority in America, but with some 200 species in the Old World tropics. Some 45 species occur in Malesia, most of them in East Malesia. The only timber-yielding species is C. argyratus Blume (synonyms: C. budopensis Gagnep., C. maieuticus Gagnep., C. tawaoensis Croizat) which is found in Burma (Myanmar), Indo-China, Thailand, throughout the Malesian region (except for New Guinea), and in northern Australia.
Uses
The wood of Croton is used for poles in house construction and for agricultural implements like tool handles.
The seeds yield an oil used in lamps. Some goat ranchers in the Philippines use live fences of Croton .
Production and international trade
Croton wood is used rarely and on a local scale only.
Properties
C. argyratus yields a medium-weight to heavy hardwood with a density of 735-930 kg/m3at 15% moisture content. Heartwood pale yellow, not clearly differentiated from the sapwood; grain straight; texture rather fine and even. Growth rings absent; vessels moderately small, mostly in radial multiples of 2-7; parenchyma abundant, apotracheal in narrow bands, and diffuse-in-aggregates, distinct with a hand lens; rays extremely fine or moderately fine, the latter visible to the naked eye; ripple marks absent; occasionally with traumatic vertical canals.
The wood seasons well and is hard. Its durability has not been well established. Discolouration by sap-stain has been reported.
See also the table on microscopic wood anatomy.
Botany
An evergreen, monoecious, small to medium-sized tree up to 27 m tall; bole fairly straight, cylindrical, up to 70(-170) cm in diameter, without buttresses; bark surface finely fissured, greyish. Leaves arranged spirally, simple, entire to denticulate; blade cordate, with 2 glands at base, scaly below; stipules oblong, caducous. Flowers unisexual, in a terminal thyrse with female flowers solitary at base and male ones in cymules towards the apex; sepals 5, imbricate. Male flower with 5 petals; disk composed of 5 glands; stamens numerous, inflexed in bud; pistillode absent. Female flower without petals; disk annular; ovary superior, 3-locular with 1 ovule in each cell, styles 3, bifid. Fruit a capsule splitting into 3 or 6 parts, with a persistent calyx. Seed small, smooth. Seedling with epigeal germination; cotyledons emergent, leafy; hypocotyl elongated; all leaves arranged spirally.
In Java C. argyratus has been observed flowering throughout the year.
Ecology
C. argyratus is found mainly in secondary rain forest and occasionally in monsoon forest including teak forest, up to 1000(-1500) m altitude. It usually occurs in well-drained locations on sandy clay, sandy loam, heavy loam with limestone, or basaltic soils.
Silviculture C. argyratus can be propagated by seed which has about 45% germination in 22-73 days.
Genetic resources and breeding
There are no records of ex situ conservation of C. argyratus . Its wide area of distribution and occurrence in secondary vegetation make it unlikely to be at risk of genetic erosion.
Prospects
No increase in the use of Croton wood is foreseen.
Literature
26, 28, 33, 34, 36, 70, 162, 163, 209, 267, 364, 436, 464, 543, 829, 831, 861, 963, 974, 1038, 1169, 1194, 1195, 1221, 1256.
C. Phengklai