Rhodoleia (PROSEA)
Introduction |
Rhodoleia Champion ex Hook.
- Protologue: Curtis' Bot. Mag., ser. III, 6: t. 4509 (1850).
- Family: Hamamelidaceae
- Chromosome number: x= 12;R. championi: 2n= 24
Vernacular names
- Indonesia: kasiebranah (Sumatra), sialagundi (Tapanuli)
- Malaysia: kerlik, keruntum (Peninsular)
- Vietnam: lôt.
Origin and geographic distribution
Rhodoleia is probably monotypic and is distributed from Upper Burma (Myanmar) to southern China, Hainan and Vietnam, and in Peninsular Malaysia and Sumatra. The only species is R. championi Hook. (synonyms: R. ovalifolia Ridley, R. subcordata Exell, R. teysmannii Miq.). In recent years 3 new species have been described from China but these may well prove to be synonymous with the former one.
Uses
The wood of R. championi is used for interior finish.
R. championi has been planted in Peninsular Malaysia, mountainous parts of West Java and probably also in China for ornamental purposes. In Sumatra it has been planted as a fire-break.
Production and international trade
Utilization of the wood of R. championi is very limited and on a local scale only.
Properties
R. championi yields a medium-weight hardwood with a density of 645-860 kg/m3at 15% moisture content. Heartwood red-brown, not sharply differentiated from the paler sapwood; grain interlocked; texture fine and even; wood with narrow stripe figure on radial surface due to alternating grain; wood lustrous, fragrant when fresh. Growth rings usually not distinct, occasionally indicated by a narrow layer of denser tissue; vessels very small to moderately small, mostly solitary with few radial pairs, angular, open; parenchyma absent; rays fine, not always visible to the naked eye due to lack of contrast in colour; ripple marks absent.
The wood seasons moderately fast with slight surface and end checking. The wood is strong and can be fairly easily sawn. It takes a very smooth finish and an excellent polish. It is durable for interior use, but non-durable when exposed to the weather or in contact with the ground.
See also the table on microscopic wood anatomy.
Botany
Evergreen, small to medium-sized trees up to 25(-33) m tall; bole up to 45(-100) cm in diameter; bark surface smooth, with large lenticels and scaly patches, inner bark firm, pink-buff, spotted brown inwards. Leaf buds rounded, scaly. Leaves arranged spirally, simple, entire, with long petioles, leathery, bluish-grey to whitish below; stipules generally present only in the transition zone between bud scales and foliage leaves. Flowers connate, 5-10 together in a large, nodding, peduncled head with an involucre of 12-20 bracts and resembling a single flower, bisexual; sepals connate; petals only well developed and rayed along the outer margin of the head, red; stamens 7-11; disk absent; ovary semi-inferior, (1-)2-locular with many ovules in each cell, styles 2, long and slender. Fruit a 4-valved, woody capsule, basally connate. Seed 10-20 per cell of which 0-1 is fertile.
Vegetative growth is flush-wise. In Java flowers have been observed throughout the year, but in Hong Kong flowering seems restricted to February and March. Birds, such as sun-birds, and various kinds of insects (bumble bees, flies, wasps) have been observed to visit the flowers. The flowers produce nectar, starting at daybreak, and have sticky pollen. The fruit takes about 6 months to mature.
Rhodoleia is the only genus of the subfamily Rhodoleioideae . It used to be thought that it lacked stipules, until it was discovered that these are restricted to certain parts of the plant (see above). R. championi is highly polymorphic and was formerly divided into at least 7 distinct species.
Ecology
R. championi occurs in primary forest or rarely in secondary vegetation, at (350-)1400-2500 m altitude.
Silviculture R. championi can be raised from seed. There are about 440 000 dry seeds per kg. Seeds of R. championi germinate in 10-24 days. Wildlings have been used for reforestation, but mortality was fairly high.
Genetic resources and breeding
The risk of genetic erosion is low, as R. championi is hardly harvested for its timber and is planted as an ornamental.
Prospects
In the future its use as an ornamental may become more important than as a timber.
Literature
70, 163, 267, 279, 314, 341, 343, 379, 405, 709, 790, 829, 831, 861, 1221, 1242.
E. Boer & M.S.M. Sosef