Anogeissus (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Anogeissus (DC.) Guill. & Perr.

Protologue: Fl. Seneg. tent. 1: 279, t. 65 (1832).

Family: Combretaceae

Chromosome number: x= 12;A. latifolia:n= 12

• Axlewood (En). Burma (Myanmar): mai-hio, yon
• Laos: ben mon
• Thailand: takhian-nu
• Vietnam: râm, xôi.

Anogeissus comprises 8 species occurring in tropical Africa (1 species), southern Arabia (2 species), India, Sri Lanka, Nepal, Burma (Myanmar), Indo-China and Thailand.

The wood is mainly used for tool handles and other agricultural implements, and is a well-known substitute for hickory ( Carya spp.) and ash ( Fraxinus spp.). It is also used for general heavy construction (poles, rafters), boat building (masts), flooring, cart wheels, spokes and axles, sporting goods (hockey sticks, cricket stumps), sucker rods, pit props, turnery articles, and for furniture. Besides, it yields good charcoal and firewood, and when mixed with other species is suitable for the manufacture of writing and packing paper.

In India "ghatty gum" is tapped from A. latifolia . It is a good substitute for gum arabic and used in e.g. calico printing, for sweetmeats, in dye processes, and as a binding agent in pharmaceuticals. The leaves and bark are used for tanning and the leaves yield a black dye that is used commercially in India. Tussar silkworms are fed on its foliage which is also used as fodder for cattle. The medicinal use of A. latifolia for curing snake bites and scorpion stings has been reported from India.

Small amounts of Anogeissus are exported from India and Burma (Myanmar), mainly to Great Britain. Otherwise trade and utilization is on a local scale only.

Ghatty gum is exported from India on a small scale, a few hundred tons per year.

Anogeissus yields a heavy hardwood with a density of 760-940 kg/m³for A. acuminata and 870-1040 kg/m³for A. latifolia at 15% moisture content. Heartwood absent or small in diameter even in large trees, purplish-brown or dark brown, often with darker streaks, not clearly differentiated from the wide whitish-grey to greenish-grey or pale yellow to yellowish-grey sapwood; grain straight to shallowly interlocked; texture fine to medium and even. Growth rings usually indistinct, when distinct indicated by layers without vessels; vessels very small to medium-sized, solitary and in radial multiples of 2-4, often arranged in wavy oblique groups, usually open; parenchyma variable in abundance but often sparse, paratracheal vasicentric, aliform or confluent, and occasionally apotracheal in irregularly spaced bands; rays very fine, not visible to the naked eye; ripple marks absent; occasional intercellular canals of traumatic origin in tangential arrangement; pith flecks rare.

Shrinkage upon seasoning is moderate to high, and the wood is difficult to season as it is liable to warping, splitting and surface-checking. Green conversion during or at the end of the rainy season followed by stacking under cover to allow for slow drying is recommended. Kiln drying at low kiln temperatures is possible. The wood is hard, strong and very tough. It is difficult to saw, but with sharp tools it can be turned, machined and finished to a smooth surface. Reports on the durability are contradictory. The sapwood is probably susceptible to Lyctus . The heartwood is very resistant to preservative treatment. The energy value of A. latifolia is 17 600-20 500 kJ/kg.

Leaves and bark contain about 19% tannin.

See also the tables on microscopic wood anatomy and wood properties.

Deciduous, small to medium-sized trees up to 20(-36) m tall; bole straight and cylindrical or sometimes more poorly shaped, branchless for up to 8(-10) m, up to 80(-100) cm in diameter, occasionally with small buttresses; bark surface smooth or with small scales, pale to dark grey; branches drooping. Leaves opposite or subopposite, variably distichous, simple, entire, exstipulate, with greyish-yellow or whitish hairs below. Flowers sessile, in dense, globose heads on an axillary or terminal peduncle, 5-merous, small; sepals connate in a stalk-like tube, expanded at apex into a 5-lobed cup; petals absent; stamens 10, in 2 rows; disk intrastaminal, lobed; ovary inferior, 1-locular with 2 pendulous ovules, style simple. Fruit a 2-winged pseudo-achene, packed into a dense head, 1-seeded; calyx tube persistent and forming a beak. Seedling with epigeal germination.

Growth rates are fairly high; in natural forest in India the range of mean annual diameter increment of A. latifolia is 0.1-0.6 cm, compared with 0.6-1.1 cm for planted 16-years-old trees. A. acuminata trees reached a mean height of 12 m and a mean diameter of 7-10 cm 10 years after planting. In India A. latifolia is leafless in February-May, flowers in June-September depending on locality, and mature fruits are present in December-March. In Burma (Myanmar) flowering of A. acuminata has been observed in February-March, fruiting in April-May. The winged fruits seem adapted to wind dispersal.

Anogeissus species are found in deciduous or semi-evergreen forest, up to 1300 m altitude. They are common elements in teak forest but also occur in the understorey of dipterocarp forest, in mixed deciduous forest, in bamboo forest and even in vegetation under semi-arid conditions like savanna woodland and dry rocky hills. Associated species include Indian walnut ( Albizia lebbeck (L.) Benth.), Indian rosewood ( Dalbergia spp.), Indian rose chestnut ( Mesua ferrea L.) and keruing ( Dipterocarpus spp.). The average annual rainfall for A. latifolia is 225-625 mm, the absolute maximum temperature is 38-45C and absolute minimum temperature is -1-16C. It is found on a variety of soil types but prefers deep alluvial soils. It may form pure stands on e.g. sandstone, and does not tolerate waterlogging.

Silviculture Silvicultural information is mainly based on Indian experience. Anogeissus can be propagated by seed and tissue culture; the latter technology has been performed on an experimental scale only. Seed viability is extremely low, never more than 3%. It has been suggested that the viability of A. latifolia seed increases after a very dry season. In 15 germination tests executed in Burma (Myanmar) seed of A. acuminata proved to be completely unviable. There are 105 000-125 000 seeds of A. latifolia or 39 000-63 000 dry fruits of A. acuminata in 1 kg. Seed should be sown under shade. Germination starts about 20 days after sowing. Seedlings of A. latifolia attain 10-20 cm height and develop a taproot of 45 cm in the first growing season. Stumps from 1-year-old seedlings proved to be the best planting stock. Young trees are very intolerant of weed competition. Anogeissus trees are light demanding but they can stand slight shade when very young. The trees produce root suckers and coppice and pollard well; they should not be coppiced or pollarded in the rainy season. Planted A. acuminata performed best with a mean annual rainfall of 750-1250 mm on deep loamy soils. A. latifolia has been tried extensively in India, but generally with disappointing results. Natural regeneration of both Anogeissus species, however, is very good. The use of wildlings could prove interesting for artificial regeneration of Anogeissus .

As both A. acuminata and A. latifolia are widespread and often common, they do not seem to be endangered, except perhaps as a result of excessive collection of gum. There are no records of orchards or germplasm collections of Anogeissus species.

Trials in South-East Asia with Anogeissus , in particular A. acuminata , are recommended to determine its potential as a fairly fast producer of excellent timber under comparatively dry conditions.

111, 163, 218, 343, 392, 455, 464, 536, 571, 923, 924, 932, 933, 963, 999, 1038, 1052, 1064, 1098, 1104, 1169, 1177.