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10. Acacia tortilis
Botanical Name Acacia tortilis (Forsk.) Hayne
Common Names umbrella-thorn (Africa); haak-en-steek, haaken-steekdoring,
sambreeldoring (South Africa); sayal, samor (Egypt, Sudan); seing,
tortilis (Senegal); kandili, bisaw (Niger); seyal, sayyal (Arabic); mgunga (Tanzania);
Israeli babool (India).
Legume Family, Leguminosae (Mimosoideae}
This tree or shrub, one of the most widespread species of Acacia in Africa
and the Middle East, is recognized by paired spines of 2 kinds, both -hortcurved
and long-straight, small bipinnately compound leaves, white to pale
yellow flowers in ball clusters, and pods curved and twisted, often in a spiral.
It is drought-resistant and produces superior firewood and charcoal. The
scientific name, meaning "twisted," describes the pods. The common name
"haak-en-steek" means "hook-and-prick" in reference to the 2 kinds of spines of
this fuelwood species for arid and semiarid regions.
Description Small to medium-sized spiny deciduous or nearly evergreen
tree mostly 4-15 m high (rarely 20 m), with trunk branching low; sometimes
with several spreading crooked trunks 20 cm or more in diameter. Small trees
with rounded crown, larger trees with widespreading flat-topped crown suggesting
an umbrella, of dense, fine feathery foliage. Under extreme aridity, a
low shrub of Im; under heavy grazing, reduced to trailing, seemingly unconnected
branches radiating from a low sand mound. Produces long lateral roots.
Bark gray or dark brown to blackish, rough, deeply furrowed, scaly. Twigs
gray-green to reddish-brown, mostly hairy. Spines from stipules paired at
nodes, of 2 kinds with both often on same twig; curved or hooked, brownish,
mostly under 5 mm long, others long-straight and white, 1-5(-9) cm long.
Leaves 2-6 at a node, bipinnately compound, small, 15-35 mm long, with
4-10 pairs of side axes (pinnae) 5-10 mm long, each bearing 7-15 pairs of
crowded, tiny, narrow leaflets 1-5 mm long, bluish gray green, finely hairy.
Flower clusters (heads) like balls, in masses over tree, 1-4 on slender stalks
at leaf base, 7-10 mm in diameter, white to cream or pale yellow, fragrant.
Flowers many, crowded, stalkless, about 4 mm long, composed of 5-toothed
calyx 1mm long, 5petals 2 mm long, many threadlike stamens, and pistil with
threadlike style.
Pods (legumes) narrow, 8-12 cm long, 5-9 mm wide, slightly flattened and
narrowed between seeds, much curved and twisted, often in a spiral like a coil
spring, hard, yellow-brown, slightly narrowed between seeds, often finely
hairy, not opening. Seeds several, beanlike, elliptical, 6-7 mm long, light
brown.
Wood reddish with whitish sapwood, heavy. Warps upon drying and often
riddled by borers. This wood of high calorific value used mainly for superior
ACACIA TORTILIS
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