What Does It Look Like?
What is it?
Giraffe Thorn (Vachellia erioloba) [as Acacia erioloba] is a long-lived large shrub or small tree with an upright habit usually growing 2–6 m tall and spreading up 10 m across. Very old trees may reach 20 m in height. Old branches have rough, deeply-furrowed, dark grey to blackish-brown bark and often become considerably contorted. Young stems usually have a zig-zagging nature, and are reddish-brown and shiny. Prominent thorns, up to 6 cm long and often with swollen bases, are produced in pairs at the base of each leaf. These are almost straight, and whitish or brown. Leaves are medium green or bluish-green and up to 6 cm long. Each leaf consists of 1–5 pairs of branchlets each bearing 8–18 pairs of small oblong or elongated leaflets.
The 'wattle-like' flowers are borne in small, bright yellow, rounded and fluffy clusters about 8–15 mm across and they are borne singly in the leaf forks.
The fruit are large woody pods, 11–12 cm long and 4–6 cm across, that have a covering of velvety hairs giving them a greyish appearance. These pods are variously described as being half-moon shaped, kidney-shaped, ear-shaped or roughly sickle-shaped. Unlike other Vachellia [as Acacia] species the pods do not split open, even at maturity, but are consumed by animals. They are spongy inside, and contain several reddish-brown coloured seeds (Faithful & Blood 2001; Navie 2004).
For further information and assistance with identification of Giraffe Thorn, contact the herbarium in your state or territory.
Flower colour
Yellow
Growth form (weed type/habit)
Tree
Where it currently grows? Preferred habitat
Giraffe Thorn prefers open woodlands, grasslands and overgrazed pastures in semi-arid, tropical and subtropical environments (Navie 2004).
It is a long-lived plant that grows on sand in areas with an annual rainfall of less than 40 mm to 900 mm, and tolerates hot summer temperatures and severe frosts. In very dry areas it occurs along watercourses or where underground water is present. The taproot can descend to 60 m, providing access to deep ground water (Dlamini 2007).
Are there similar species?
Giraffe Thorn and Karroo Thorn (Acacia karroo) can be distinguished from all Australian native Acacias by the presence of both feathery foliage and sharp spines over 15 mm long. However, two other Acacia species found in Australia have these characteristics. Prickly Acacia (Vachellia nilotica) [as Acacia nilotica subsp. indica] is a native of India, has naturalised in tropical Queensland and parts of the Northern Territory and South Australia and is a Weed of National Significance. It has pods that are usually markedly constricted between the seeds, like a necklace. Mimosa Bush (Vachellia farnesiana) [as Acacia farnesiana] is widespread in northern Australia and is believed to have been introduced from Central America via the Philippines before European settlement. Its leaves have a gland on the leaf stalk before the first side branches of the leaf (Faithfull & Blood 2004).
Karroo Thorn (Vachellia karroo) [as Acacia karroo] is also a thorny plant with feathery leaves and has fluffy bright yellow flowers in small globular clusters in the leaf forks. The fruit of Karroo Thorn are larger and more elongated than the fruit of Giraffe Thorn. They are sickle-shaped or curved, smooth and hairless, have slight constrictions between the seeds, and turn dark brown as they mature (Navie 2004).
