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Brillantaisia lamium

Family

Acanthaceae

Botanical Name

Brillantaisia lamium (Nees) Benth.

Bentham, G. (1849) Niger Flora: 477. Type: Tropical Africa.

Common name

Brillantaisia

Weed

*

Stem

Flowers and fruits as a shrub about 1-2 m tall.

Leaves

Leaf blades about 5-14 x 3.5-8 cm, upper and lower surfaces clothed in hairs. Small pale glands usually visible on the underside close to the margin. Lateral veins about 10-12 on each side of the midrib. Petioles about 2-6 cm long, often narrowly winged towards the point of attachment with the leaf blade. Stems or twigs decidedly 4-angled usually with a line of hairs between the points of attachment of the petioles.

Flowers

Inflorescence a large terminal cymose panicle clothed in erect glandular hairs. Flowers about 30 mm long. Calyx lobes about 8-10 x 1 mm. Corolla about 25 mm long. Corolla 2-lipped, the upper lip 2-lobed, the lower lip 3-lobed. Stamens about 20 mm long, anthers about 6 mm long, deeply divided at the base. Ovary about 6 mm long, the base surrounded by a cup-like disk about 1-1.5 mm high. Style hairy, about 20-25 mm long. Stigma narrow, spoon-shaped, about 3 mm long.

Fruit

Fruits about 25-40 x 2-3 mm. Seeds flattened about 1.5-2 x 1.5 mm. Testa densely clothed in fleshy prostrate hairs arranged in groups.

Seedlings

Cotyledons +/- semiorbicular, about 8-10 x 13-16 mm, apex obtuse to emarginate, base truncate. Cotyledons +/- 3-veined but venation difficult to see. First pair of true leaves opposite, ovate, upper and lower surfaces clothed in hairs. midrib raised on the upper surface. Stem 4-angled. At the tenth leaf stage: leaf blade ovate to lanceolate, base attenuate, both the upper and lower surfaces clothed in hairs. Petioles about 30-40 mm long, upper half +/- winged. Stem distinctly 4-angled and glabrous except near the base of the petioles.

Distribution and Ecology

Appears to be a recently introduced species showing aggressive behavioural attributes. Originally from tropical Africa but now naturalized in a few places in NEQ. Altitudinal range no great, so far apparently confined to the coastal lowlands from near sea level to about 100 m. Grows in disturbed areas in rain forest and in agricultural waste areas Also naturalized on some Pacific islands.

Natural History

This species is a prohibited import into Western Australia. The fruits produce an essential oil. Ayedoun, M.A., et al. (1997) Journal of Essential Oil Research 9:605-607.

NEQ

X

Herb (herbaceous or woody, under 1 m tall)

X

Shrub (woody or herbaceous, 1-6 m tall)

X

RFK Code

3556