Acanthaceae. Tribe Justicieae.
Crossandra, Salisb.; Benth. et Hook. f. Gen Plant. vol. ii. p. 1094.
Crossandra Greenstockii, S. Moore in Journ. Bot., 1880, p. 37; Fl. Cap. vol. v. sect. i. p. 37.
This plant is of interest as being one of the many outliers of the Tropical African flora in Southern Africa, and also as showing a connection between the floras of Eastern India and Tropical Africa. The genus Crossandra is represented by about 15 species, most of which occur in Tropical Africa, and one is recorded from India and the Malay States. The species figured here occurs in the Nyasa Highlands, and extends into Natal and the Transvaal as far south as Pretoria. During the month of October the plant may be found in flower in the neighbourhood of the Premier Mine, Pretoria, and the bright scarlet flowers form a conspicuous feature in the veld. Specimens have been recorded from various localities in the Northern Transvaal.
The fruits, as is so frequent in many species of Acanthaceae, have an explosive mechanism, i.e. they burst suddenly into two valves when wetted and scatter the seeds. The seeds, of which there are four in each fruit, are tightly enveloped with long hairs which straighten out and become mucilaginous when wet, thus fixing the seed to the ground.
Specimens are preserved in the National Herbarium, Pretoria (Herb. No. 1494).
Description:—An acaulescent plant with underground rootstocks. Stem short, glabrous. Leaves opposite, 5-11 cm. long, 2·2-5·2 cm. broad, obovate or elliptic, the narrower leaves sometimes lanceolate, obtuse, narrowed at the base, with the midrib and lateral veins prominent beneath, distinct above, glabrous or very sparsely pilose, especially on the midrib and veins. Peduncle 11-16 cm. long, terete, pilose, naked below, but with 2 opposite leaves above. Inflorescence 5-8 cm. long, 1·7-2·2 cm. in diameter, more or less 4-angled. Bracts 2·5 cm. long, 1·8 cm. broad, obovate, shortly aristate, with 4-7 long teeth on the margins, ciliate-glandular on both sides; bracteoles two, 2·5 cm. long, 2 mm. broad, linear, acuminate, acute, glandular. Sepals 5; the lateral sepals 5 mm. long, 1·5 mm. broad, linear, shortly aristate; remainder 9 mm. long, 2·5 mm. broad, oblong, subacuminate, ciliate above. Corolla-tube 2·2 cm. long, cylindric, ventricose at the base, inflated and glandular above; lobe 1·2 cm. long, 2·2 cm. broad, somewhat semicircular in outline. Anthers hairy. Ovary 1 cm. long, 3 mm. broad, oblong in outline, shortly beaked, glabrous; style threadlike; stigma inflated and hollow at the apex. Ovules 2 in each cell, discoid, covered with scales.