Witchweed – Striga

Stem is square in cross-section and 1-2.5 mm in diameter. Stems are branched or unbranched and branches can be above the ground or subterranean. Underground stems are round with scale-like leaves. Stems and leaves are sparsely covered with coarse, short, white, bulbous-based hairs. Leaves are mostly opposite on the lower half of the stem but irregular above, narrowly lanceolate, 1-8 cm long, up to 1 cm wide. Totally parasitic species have only small scale leaves and are pale-green or yellowish colour. Inflorescence is a terminal or axillary spike of sessile flowers, each flower subtended by a hairy bract up to 2 cm long. Calyx is tubular, up to 1 cm long, with 5-14 narrow lobes. Corolla is longer than calyx, asymmetrically campanulate, the tube up to 2 cm long. Corolla is 4-lobed, one lobe almost erect, the other lobes spreading horizontally, up to 2 cm across, pink, red, white, or yellow. Flower colour can be highly variable within a species. The stigma and stamens are hidden in the tube. The inflorescence may bear up to 100 flowers but only some are open at any one time. The capsules are up to 1 cm long and each develops several hundred minute seeds, approximately 0.3 mm x 0.2 mm.