Orobanche cumana

O. cumana produces leafless flowering stems 40-60 cm high bearing alternate scales less than 1 cm long. Although usually unbranched above ground, multiple stems sometimes arise from a single tubercle below ground. The plant is pale, completely lacking any chlorophyll. The base of the stem, below ground, is normally swollen and tuberous. The inflorescence, occupying up to half the length of the stems carries many acropetally developing flowers, arranged in spikes or racemes, each subtended by a bract 7-12 mm long (without the additional bracteoles present in O. ramosa). The calyx has four free segments, more-or-less bidentate, 7-12 mm long. The white corolla tube, 20-30 mm long, is inflated near the base, conspicuously down-curved, with narrow reflexed lips, up to 10 mm across. The tube is mainly white or pale while the lips are contrastingly blue or purple, without distinct venation. Filaments are inserted in the corolla tube, 4-6 mm above the base. Filaments and anthers hairy. A capsule develops up to 8-10 mm long and may contain several hundred seeds, each about 0.2 x 0.4 mm. A single plant carries 10-100 flowers and hence may produce over 100,000 seeds (Chater and Webb, 1972).