light; moderate; hardy
Bright yellow; between November and June; spring summer autumn
sun; damp sun; semi-shade; clay soils; screen; shrubbery; container; wildlife bees insects
woodland forest; water; rocky places;
Subtropical East Coast; highveld
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The Yellow Shell-flower is a rare shrub (only 5 known population groups still existing in the wild) with a narrow distribution range along the mountainous border of north-west KZN and Mpumalanga. For those who know the area well, between Groenvlei, Wakkerstroom and Luneburg. Description: the Yellow Shell-flower is a gorgeous medium-sized shrub, usually forming multiple stems that grow straight and tree-like up to 3m, it is a neat and slender shrub for small gardens. Leaves are long and slender (40-7- x 7-11mm) and grow in whorls of 3 – 4. The olive green leaves are smooth or hairy with slightly raised conspicuous yellow veins on the underside, and margins are usually entire but when young, are often finely scalloped. Tiny glands cover the leaf surface, and these exude a faint lemon verbena scent when crushed, the only one of the South African species with this characteristic. The bright yellow flowers are typical of the ACROPHULARIACEAE family, large and pouch-like, with a narrow slit mouth, and they cover the foliage anytime between November and June. Between one and three flowers cluster on the leaf axils and are followed from February through May, by small brown fruits that split into two valves to release fine, dust-like seeds. The oil-collecting bee, Rediviva rufocincta, pollinates Bowkeria citrina; they use specialised setae on their forelegs to collect oil from the many oil-secreting hairs on the inner surface of the flower. Oil is then transferred to the hind legs and carried to the bee hive as larval food. Bowkeria citrina is easily propagated by 10 cm long cuttings; keep them moist until new green shoots appear. The natural habitats range from forest edges, along stream banks and on rocky hillsides and cliff edges on cool slopes, between 1400 and 1800 m. A rather slow growing shrub, it prefers cooler climates with plenty of rainfall. Both drought and the high coastal humidity will kill this species, and although enjoying partial shade at a forest edge, the Yellow Shell-flower thrives in full sunshine.