Manulea derustiana maybe

This white-flowering Manulea seen on the Minwater farm southwest Oudtshoorn may be Manulea derustiana, a range-restricted plant named for its nearest town, De Rust, east of Oudtshoorn.

The five, white, oblong petal lobes spreading around a small mouth in which yellow anthers are visible, do fit the species description. What doesn’t fit so well is the inflorescence structure in which all the flowers are not clustered head-like, but spaced raceme-like near the tip of the flower stem. Elongation of the compact M. derustiana raceme is expected during fruiting.

Leaves are unknown as far as the plant in picture is concerned. In M. derustiana, an annual herb, they are basal, long-stalked and glandular-haired. The blades are elliptic, double as long as they are wide and often with toothed margins.

M. derustiana grows in deep sandy soil in karoid scrub on south-facing slopes. The habitat population is considered vulnerable early in the twenty first century, due to habitat loss and degradation, as well as invasion by alien vegetation (Vlok and Schutte-Vlok, 2015; iNaturalist; https://www.worldfloraonline.org; http://redlist.sanbi.org).