These nearly white flowers photographed in October in the Harold Porter National Botanical Garden are probably Lobelia linearis. The commonly seen flower colour of this widespread Western Cape species is blue or purple, with only a small central patch on the corolla usually being white.
The many stems grow straight and erect from a tuft-like base, covered near the base in feathery to needle-like, divided leaves (Vlok and Schutte-Vlok, 2010; Manning, 2007).