Compilation
Saintpaulia rupicola

USES. Cultivated as an ornamental, though not as widely as subsp. ionantha. CONSERVATION This subspecies is restricted to a very few sites in coastal Kenya. The Mwachi population is believed to be extinct (S.A. Robertson, pers. comm.) and there has been continued tree cover loss and habitat degradation in the remaining sites (Eastwood et al. in Bot. Mag. 15: 56(1998)). The current populations may not regenerate due to lack of suitable habitat (S. Simiyu, pers. comm.). It is therefore currently considered Endangered (EN B1ab(iii)+2ab(iii)) but may qualify as Critically Endangered under different criteria following more complete assessment of the populations. Subsp. rupicola is unusual in growing (or at least persisting) on rather exposed limestone outcrops where it is likely to experience periodic drought; indeed the plants are often associated with a variety of succulents and other drought-tolerant taxa. Such plants have developed long fleshy petioles, large thick leaves and stout fleshy stems, all of which may be an adaptation to this environment. However, it is notable that cultivated plants derived from these populations retain these characters. Plants collected from deeper shade, at the Mwachi Forest Reserve (Robertson & Luke 6248!) and Sokoke Forest (Campbell ,cult., R.B.G. Kew) have smaller leaves and shorter petioles. Specimens from the isolated population at Kacharoroni gorge have previously been considered a separate species, collectors having pointed principally to the large size of these plants. The more vigorous growth habit is possibly a response to high soil nutrient content due to the abundance of guano from the associated bat colony (S.A. Robertson, ms.). Furthermore, similarly robust plants have been collected from the colony of S. rupicola at Cha Simba to the south (Robertson 5461!). The Kacharoroni plants certainly have longer hairs throughout, a character linking this population with those from the Mwachi and Sokoke forests. These latter colonies have more elliptic leaves than typical in the subspecies. However, these variations in leaf shape and indumentum appear insignificant when compared to the variability recorded within the S. ionantha complex as a whole; they are therefore treated here as a single entity. The plants with a pilose indumentum provide a clear link between subsp. rupicola andsubsp. ionantha var. ionantha. Although they are usually readily separable by the differing capsules (those of the coastal plants in the ionantha complex being much shorter and more ovoid), there is a slight overlap at the extremes of the range in fruit sizes. Plants from the Pangani Falls, Tanga District (Simiyu et al. H56!), appear rather intermediate between the two taxa. Genetic data (e.g. Linqvist & Albert in Syst. Geogr. Pl. 71: 40 (2001)) also indicates that the rupicola group is phylogenetically embedded within the ionantha complex; it is thus reduced to subspecific status here.