SUBDIVISION OF PELARGONIUM SECT CORTUSINA (GERANIACEAE)

The sect. Cortusina (Dc.) HARV. s.l. is divided into the sectt. Cortusina (Dc.) HARV. s. str. and Reniformia (KNUTH) DREYER, comb. nov., P. cortusifolium L'HERIT., P. crassicaule L'HERIT., P. echinatum CURT., P. magenteum J. J. A. VAN DER WALT, and P. sibthorpifolium HARV. remain in the sect. Cortusina s. str., while the species P. album J. J. A. VAN DER WALT, P. dichondrifolium Dc., P. odoratissimum (L.) L'HERIT., P. reniforme CURT., and P. sidoides Dc. are removed from the sect. Cortusina s.l. and included in the revised sect. Reniformia. Both sections are well characterized by morphological, anatomical, karyological and palynological features. The chromosomes of Cortusina s. str. are small and based upon x = 11; those of Reniformia are larger and based upon x = 8. The size and surface sculpture of the pollen grains differ markedly between the two sections. Flavones and hydrolysable tannins occur in sect. Reniformia, but are absent in sect. Cortusina s. str. After hydrolysis hydroxybenzoic acids, which are present in large amounts in Reniformia, occur only in traces in Cortusina. The two sections also occupy distinctly different geographical areas. A close relationship between sect. Reniformia and some species of sect. Ligularia (SWEET) HARV. is indicated by the occurrence of artificial hybrids.