Notes on East African Umbelliferae: Oenanthe, and a Genus New for Tanzania

Abstract

Summary. Oenanthe procumbens (Wolff) Norman and Oe. palustris (Chiov.) Norman are retained in Oenanthe in spite of the differences in fruit anatomy which caused Chiovenda to describe the genus Stephanorossia, here reduced to subgeneric rank, and the combination proposed. Afroligusticum elliotii (Engl.) Norman is recorded from Tanzania. Oenanthe being a rather troublesome genus in much of its range, some difficulties were anticipated in dealing with the African species, in spite of the fact that Norman (1932, 1933) had apparently tidied them up very nicely. In describing his Oe. uhligii Norman (1932) stated that: 'the ripe fruit of this species .... can best be described by comparing it with that of the widely spread and well-known Oe. stolonifera (Roxb.) DC., from which it is practically indistinguishable, both outwardly and in the cross-section . . . .' In view of this it was puzzling that when Norman (1933) discovered that Stephanorossia palustris Chiov. provided an earlier specific epithet for his Oe. uhligii, he made no comment on the very different fruit anatomy described by Chiovenda which caused the latter to place his new genus Stephanorossia in a completely different tribe of the Umbelliferae from Oenanthe. Norman simply stated in his second paper: 'I must confess that I am unable to see that Stephanorossia Chiov. differs in any way from Oenanthe L., as understood by, I believe, all recent writers'. Presumably Norman was so convinced of the correctness of his own observations that he merely assumed that Chiovenda's description was erroneous. Having previous experience of lapses on Chiovenda's part, I had every expectation when I came to investigate the matter that Norman's view would be justified. It is not. Chiovenda's observation of the characters which are important in this case-viz., the number of ribs on the fruit and the position of the vittae--was perfectly accurate, and Norman's was apparently faulty. The three African species of Oenanthe, all well-known, are Oe. mildbraedii Wolff, Oe. palustris (Chiov.) Norman and Oe. procumbens (Wolff) Norman. This last was described as a second species of Stephanorossia (elliotii) by J. J. Clark (1913), the type specimen being Scott Elliot 7791-which is also a syntype of Oenanthe procumbens and of Oe. ruwenzoriensis Norman (a synonym of procumbens). This implies that Clark believed (a) that Chiovenda's observations on Stephanorossia palustris Chiov. were correct, and (b) that the characters which Chiovenda described at a generic level were found also in Scott Elliot 7791. Clark, too, was quite correct. The fruit anatomy of the plants at present called Oenanthe procumbens and Oe. palustris is quite diverse from that found in Oe. mildbraedii, and that recorded in the literature for Oenanthe gener