A New Subspecies of Albizia tanganyicensis from Kenya. (Notes on Mimosoideae: XII)

Abstract

In 1970 Mr. J. B. Gillett, at that time Botanist-in-Charge at the East African Herbarium, sent for an opinion a specimen of an Albizia collected in 1968 by Dr. F. R. Fosberg in the Meru National Park, Kenya. Careful examination and comparison indicated clearly that its closest affinity was with A. tanganyicensis Bak. f., at that time known from various stations in Tanzania and other territories southwards, but not at all from Kenya. The affinity was not immediately obvious as the Kenya plant showed major differences in its foliage. However, the only features to separate it from typical A. tanganyicensis were the smaller number of pinnae per leaf (about 2 pairs, as against 3-6), the fewer and often larger leaflets (3-4 pairs, as against (4-)713(-i 7)), and a grey (not a brown) pubescence on the outside of the corollalobes. The ultimate taxonomic status was left in abeyance pending the availability of further collections. These have gradually been made, the differences in the Kenya specimens have been maintained, and the time now seems appropriate to decide. The best verdict, in view of the nature of the differences, seems to be to make a new subspecies of Albizia tanganyicensis, and this is accordingly done. An additional reason for associating the Meru plant closely with A. tanganyicensis, and not separating it specifically, is the existence of a specimen S.R.Semsei 3416 (K), from Tanzania, Dodoma District, Imagi Forest Reserve, 18 Nov. I961. This specimen shows flowers and juvenile foliage, however the latter clearly with only 2 pairs of pinnae (on at least 6 leaves) and in this way similar to the Meru National Park plant, but with about 6-9 pairs of leaflets and in this way similar to typical A. tanganyicensis. The corolla-lobes are pale brown-pubescent outside. Semsei 3416 is thus an intermediate link between typical A. tanganyicensis and the Meru plant. Its status must remain in doubt until further work has been done in the field and it