The Trachyspermums of Socotra
Introduction
Socotra is a dry tropical island
of approximately 3625 km2 lying in the Indian Ocean (12° 30'N, 54°
00'E), E of Somalia and SE of the south coast of Yemen. The climate is
monsoonal with strong winds effectively isolating the island from the mainland
in the summer months. The long geological separation of Socotra from the
mainland, coupled with the powerful evolutionary pressures of its harsh
environment, have resulted in a fascinating flora of some 830 species,
over one third of which are endemic. The first botanical explorations were
made by Sir Isaac Bayley Balfour in 1880, and since then only a few collections
have been gathered from Socotra, or the small nearby islands of Abd al
Kuri, Samhah and Darsah which comprise the Socotran Archipelago. Since
1989 the Royal Botanic Garden, Edinburgh has mounted a series of major
botanical expeditions to the archipelago led by Anthony Miller. These have
greatly enhanced knowledge of the flora, as well as discovering novel taxa,
and assessing conservation status. This current paper is the result of
studies undertaken during the preparation of the Umbelliferae for the Flora
of Arabia, and the Ethnoflora of Socotra (Miller, Morris & Alexander
in prep.).
Authors
Mark
Watson, Edinburgh, U.K.
Emma
Barclay, Edinburgh, U.K.
Scheduling
Work complete.
Publications arising from this work
Barclay, E L. & Watson, M.F. (1998). A revision
of Carum and Trachyspermum (Umbelliferae) in the Socotran
Archipelago. Kew Bulletin 53(4): 897-907.
Herbarium collections of annual umbellifers from the Socotran Archipelago have been variously attributed to species in Carum (C. calcicolum Balf. f., C. kuriense Vierh., C. pimpinelloides Balf. f., and C. trichocarpum Vierh.), or the corresponding combinations in Trachyspermum. Recent gatherings have been examined alongside the historic material, using fruit anatomy, scanning electron microscopy and classical morphology. Results show that this endemic species complex should best be treated as one variable species Trachyspermum pimpinelloides (Balf. f.) H. Wolff.