Mesfin Tadesse

An account of Bidens (Compositae: Heliantheae) for Africa.

Monographs of Coreopsis L. and Bidens L. were published by E. E. Sherff in 1936 and 1937, respectively. Characters and character states used since the time of Linnaeus (1753) to differentiate between these taxa were evaluated in these works. Difficulties in the assignment of taxa from South America and the Pacific Islands to one or the other genus were expressed while the African species were regarded as presenting little or no difficulty. In some cases, however (Sherff 1937: 544545), close resemblances between taxa within these genera were portrayed, e.g. Bidens steppia (Steetz) Sherff was compared with Coreopsis oligoflora Klatt (= Bidens oligoflora (Klatt) Wild). Later studies on African members of Coreopsis L. and Bidens L. (e.g. Wild 1967; Cufodontis 1967; Agnew 1974; Wickens 1976; Mesfin 1984, 1986) indicated that the characters used in separating them are too variable even within a single species. In connection with his studies on Polynesian taxa, Gillett (1975) discussed the taxonomic difficulties caused by the presumed differential characters between Bidens and Coreopsis. A revision of the genus Bidens for NE Tropical Africa was presented by Mesfin (1984a) wherein all taxa from this region which were previously kept in Coreopsis L. were transferred to Bidens L. In a subsequent paper (Mesfin 1986), the morphological basis for the inclusion of African species of Coreopsis L. in Bidens L. was given. The present work is the culmination of the study begun in 1980. It is an attempt towards the presentation of a fuller account of the genus Bidens L. for Africa incorporating into it all taxa that have hitherto been treated within Coreopsis L. For taxa that have recently been revised (cf. Mesfin 1984a, 1984b, 1986) only the revised list of synonymy, the pattern of distribution and the habitat are provided. Only a few selected specimens are provided for each taxon. A separate list of examined specimens is deposited at EA, ETH, K and UPS.

A Revision of the Genus Echinops (Compositae-Cardueae) in Tropical Africa

The most recent revision of tropical African species of Echinops was that made by Jeffrey (1968) who provided a key to the 20 species then known. Since then a number of new species have been described and there has also been some relegation of taxa (Lisowski 1989, Mesfin 1990, Mesfin & Berhanu 1990). The species found in Ethiopia were revised in 1990 (Mesfin & Berhanu 1990). In this work, notes on the phytogeography of the genus in Africa were also presented. The only descriptions then available for many of the remaining species were the original ones. It was thus thought prudent to thoroughly revise the African members of the genus and provide English descriptions for all of them. The African species have also been the subject of chemical studies (Berhanu et al. 1991). The investigation of the roots of nine species of Echinops from Ethiopia revealed the presence of 20 polyacetylenic thiophenes, sesquiterpenes and triterpenes. In this work the presence of three groups of species was indicated and a call made for studies on those species with tuberous roots from other parts of tropical Africa. The morphological study is based on herbarium specimens kept at BM, BR, EA, ETH, K, LE, MO, NY, P, UPS, US, W and WU, and also on field observations in Ethiopia and Kenya. All types studied are indicated (!).

New Species of Vernonia (Compositae-Vernonieae) from Northeast Africa

The checklist of plants for Northeast Africa prepared by G. Cufodontis (1952 1974) is the basis for all revisionary work on the Spermatophytes of this region. In 1966, Cufodontis recorded 66 species of Vernonia. A number of these have since been reduced to synonymy (Jeffrey 1988). In his account of the Vernonieae in East Tropical Africa, Jeffrey (1988) indicated that 25 of the 126 species listed also occur in Ethiopia, and 4 species in Somalia. A total of 55 species is currently recorded for the two countries.

New Species of Iphiona and Pentanema (Compositae: Inuleae) from Somalia with a Note on P. indicum (L.) Ling in Africa

Iphiona pinnatifida and Pentanema ligneum are described as new species from Somalia; both species are illustrated. I. pinnatifida is compared with I. phillipsiae (S. Moore) A. Anderb., the only other species known from Somalia and also with I. anthemidifolia (Bak.) A. Anderb., a species endemic to the coast of Yemen (Hadramut: Mukalla and Ras Fartak). Pentanema, with its centre of diversity being in South-Central Asia, is represented in Africa by two species. P. indicum (L.) Ling, a well known species from Asia, known by a variety of names in Africa, is shown to be a widespread introduced weed; Vicoa leptoclada (Webb) Dandy is placed in its synonymy.

A new species of Pluchea (Compositae.: Plucheeae) from Somalia

In the course of preparation of the account of Plucheeae (Compositae) for the Flora of Ethiopia, species such as Pluchea pteroclada Chiov. and P. pectinata F. G. Davies & J. P. Lebrun, both abundant in Somalia, were found to be represented by one or a few herbarium specimens each from the Ogaden region, and southern Sidamo in Ethiopia, respectively. Extension of the study of specimens of Pluchea from Somalia at the herbaria in Nairobi (EA) and at Kew (K) revealed an undescribed but distinctive species with fleshy leaves. This species is here described and illustrated. Pluchea succulenta Mesfin, sp. nov. P. aromaticae Balf. f. similis sed foliis oblanceolatis sessilibus (non anguste ellipticis petiolatis) distinguitur; a P. heterophylla Vatke foliis oblanceolatis marginibus integris, foliorum paginis et phyllariis dense sessilio-glandulosis (non foliis obovato-oblongis, integris vel inciso-dentatis, foliorum paginis lepidoso-punctatis, ramis phyllariisque dense stipitato-glandulosis) differt. Typus: Somalia, E. Mijertein, Hafun Peninsula, 14 Nov. 1959, Hemming 1831 (holotypus EA; isotypus K). Bushy perennial herb or straggling shrub, up to 40 cm high; stem woody below, densely covered with marscecent leaves or with evident scars of leaf bases. Leaves simple, alternate or spiral and closely spaced on short internodes especially on young branches, oblanceolate, narrowed into the sessile base, succulent to sub-succulent, glabrous but with dense shiny resinous glands, 2-4-5 x 0 -5-1 -2 cm, margins entire. Capitula heterogamous, disciform, 8-10 x 6-12 mm, hemispherical, solitary and terminal or few, corymbosely arranged; peduncle up to 5 cm long, bracteate, densely sessile-glandular. Phyllaries 7-9-seriate, closely imbricate, continuous with bracts on peduncle, densely sessile-glandular, narrowly ovate with acute or acuminate apices, margins ciliate or shortly but regularly fimbriate; outer 2 - 2 - 5 x 0 - 6 -0-8 mm; inner 5-6 x 0-5-0-7 mm. Receptacle flat or slightly depressed in middle, epaleate. Corollas purple or mauve-pink. Outer florets female, 4- 5-seriate; corolla filiform, 5 - 2

A New Species of Chiliocephalum Benth. (Compositae: Inuleae) from Ethiopia

Chiliocephalum Benth. (1873a) has until now been considered as a monotypic genus (Oliver 1877: 337; Cufodontis 1966: 1104; Anderberg 1988: 1) consisting of C. schimperi Benth. (1873b). During the course of studies on the Compositae for the Flora of Ethiopia, a second species of the genus was discovered among the recently collected material in the herbaria in Ethiopia (ETH) and Kew (K). Field studies at one of the localities from which the species was reported were made in 1986.