Flora Of Ethiopia Research Articles

A New Species of Portulaca from Kenya and Somalia

Summary. Portulaca decorticans sp. nov. is described as new. It is restricted to granitic outcrops in northern Kenya and southern Somalia. Portulaca can be divided very conveniently into species with non-articulated stems, usually alternate leaves and strictly axillary hairs and scales and those with articulated stems, strictly opposite leaves and with either a complete nodal whorl of hairs and scales (the stipules of many authors) or with no appendages. The latter group is, except for one aggressive weed, restricted to Australia and Africa plus those areas of Asia with well-known African affinities: tropical Arabia, southern India and Sri Lanka. It includes about 20 rather well-defined species that will be the subject of another account (Gilbert & West in prep.). The former group, found world-wide but with a major centre of diversity in the New World, poses much more intractable problems, even on a local, strictly African, scale. Both Peter (1932, 1938) and von Poellnitz (1934, 1940) worked extensively on the group and described a number of new species from Africa, mostly based on Tanzanian collections. Examination of all their types in Berlin, most of which survived the Second World War, and available herbarium material strongly suggests that a significant proportion of their taxa may well not merit recognition. It is also clear that there are further groups of specimens that might represent undescribed species. The variation is most complex in the area from central Kenya to central Tanzania and it is clear that the situation there can only be satisfactorily clarified by examining the genus in the field-herbarium material gives very little feel for the group because of the difficulty of dealing with often fragmentary specimens with very poorly preserved flowers. However there is one group of specimens from northern Kenya that stand out as representing a species quite distinct from anything described to date. As it is known from three separate localities on or very near to the border with Ethiopia, it must surely also occur in southern Ethiopia and should thus be mentioned in the account of the family for the Flora of Ethiopia. It is therefore formally described below.

A New Species of Centaurea L. (Compositae: Cardueae) from Ethiopia

Centaurea L. is a genus variously estimated to consist of from 450 (Mabberley 1987) to about 600 species (Airy Shaw 1973). It is centred around the Mediterranean region and the Near East with a few outliers in Northern Eurasia, North and East Africa, North America and Australia. Jeffrey (1968) revised the genus for tropical Africa and recognized nine species. One of these was given as C. sp. A and it was noted as being "... .an entity of uncertain status..." Jeffrey (loc. cit.) also suggested that it might represent an undescribed species and called for "...more and better material and field notes..." to clarify the identity of this taxon. In the course of the preparation of the family Compositae for the Flora of Ethiopia, the specimens cited under this taxon, as well as recent collections made from northern Ethiopia, were carefully examined. The material appears to represent an undescribed species of Centaurea and the following description is provided for it.

Six New Species of Euphorbia (Subgenus Esula) from Ethiopia

Recent Flora of Ethiopia collecting trips in southern Ethiopia have produced a wealth of material of Euphorbia including what appear to be a number of new species belonging to several distinct groups within the genus. The genus is almost certainly the largest within the Ethiopian Flora with 99 native species at the latest count. Several further species are recorded from just outside Ethiopia which, coupled with the apparent abundance of very local species within the Somali-Masai region of North East Africa, suggests that the final count will be substantially over 100. (Crotalaria (Leguminosae) with some 86 species (Thulin 1982) was hitherto thought to be the best represented genus in the Flora area). Five new species have already been described (Carter & Gilbert 1987; Gilbert & Carter 1984; Gilbert 1987). Gilbert (1987) gives an outline of the major divisions recognised by the author for the genus in Africa; all the species described here belong to subgenus Esula. Subgenus Esula is the largest in the genus and includes a number of sections that are sometimes themselves treated as subgenera (e.g. Carter 1988). This includes Trichadenia and Lyciopsis referred to here. The author has chosen not to follow such a course because it would detract from the more important divisions between the subgenera that are recognised. The new species are all known only from very restricted areas, in some cases single collections, but they are so distinctive and/or belong to relatively well known groups that it seems justified to give them formal names. A number of succulent species belonging to subgenus Euphorbia remain to be described.

A New Species of Echinops (Compositae, Cardueae) from East Africa

Jeffrey (1968) revised the genus Echinops, as well as a number of other genera within the Cardueae (syn. Cynareae) found in tropical Africa, and provided a key to 20 species, one of which was given as E. sp. A. Two specimens from Tanzania were cited under this name. Jeffrey (I.c.) wrote then that "these specimens probably represent an undescribed species allied to E. aberdaricus R. E. Fries", and stated also that the status of these specimens "... may be definitely determined" when more material is collected. The tropical African species of Echinops were later studied in connection with studies on the Compositae flora of Ethiopia, and a revision of the genus as occurring in Ethiopia was also attempted (Mesfin T. 1988). During this time the specimens referred to as E. sp. A. as well as a number of other recent collections were more closely studied. It has therefore become possible to determine the status of these East African specimens and provide a description for a new and apparently widespread but little-collected species from the southern highlands of Tanzania and Mt Elgon in Uganda and Kenya.

The Genus Poa (Gramineae) in Ethiopia

Summary. Nine species of Poa are recognized in Ethiopia. Their variation and interrelationships are discussed and a key and descriptions are provided. The new Ethiopian endemic species P. hedbergii S. M. Phillips is described. Poa is one of the largest genera in the Gramineae, with about five hundred species in temperate and cold regions of the World. It extends to mountains in the tropics, including the uplands of Ethiopia at altitudes mainly above 2000 m. Poa is a genus of notorious taxonomic difficulty, the uniformity of structure of its spikelets being coupled with the great variability of those few characters on which the taxonomist could have hoped to rely, leading to difficulties almost unparalleled in the family in the delimitation of species. This variability arises largely through extensive introgression, polyploidy and sometimes subsequent apomixis (Nygren 1954). The necessity of writing an account of Poa for the 'Flora of Ethiopia' brought about the present study, and it immediately became apparent that the Ethiopian species are no exception to the problems which pervade the genus elsewhere in the world. These difficulties in Ethiopia are compounded by the fact that most species are still very poorly represented in herbaria, owing to the remoteness and inaccessibility of the high mountains where they grow. Indeed, of the nine species listed here, only P. leptoclada and P. schimperiana are at all well collected, these being the only two which occur widely at altitudes below 3500 m. In a genus where the assessment of infraspecific variability is so important for an understanding of which characters might be used for delimiting species, it is obvious that caution is required when only a few specimens are to hand. Recent studies of the genus, e.g. Tateoka on Japanese Poa (1985), Edgar on New Zealand Poa (1986) and Vickery on the Australian species (1970) have relied on extensive field work and the examination of large numbers of herbarium specimens. There is no doubt that such a broad approach, including cytogenetic studies, is the only way in which we can hope to understand the inherent variability of this genus. Unfortunately, such a combined approach is impracticable for the Ethiopian species as not only do they grow in remote areas, as already mentioned, but are of very little economic importance for the country, so would hardly justify at present the large expenditure of time and effort involved. However, taxonomic groundwork based on herbarium specimens still remains the basis for further studies, so the aim of this paper is to present as complete a taxonomic treatment as the few available specimens will allow. It should be regarded as a first approximation only, and it is confidently expected that the number of species present will rise as more material is collected. The wide range of infraspecific variability accepted here in characters such as ligule length and lemma hairiness and size, when compared with the many fine characters used to

Two New Species of Polycarpaea (Caryophyllaceae) from Somalia

For some years now, material of some very striking cushion-forming plants has been accumulating at the end of the Caryophyllaceae, in both the Kew Herbarium and the East African Herbarium in Nairobi, in folders marked '?gen. nov.?'. These have much-branched woody stems covered with subulate leaves and with tiny pedunculate inflorescences. They were re-examined in the course of preparing an account of the Caryophyllaceae for the Flora of Ethiopia and it became clear that they had many features in common with some species of Polycarpaea, most notably P. spicata Wight ex Arn. and the very remarkable Limonium-like P. kuriensis Wagner, known only from the island of Abd al Kuri near Socotra.

New and Interesting Species of Euphorbiaceae from Ethiopia

Summary. The following notes on new and interesting species of Euphorbiaceae (other than Euphorbieae) arise from the preparation of an account of the family for the forthcoming Flora of Ethiopia. Eight species are described as new: Andrachne ephemera, Phyllanthus borenensis, P. dewildiorum, P. mooneyi, P. oblongiglans, Acalypha marissima, Erythrococca uniflora and Cephalocroton incanum. 1. Andrachne L. (1753). A. ephemera M. Gilbert sp. nov. ab Andrachne aspera Spreng. habitu ephemero, floribus minoribus, sepalis masculis quam petalis duplo longioribus, ovario glandibus nigricipitibus differt. Typus: Ethiopia, Friis, Mesfin & Vollesen 3157 (holotypus K; isotypi C, ETH, UPS). Erect sparsely branched ephemeral to 20 cm high, usually less; stems pubescent. Leaves alternate, diminishing in size towards apex; petiole up to 10 mm long; lamina broadly ovate to reniform, up to 11-13 x 11-15 mm, base truncate to slightly cordate, apex rounded to very shallowly emarginate, glabrous except for sparsely glandular pubescent margins; stipules ovate, c. 0-6 x 0.4 mm, margins glandular-denticulate. Monoecious, flowers 5-merous, solitary, present in all but lowermost leaf-axils. Male flowers: pedicels up to 1-5 mm; sepals oblong-ovate, c. 1 mm long, entire, greenish with pale margins, glabrous; petals narrowly oblong-lanceolate up to half as long as sepals, sometimes apparently absent; disc glands free, rough; stamens 5, free, filaments c. 0-4 mm, anthers 0-2 x 0-2 mm. Female flowers: pedicels c. 2 mm, extending slightly to 2-5 mm in fruit; sepals oblong-lanceolate, 1-3 x 0-5 mm, green with narrow white margins, glabrous, accrescent to 2 mm long in fruit; disc glands minute, clavate; ovary depressed globose, 0-6 mm diam., glandular-pubescent with the hairs soon developing conspicuous black heads, styles c. 0-6 mm long, bifid to base. Regma globose, c. 3 mm diam., pale brown, rather papery, obscurely reticulately veined, with conspicuous black-tipped hairs. Seeds segmentiform, 1-7 mm long, pale brown densely covered with whitish pustules. Fig. 1A-G.

Agrostis kilimandscharica (Gramineae) and Its Allies in Eastern Africa

While preparing an account of the genus Agrostis for the 'Flora of Ethiopia', I discovered several anomalous specimens from the Ethiopian highlands, either undetermined specifically or referred provisionally to the East African species A. kilimandscharica Mez and the West African species A. mannii (Hook.f.) Stapf. A preliminary investigation of these 2 species showed them to be extremely variable, not only vegetatively (probably at least partially in response to environmental factors), but also in spikelet characteristics, with the specific boundaries far from well defined. In order to determine the correct identity of the Ethiopian collections, it was therefore necessary to undertake a detailed study of variation within this group of Agrostis. A. kilimandscharica and A. mannii are extremely closely related, and are referred to in the 'Flora of Tropical East Africa' as being only 'barely distinct'. A third species, A. producta Pilg. from East Africa, also falls within this group, the three species forming a closely knit species-complex. The group as a whole is characterized by the possession of a loosely tufted habit, linear flat leaves, loose flexuous panicle, and spikelets with a sub-basally awned, hairy lemma. All three species are upland plants, occurring only on mountains over 2000 m. A. mannii is mainly confined to the highlands of West Africa (Cameroon and Fernando Po), but the centre of distribution and variation for this group is the highlands of East Africa. Only A. producta extends southwards beyond the mountains of northern Tanzania, occurring on the high ground of Mbeya and in Malawi. These are grasses of the montane forest belt, and the grass and scrubland above to about 3500 m. A. kilimandscharica is particularly frequent in clearings in bamboo forest and in ericaceous scrubland, and only on Mt Kenya does it penetrate upwards into the lower levels of the alpine moorland belt (above 3500 m). At the lower extreme, A. kilimandscharica also occurs in central Kenya below the present level of the montane forest in the area extending from Mt Kenya and the Aberdares towards the Cherangani Hills and Mt Elgon. However, Hedberg (Biol. J. Linn. Soc. 1: 140 (1969)) has shown that these areas linking the higher ground in Kenya are climatically suited to montane forest, which indeed once covered this area, but has been progressively cleared by man for agriculture. Presumably populations of A. kilimandscharica from these areas have been able to persist in the secondary habitats which have arisen since the montane forest was cleared.

Aethiocarpa (Sterculiaceae-Dombeyeae), a New Genus from Somalia

While working on Triumfetta for the Flora of Ethiopia, I came across some collections of what was presumed to be a new species of this genus. They showed several characters which are quite exceptional in Triumfetta (solitary flowers, pedicels with three bracteoles, small entire emarginate leaves, lepidote indumentum covering all parts). The sheets had obviously been placed here because of the fruit, which superficially is remarkably like the fruit of some species of Triumfetta from the same area (e.g. T. actinocarpa S. Moore and T. trigona Sprague & Hutch.). Examination of the flowers, however, revealed that the plant has the stamens in groups of three alternating with large linear staminodes, and that it therefore rightly belongs in Sterculiaceae. The similarity in the fruit also proves at closer examination to be merely superficial. While Triumfetta has a 5-locular ovary with 2 ovules per locule, this plant has a 1-locular ovary with a single basal ovule. Searches in the herbarium and in the literature have failed to find any described plant matching it, and it is consequently described as new.

A New Species of Corchorus (Tiliaceae) from East Africa

During recent field work the following new species of Corchorus was collected in S Ethiopia. After having recently written an account of the genus for the Flora of Ethiopia, I immediately realized that this was a new record for the Flora. Subsequent studies in the herbarium and library at Kew have convinced me that the plant cannot be matched with any previously described species. During examination of E African material a second collection of what is clearly the same species was found amongst unnamed material from Tanzania.

The Sida cuneifolia-Complex (Malvaceae) in Africa

Summary. The Sida cuneifolia-complex-usually considered to consist of a single widespread species only-is shown to consist of six distinct species: S. cuneifolia Roxb. endemic to India and five species in Africa. Four of the African species are without validly published names and are described here: S. massaica, S. tanaensis, S. shinyangensis and S. tenuicarpa. Sida schimperiana A. Rich. (1847) was described from a Schimper-collection from Ethiopia. For the next 100 years this name was used for all African material belonging to this complex. Clement (1957)-while working on N American Sida commented upon the similarity between S. schimperiana and S. cuneifolia Roxb., an Indian species described in 1832. Clement considered the two to be the same species, a view which has since then been generally accepted by botanists working on African floras-Cufodontis (1959), Hauman (1963), Agnew (1974). My interest in this group stems from my work with Malvaceae for the Flora of Ethiopia. It soon became clear that the Ethiopian material of 'S. cuneifolia' could be divided into two quite distinct taxa with no intermediate collections whatsoever. Examination of East African material showed that both Ethiopian taxa were widespread in Kenya and northern Tanzania, but also revealed here three further taxa all considerably more restricted in their distribution. All these five taxa are separable by differences in structure and sculpturing of the mericarps as well as by differences in indumentum and flower-size, and I see no reason not to consider them as distinct species. Comparison of these species with the true S. cuneifolia from India shows this to be another quite distinct species which is not identical with any of those from Africa. (Fig. 1.) The group is well-defined within Sida. The species are small shrubs or shrubby herbs with cuneate to obovate leaves with a notched apex with a central tooth (extension of the midrib). The leaves are otherwise entire or have a few apical teeth (Fig. 1). The flowers are subsessile or shortly pedicelled, solitary in the leaf-axils and usually also congested into terminal heads. The corolla is pale yellow to orange, often with reddish veins. The fruit consists of five mericarps.

Variation in Macaranga capensis (Euphorbiaceae)

Our interest in Macaranga originates from a study of afromontane trees (IF) and preparation of an account for the Flora of Ethiopia (MGG). This brought to our attention the problem of delineating M. kilimandscharica from M. capensis. Ethiopian material is relatively uniform and matches M. kilimandscharica but Radcliffe-Smith (in Kew Bull. 37: 423, 1982) had recorded M. capensis from S Ethiopia. Thus we made a special study of Macaranga whilst in Ethiopia in 1984. It was clear that the collection in question, Chafey 163, was a juvenile shoot of M. kilimandscharica in the traditional sense. We subsequently studied all Kew material of the two taxa. The cordate, densely hairy leaves of M. capensis against the round-based, subglabrous, often glaucous leaves of M. kilimandscharica do in fact correlate with the difference between juvenile and adult shoots of the latter. Thus M. capensis can be regarded as a neotenous form and sterile material, in which it is not possible to tell the maturity of the plant, and juvenile shoots of M. kilimandscharica cannot be reliably named. Even with flowering material, the placement of some collections seems arbitrary. Together the two taxa range from S Natal to Ethiopia; the region of overlap between good examples of them extends from Malawi, the southern limit of typical M. kilimandscharica, to Kenya, the northern limit of typical M. capensis. It seems clear to us that it is impossible to keep up two distinct species. The apparent lack of any clear-cut spatial separation argues against recognition of subspecies though a name is available at this rank. As the two extremes are quite distinct, it seems to us most useful to treat them as varieties, and the necessary new combination is made.

A New Subspecies of Uvaria (Annonaceae) from Ethiopia and Kenya

Since my account of the East African Annonaceae (Fl. Trop. E. Africa: Annonaceae (1971)) a number of taxa left undescribed have been recollected more adequately and a certain number of generic changes are also necessary. Some of the new taxa have been dealt with by K. Vollesen (Bot. Notiser 133: 53-62 & 403-404 (1980)) but several others will form the basis of a separate paper. A request for an account of the few taxa which occur in the area covered by the Flora of Ethiopia has, however, rendered necessary the prompt description of the taxon described here.

Notes on Balanites from the Somali Republic and Ethiopia

A study of the genus Balanites, which is currently being completed, has resulted in the recognition of several new infraspecific taxa. It is intended that a full revision of the genus will be published shortly, but because of the need to provide an account of Balanites for the Flora of Ethiopia before the revision becomes available, the following new variety and subspecies which occur in Ethiopia are briefly published here. Justification for their recognition will be given in the detailed treatment appearing later.

Name Changes for Well Known Species of Boehmeria (Urticaceae)

Summary. Preparation of an account of the Urticaceae for the Flore des Mascareignes and preparatory work on the family for the Flora of Tropical East Africa and the Flora of Ethiopia has brought to light two unfortunate changes of names in the genus Boehmeria-not merely changes, but a switch of name: B. macrophylla has to be removed from one well-known species and applied to one even more widely known. The Himalayan species long known as B. macrophylla D. Don (1825) requires a new name since there exists the older B. macrophylla Hornem. (1815). The new name for this species, which is naturalised on La Reunion and Mauritius in the Mascarenes, will shortly be published by D. G. Long (of Edinburgh) who is working on the Flora of Bhutan. B. macrophylla Hornem. turns out to be the oldest name for the Asiatic and African species previously known as B. platyphylla D. Don (1825). It appears from Hornemann's protologue (Hornemann (1815)) that his B. macrophylla was introduced to the Copenhagen Botanical Garden in 1810. The country of origin is not indicated, and we have been unable to find additional information from the Garden's archives. As Hornemann usually states the country of origin as accurately as possible, it seems likely that the material came from another botanical garden. A specimen ofB. macrophylla was preserved in 1813 and is still at C, annotated in what could be Hornemann's own hand. The specimen has been compared with material at Kew, and its identity with B. platyphylla D. Don confirmed. B. platyphylla is a very widespread and variable species, in our opinion distributed from West Africa to Indo-China. The eastern limit is not easily established, but it is certain that Weddell (1869) was wrong in including the following earlier taxa from China, Japan and Polynesia in B. platyphylla: B. spicata (Thunb.) Thunb., B. japonica (L.f.) Miq., and B. virgata (G. Forst.) Guillem. Two other early names are relevant here: Urtica caudata Burm.f. (1768) and Urtica macrophylla Thunb. (1784). U. caudata Burm.f. is described from Java and is probably conspecific with B. macrophylla Hornem., but a combination based on this basionym would not be permissible in Boehmeria because of the existence of B. caudata Swartz (1788). Urtica macrophylla Thunb. is also a Boehmeria, although in our opinion distinct from B. platyphylla D. Don. Neither Hornemann nor D. Don makes any reference to U. macrophylla

Novitates pteridologicae aethiopicae

Summary The pteridological flora of Ethiopia, Somalia and Socotra amounts to over 180 species. These novitates consist of three new species (Asplenium erythraeum, Asplenium smedsii and Asplenium stipicellatum), forty-three records of species not yet known from the area of the Adumbratio Florae Aethiopicae and a new record of a rare species already collected in another locality of Ethiopia. The forty-seven species belong to thirty-three different genera of the Pteridophyta, nineteen of which are now recorded for the first time from Ethiopia. The majority of the species come from the southwestern region of Ethiopia, particularly from Kaffa, which has a very rich pteridological flora. The occurrence of these species in the southern mountains of Ethiopia, and not in the northern ones, but present in the Kenya-Uganda highlands, strengthens the views of those phytogeographers who maintain that the montane flora of southern Ethiopia has a closer affinity with that of the Kenya-Uganda highlands rather than with t...