Solanum (Solanaceae) in Uganda

Of the 41 species, subspecies and cultivar groups in the genus Solanum L. (Solanaceae) that occur in Uganda, about 30 are indigenous. In Uganda several members o f the genus are utilised as food crops while others are put to medicinal and ornamental use. Some members are notorious weeds. A key to the species and descriptions of all Solanum species occurring in Uganda are provided.

The genus Solarium L. belongs to the family Solanaceae, and contains about 2 000 species of which about 35 occur in Uganda. Several species are important food crops, yielding edible fruits and leaves whereas others are ornamentals or weeds (Heine 1963).
The genus also contains plants of medicinal value. For example the fruits of S. anguivi Lam. contain alkaloids used in the treatment of a number of diseases including chronic respiratory diseases (Bector et al. 1971). Walters (1965) observed that Solarium alkaloids have antifungal effects. Thus it is possible that some of these alkaloids could be used as antibiotics. Beaman-Mbaya & Muhammed (1976) reported that alkaloids from fruits of S. incanum L. are used in treatment of cutaneous mycotic infections and other pathological conditions in Kenya. In Uganda, the soup from green fruits of S. anguivi Lam. is popular especially among women, for it is believed to cure hypertension (Sengendo 1982).
The genus is widely distributed throughout the world with major species representation in America, Australia and Africa. The genus was first studied by Dillenius (1732) and later by Linnaeus (1753). Since 1753 the genus has been reclassified innumerable times and a multitude of varieties, subspecies and species have been named, especially in the section Solanum. For example, Dunal (1813) in his monograph of the genus, described 60 species belonging to section Solanum. Bitter (1912Bitter ( , 1913Bitter ( , 1917Bitter ( , 1919Bitter ( , 1921Bitter ( , 1922Bitter ( , 1923 was the second worker to attempt to monograph the genus: he is criticized for being 'more of a splitter than Dunal, and he described more than 60 new Solanum species from the Americas alone' (Edmonds 1977). He recognised 20 sections for the genus, and revised Solanum in Africa utilizing mainly collections from German expeditions. He erected a partial classifica tion of Solanum.
The validity of some of Bitter's varieties has been questioned because they were based on minor variations which are of very limited taxonomic value. However, his work is the most detailed treatment so far available on African Solanum. D'Arcy (1972) provided a modem classification of the genus Solanum into subgenera, sections and series and his classification is widely accepted today. It is also followed here.
Although the above major works and others attempted to streamline the taxonomy of Solanum, the genus is taxonomically difficult, due to various factors. These in clude the difficulty of associating the names of Solanum used by earlier taxonomists with plants of today due to early descriptions being brief, often vague and frequently lacking in characters now considered to be diagnostic. Another problem is that some of the early names, for ex ample many of the names of Linnaeus and those before him, are difficult to typify (Hepper 1979).
Another problem is the occurrence of polyploid series within the section Solanum (Edmonds 1977), such as tetraploids and hexaploids occurring within the S. nigrum complex. These may provide a barrier to hybridization between morphologically similar plants leading to cytoraces which are difficult to differentiate using classical methods.
There is also considerable phenotypic plasticity within species and hybridization between closely related species. Hybridization followed by inbreeding may result in for mation of new populations different from either parent. This is particularly true for the cultivated species, as for example found in sections Melongena and Oliganthes. A large number of 'microspecies' or 'semispecies' (Grant 1971) occur in section Solanum and it is difficult to decide which of these deserve taxonomic recognition.
In recent years, there has been an explosion of data from various taxonomic research projects aimed at at tempting to solve some of the above problems and im proving the know ledge of the genus. The majority of these studies has been made outside Africa. Jaeger (1985) recognized 80 species of Solanum in Africa. To a large extent we accept the taxonomic treatment of the taxa he discussed. The information in this work, especially on typification and synonymy, was very useful in the present study. No comprehensive taxonomic study had been made on the genus in Uganda. Lind & Tallantire (1975) provided short descriptions of only three Ugandan species of Solanum, i.e. S. terminate Forssk., S. incanum L. and S. nigrum L. Sengendo (1982) produced some data on the two species S. anguivi and S. aethiopicum L., while Bukenya (1991) gave a comparative account of a few Solanum fruit and leaf vegetables.
To date the Solanaceae has not yet been treated for the Flora o f tropical East Africa. Hence, to identify a species of Solanum in Uganda one has to use other regional floras, particularly the Flora o f tropical West Africa, edn 2 (Heine 1963). However in this Flora, not all the species of Solanum occurring in Uganda are included and the descriptions of species are brief.
It was necessary to carry out a comprehensive study of these species so that critical descriptions and a key to the species could be provided.

MATERIALS AND METHODS
The species descriptions were largely based on the study of herbarium material in the Botany Department. Makerere University; the Royal Botanic Gardens, Kew; the Forest Herbarium. Oxford, and the Institute of Sys tematic Botany. Munich.   The genus is recognized by the 5-partite calyx and by long, often connivent anthers dehiscing by terminal pores and with short filaments. Other characters useful for recognition are the frequently rotate, 5-lobed corolla, the fruit being a berry with flattened seeds; the often stellatepubescent prickles; and the often extra-axillary, usually cymose inflorescence.
Leaxes subentire or shallowly lobed, often mem branaceous; indumentum simple, hairs rarely branching. Prickles absent. Flowers mostly small. Corolla mostly deep ly lobed. Filaments often pubescent; anthers short, dehiscing introrsely by large, often oblique terminal pores and some times ultimately by longitudinal slits in the upper portion. Chary glabrous. Fruit rather small, 7-15 mm diam.
The subgenus is represented in Uganda by three sec tions: Solanum, Afrosolanum and Benderianum.
This subspecies and S. nigrum as a whole constitute a Eurasian taxon. It has, however, spread to all other con tinents. The leaves are eaten in Uganda. Fruits are. how ever, reported to be poisonous (FAO 1988
The names S. nodiflorum Jacq. and S. nigrum L. have been widely and incorrectly used for this species. A detailed list of synonyms has been given by Edmonds (1972Edmonds ( , 1979a. Herb about 1 m high. Stem with simple hairs when young, glabrous when mature. Leaves 50-130 x 30-60 mm; mature lamina glabrous, margin repand or w ith 2-3 pairs of lobes, ± 5 mm long; petiole up to 50 mm long. Inflorescence lateral, umbellate cymes 2-10-flowered; peduncle up to 30 mm long. Corolla ± 3 mm long, up to 10 mm wide. Fruit globose, up to 9 x 10 mm. shiny black when ripe; fruit stalk 10-13 mm long, erect. Seeds 1 x 1 mm. 2n = 24 (Edmonds 1977 S. americanum is a morphologically variable species. Edmonds (1977) divided it into two varieties, i.e. var. americanum and var. patulum (L.) Edmonds. The former is pilose and the latter glabrescent.
S. americanum is an introduced weed. Its leaves are collected and eaten. It occurs in all the four geographical regions of Uganda. It is also widely distributed throughout Africa and around the world. It is of South American origin, probably recently introduced into Africa. It is believed to have donated at least 2 genomes to the hexaploid 5. nigrum L. (Edmonds 1979b).
The synonymy has been discussed by Henderson (1974) and Edmonds (1979a).
S. scabrum is a rare species in Uganda and is recorded only from the extreme southwestern part. Its leaves are eaten. In other parts of Africa, the West Indies and In donesia. it is cultivated for its leaves and young shoots (FAO 1988). The fruits are eaten in Europe, where it is known as "garden huckleberry'.
Its origin is unknown (Edmonds 1979b). Some authors, however, describe it as a native of Guinea. Heine (1960) has pointed out that S. scabrum, 'does not occur wild in Guinea, but is cultivated there as a pot-herb and for medi cal purposes; nor apparently is it a native of any part of Africa'. Morphologically it is distinct and genetically iso lated from other hexaploid solanums (Edmonds 1979b Edmonds 1972Edmonds , 1986. The typification of this species is discussed by Edmonds (1986).
S. sarrachoides is a relatively rare species in Uganda. It is not edible. It is originally from South America but now established across tropical Africa and naturalized in Europe. Edmonds (1979b) suggested that this species might be a diploid progenitor of the tetraploid S. villosum Mill, and therefore may have played a role in the origin of S. nigrum L. It is morphogenetically completely isolated from all other diploid solanums (Edmonds 1977).   Henderson (1977)].
S. villosum is native to Europe. It has become estab lished in Africa. In Uganda it occurs in three of the four geographical regions. Its leaves are eaten as spinach. S. grossedentatum seems to be native to Africa. Its ploidy level is unknown.
In Uganda it is fairly widely distributed, occurring in three of the geographical regions. It is a crop weed. The leaves are used as a vegetable and the fruits eaten by children. Scrambling herb, up to 1.5 m high, sparsely pubescent with simple hairs. Leaves ovate to lanceolate up to 1 (X) x 60 mm, petiole up to 20 mm long. Inflorescence branched once, racemose, 8 -20-flowered; inflorescence stalk ± 17 mm long; pedicels ± 8 mm long. Corolla 6-10 mm wide, lobes ± 3 mm long. Fruit stalk reflexed. ± 10 mm long. Fruit globose, 6 x 6 mm, purple to black when ripe. Ploidy level unknown. 5. florulentum is fairly common in geographical regions U2 and U4 of Uganda and it seems to be native to East Africa. Its leaves are eaten. It has been confused with S. nodiflorum Jacq. and S. nigrum L. sen.su lato. Erect or scrambling herb, up to 2.5 m high, glabrous or sparsely pubescent with simple hairs. Leaves ovate to lanceolate, entire or sinuate-dentate, 70-180 x 35-70 mm. Inflorescence simple, racemose, 7-12-flowered. Flowers 7-9 mm diam. Fruiting pedicels reflexed. Fruit greenish yellow or purple when ripe, 4-6 mm diam. Ploidy level unknown.
S. tarderemotum is closely related to S. florulentum but differentiated from it by its simple inflorescence. It also seems to be native to East Africa. In Uganda it is repre sented in all the geographical regions. Its leaves are eaten. This is a rather difficult section, complicated by species plasticity and the existence of numerous specific and in fraspecific names. Heine (1960) adopted a broad view of the species. He considered all material in this section from the f-WTA (Heine 1963) area to be S. terminate. This was split into three subspecies: inconstans, sanaganum and welwitschii. Jaeger (1985) recommended three species for this section: S. nakurense, S. tenninale and S. welwitschii. The subspecies of S. tenninale are not very clear cut.
Liana about 4 m tall. Leaves up to 110 x 65 mm. petiole up to 80 mm long. Inflorescence very manyflowered, often > 50 flowers: pedicels to ± 10 mm long: peduncles with terminal umbel, occasionally also with a few lateral umbels; lateral umbels subsessile or oc casionally with the lowest on short branches. Corolla ± 8 mm long, whitish purple or bluish purple. Fruit globose. ± 8 mm diam.. red when ripe.
Subsp. tenninale is quite widely distributed in Uganda and eastern Africa from Ethiopia to South Africa. For synonymy see Heine (1960Heine ( . 1963 and Jaeger (1985).
Subsp. sanaganum is quite close to subsp. tenninale in both vegetative and floral characters. The main dif ference between them is that the former has a paniculate, the latter an umbellate type of inflorescence. In Uganda it is less common than subsp. tenninale but it is widely distributed in upland forests of tropical Africa. For synonymy see Heine (1960).
Subsp. inconstans is rare, found in disturbed forest. In Uganda it has been collected from Mabira Forest. A list of synonyms is provided by Jaeger (1985).
S. welwitschii is found in the forests of western and central Uganda. It also occurs in secondary forests of western tropical Africa. For synonymy see Jaeger (1985).
S. nakurense is morphologically similar to S. terminate. It differs from the latter by being erect, and having smaller leaves which are more hairy than in S. terminate. Its in florescence is also generally simpler than in 5. tenninale.
S. nakurense is relatively rare in Uganda. It generally prefers the upland woodlands and open habitats. Climbing shrub. Leaves lanceolate, ± glabrous. In florescence terminal, a lax cymose panicle with > 50 flowers. Corolla violet, ± 20 mm diam.
The more or less glabrous 5. benderianum is closely related to the hairy S. runsoriense. It is very rare in Ugan da, only recorded from the Rwenzori Mts. It is common in Ethiopia, growing at an altitude of 2 500-3 6(X) m. S. macrothyrsum Dammer from the Comoro Islands is probably synonymous with S. benderianum (Jaeger 1985). Climbing shrub to 4 m high, with dense mealy pubes cence of much branched hairs. Leaves lanceolate upper surface with light cover of mostly simple hairs; lower sur face with a heavy cover of branched hairs. Inflorescence terminal, a lax cymose panicle with ± 50 or more flowers. Corolla light blue to purple. ± 20 mm diam.; filaments sometimes 3 mm long, anthers slightly longer, dehiscing by terminal pores and longitudinal slits running down wards from the pore.
S. runsoriense is a montane forest species occurring in Uganda on Rwenzori Mtn in the west and Mt Elgon in the east at or above the bamboo zone. It also occurs in Kenya at an altitude of 2 500-3 (XX) m. Jaeger (1985)  For synonymy see Heine (1963).
S. mauritianum is a widespread weed in Uganda and other parts of tropical Africa. The closely related species S. erianthum D. Don. and S. umbellatum Mill., established elsewhere in Africa (Bukenya & Hall 1988), have not yet been recorded for Uganda.
S. mauritianum. S. erianthum and S. umbellatum are native to the Americas. Their spread to Africa has been associated with the 16th century Spanish and Portuguese trade routes (Roe 1979). These species are colonizers of open ground: forest openings, stream borders and areas of human disturbance such as roadsides.
Reproduction in these plants is not only by seed, but apparently more commonly by adventitious roots from shallow roots to form large colonies. They are self-com patible, another characteristic of successful weeds. The colourful berries and frequently isolated plants suggest bird dispersal of seed (Roe 1979).
S. mauritianum has been widely known in the past as S. auriculatum Aiton but the publication of S. mauri tianum antedates this name by one year. Indumentum often stellate, prickles usually present. Anthers mostly slender, tapering to the tip and opening by small terminal pores or, if stout, narrowing abruptly to a small tip and also often opening by longitudinal slits near base, dehiscing introrsely or extrorsely by outward bending of the tips. Ovary glabrous. Fruit often large (7-) 10-8() ( -90-130 mm Jaeger (1985).
A list of synonyms is given by Whalen (1984).
Shrub about 1.5 m high. Stems densely covered with simple hairs ± 2 mm long, and slightly decurved prickles that are 5 mm long with base 2 mm broad. Leaves ±110 x 90 mm. lobed or doubly lobed to about !/2 width of leaf; lobes triangular; prickles on midrib straight, ± 17 mm long, base ± 1 mm broad, on primary lateral veins 3-8 mm long, hairs on upper surface mainly simple, on lower surface stellate mixed with simple hairs: petiole up to 70 mm long with simple hairs and straight prickles ± 13 mm long, base 1 mm broad. Inflorescence 3-4flowered; pedicel ± 7 mm long. Corolla violet or blue. ± 12 mm long. Fruit up to 50 mm wide, bearing a terminal nipple or mammilla. 5 mammillae or protuberances often present at base. Seeds brown. 2n = 22. 24 (Heiser 1971).
S. mammosum is an introduced ornamental which is rarely found in Uganda, being native to the Caribbean region of central America where it is found in disturbed habitats and where it is cultivated for its curious fruits which are used as a medicine and as a cockroach poison (Duke 1970
S. aculeatissimum generally grows in forest clearings. It is widely distributed throughout Africa. It also occurs in southeastern Brazil (Whalen 1984). It is likely to have been introduced to Africa several hundred years ago (Jaeger 1985).
S. aculeastrum is a native African species extending eastwards from Imatong Mts in Sudan to the Cape in South Africa and westwards from Cameroon highlands. It is rather variable. Jaeger (1985) divided it into 4 sub species (subsp. 1; subsp. 2; subsp. aculeastrum and subsp. thomsonii). It has many traditional uses (Bukenya 1993
An extensive list of synonyms is provided by Heine (1963), Whalen (1984) and Jaeger (1985). Shrub 1.0-3.0 m high; stem with stellate floccose hairs with 8-10 more or less equal arms; prickles ± 5 mm long with base ± 2 mm broad. Leaves ± 240 x 120 mm; margin sinuate or with 3 pairs of short lobes; middle lobe up to 20 mm long; both surfaces with stellate hairs; prickles on midrib ± 3 mm long with base ± 0.5 mm broad; petiole up to 70 mm long. Inflorescence up to 10-flowered; 1-5 flowers functionally female; pedicel ± 10 mm long. Corol la violet, ± 30 x 27 mm. Calyx, especially on the lower most flower, very prickly, prickles ± 2 mm long. Fruits globose, 30 x ± 27 mm. green with light green patches when young, yellow when ripe.
S. incanum sensu lato is extremely common in Uganda, occurring in all the geographical regions and different habitats. It is polymorphic, and its intraspecific variation requires a thorough study, especially experimental work. Jaeger (1985) treated S. incanum in Africa as a species aggregate and divided it into five groups. These include S. incanum group which occurs in the dry country scrub ot NE Africa and the middle East; S. lichtensteinii group which is found in wooded grasslands of southern Africa; S. panduriforme group which occurs in eastern southern Africa; S. campylacanthum group, a common shrub of disturbed ground in the grasslands of central. East and southern Africa and S. cerasiferum group which (X'curs in NE Africa extending to northern Nigeria. Lester & Hasan (1991) divided S. incanum sensu lato into four groups: Group A, including 5. lojeru Dunal. S. campylacanthum Dunal, S. delagoense Dunal and many other species recognised by Bitter (1923); Group B containing S. pan duriforme Dunal only and has the narrowest leaves of all the species; Group C being S. incanum L. sensu stricto (Hepper & Jaeger 1985); and Group D containing S. lich tensteinii Willd. and allied taxa.
Subshrub or shrub. 0.5-1.5 m high. Stem terete, glabrous or with stellate hairs; not prickly or with prickles ± 6 mm long. Leaves 150-460 x 80-300 mm. entire or with short lobes, ± 10 mm long to deeply doubly lobed with major lobes up to 80 mm long; young leaves bear on upper surface simple, or stellate hairs, either singly or in combination; lower surface with stalked stellate or more or less sessile stellate hairs; mature leaves glabrous or with simple hairs and stellate hairs; prickles present or absent on leaves, when present, principally on midrib and lateral veins; petiole very short to 70 mm long. Inflorescence lateral, racemose, 3 -1 2-flowered. Flowers: lowermost tlower or flowers hermaphrodite, larger than the rest and functionally female, distal flowers with short styles, func tionally male. Normally 1 -2(-5) hermaphrodite plus 1-4 functionally male flowers present. Corolla infundibuliform-rotate or campanulate, 20-35 mm long, white, light purplish or blue. Calyx not prickly or with prickles ± 10 mm long; fruiting calyx often accrescent. 15-50 mm long. Ovary glabrous or with short-stalked or sessile glandular hairs. Fruit depressed globose, 20-60 x 30-100 mm, green, ivory or purplish white with dark stripes; when ripe, yellow to brownish; stalk erect or decurved, 10-40 mm long. Seeds 3.0-4.5 x 2.0-3.6 mm. 2n = 24.
The S. macrocarpon complex is extremely variable. In this treatment the complex is taken as a combination of S. macrocarpon L. and S. dasyphyllum Schum. & Thonn. This is because Bukenya (1993) obtained fully fertile Fl and F2 hybrids (pollen stainability was 80-100%) be tween what was previously known as S. macrocarpon and S. dasyphyllum. All accessions of these taxa and of hybrids between them showed 12 bivalents at metaphase-1 of meiosis and regular disjunction indicating that they belong to the same biological species. Bukenya (1993) split the complex in Uganda into four major groups; two are cultivars. one is a semi-wild and the fourth is the wild group (formerly called S. dasyphyllum). Seme (1983), Bista (1983) and Jaeger (1985) were also of the opinion that the separation of S. macrocarpon and S. dasyphyllum is no longer justifiable. The S. macrocar pon complex is closely related to S. sessilistellatum Bitter which is endemic to Kenya, but distantly related to the S. incanum group (Whalen 1984).
The S. macrocarpon complex is native to Africa from where cultivars were introduced to other parts of the world. In Uganda, the complex, especially the wild group, is w idely distributed.
Small tree up to 10 m high. Stem bearing prickles, and stellate hairs on setae ± 1 mm long. Leaves ± 300 x 240 mm, with 2-3 pairs of prominent lobes up to 90 mm long, upper surface bearing simple hairs ± 1 mm long, lower surface with stellate hairs with 5-8 unequal arms on setae ± 0.5 mm long; prickles on midrib 10-20 mm long, base 4 mm broad; petiole ± 100 mm long; prickles on petiole up to 20 mm long with base 6 mm broad. Inflorescence > 20-flowered. Corolla blue to violet, turning white with age, up to 45 x 80 mm. Calyx ± 20 mm long; pedicel ± 25 mm long. Anthers of different length (2 ± 20 mm long, 2 medium. 1 short). Fruit globose, green when young with light green patches, yellow when ripe. 50 x 55 mm; fruit ing calyx about 20 mm long.
S. wrightii is an introduced decorative tree which is a native of Bolivia. It has been introduced to other tropical areas of the world. Perennial herb, often with several stems up to 0.7 m high. Stems with white stellate hairs, usually covered with dense straight yellow prickles. Leaves very' variable, up to 100 x 50 mm or more, ovate-lanceolate, prickly and hairy. Inflorescence racemose, with 6-10 flowers. Corolla blue-violet, 10-15 mm diam. Stamens unequal, one fila ment slightly longer than rest. Fruit yellow, globose, 10 mm diam.. dry. usually completely enclosed by heavily armed accrescent calyx. Seeds shiny black. Jaeger (1985) ux>k a broad view of the species to in clude S. dubium Fresen., S. tliruppi C.H. Wright. 5. depression Bitter and S. ellenbeckii Dammer. On the other hand Whalen (1984) used S. tliruppi for .V . dubium and commented that: 'S. dubium was published by Fresenius in 1834 but was pre-daled by S. dubium Dunal (1813) an unrelated species. A still earlier name is S. coagulans Forssk. (1775). but that epithet has been persistently misapplied and probably should be rejected'. This con troversy needs to be resolved.
S. coagulans is not common in Uganda. It has been collected from Ankole and Karamoja. These are pastoral areas and the species is noted to withstand overgrazing pressures due to its heavy armature and creeping nature. On the African continent, it tx'curs from Egypt to Tan zania. It has no clear relatives among the Old World solanums (Whalen 1984).
S. anguivi is a rather polymorphic species. It exhibits tremendous variation in features such as prickliness, pubescence and inflorescence. This variation is possibly partly due to domestication and partly to selection. There has been a shift from prickly, many-flowered and smallfruited types to prickless, less-flowered and laige-fruited types (Bukenya 1980). Bitter (1923) recognised more than 10 subspecies and several varieties for this species. Jaeger (1985) recognised five subspecies of S. anguivi. A revision of Bitter's in traspecific classification is necessary, following ex perimental work. Many of Bitter's infraspecific names are likely to be reduced to synonyms. No infraspecific com binations ot Bitter's subspecitic names have yet been pub lished for S. anguivi (Jaeger 1985).
In Uganda S. anguivi is a minor crop, grown for its fruits. It also grows as a weed, possibly dispersed by birds. S. anguivi is widely distributed on the African continent and its neighbouring islands, e.g. Madagascar.
The Gilo group is cultivated in Africa for its fruits; Aculeatum group is grown in several European gardens, not African; Shum group is a leafy vegetable in tropical Africa, and Kumba group is cultivated for its large fruits and leaves, especially around the Niger River.
The Gilo and Shum groups occur in Uganda. Lester & Niakan's system (1986) is followed.
The Gilo group is by far the most widely grown cultivar group of Solanum species throughout southern Ugan da. Its fruits are used in soup or stew preparation. I( is preferred to S. melongena because if has softer flesh than S. melongena. Within the Gilo group there is considerable variation, especially in the shape, size and colour of the fruit. This cultivar group is native to Africa and is believed to have arisen from the wild, weedy and semi-cultivated but poorly domesticated S. anguivi (Lester & Niakan 1986 Subshrub about 0.6 m high; stem glabrous. Leaves ovate, about 150 x 1 (X) mm. apex acute, base oblique, attenuate or truncate, margin repand; young leaves on both surfaces with small, sessile, stellate hairs with 5-8 more or less equal arms; mature leaves subglabrous; petiole 50-60 mm long. Inflorescence 3-10-flowered, sessile or flowers solitary, lateral; flowers hermaphrodite; pedicel ± 7 mm long with scattered stellate hairs. Corolla white. 5-7 mm long x ± 10 mm wide, glabrous; flower buds with dense stellate hairs. Calyx as long as the corolla tube. Style with stellate hairs. Fruit globose, 15-35 mm diam., green with dark green stripes when young, shiny red when ripe; fruiting calyx ± 7 mm long; stalk up to 12 mm long. Seeds 2.8 x 3.0 mm.
In Uganda the Shum group is a popular leaf vegetable in Buganda region, from where it has been introduced by migrants from Buganda to a few areas in western and eastern Uganda. It is native to Africa and is frequently cultivated in tropical Africa. It is less polymorphic than its relatives, the Gilo group and S. anguivi.
S. alhicaule has been collected from the dry region of Karamoja. It extends into NF Africa (Sudan, Somalia, Eritrea and Egypt) and west and NW Africa (Senegal. Chad, Mauritania). Elsewhere, it has been recorded for Arabia, Pakistan and India. It seems to be a species of arid lands. It has no close relatives in section Oliganthes.
S. cyaneo-purpureum is common in the shrub forests in the plains of southwestern Uganda. It also occurs in Rwanda, Burundi and eastern Zaire and often grows on termite mounds. It is related to S. taitense Vatke and S. hastifolium Hochst. For synonymy see Whalen (1984).
S. hastifolium is a deciduous bushland species of NE Africa, from northern Tanzania through Kenya and eastern Uganda to Sudan. Ethiopia and Somalia. It is rather polymorphic and often confused w ith S. taitense Vatke. It is also related to S. cyaneo-purpureum IX' Wild. Shrub up to 3 m tall, armed heavily with prickles, in dumentum pilose. Leaves ovate, up to 2(X) x 150 mm. margin lobed. base truncate and unequal and may be shortly attenuate, covered with stellate hairs. Inflorescence 8-to many-flowered rachis simple or branched, racemose. Corolla creamy white with a purple tinge on the veins, ± 10 mm diam. Fruit orange-red or red, ± 8 mm diam.
5. usambarense has often been confused with S. an guivi (S. indicum). Although the two are closely related, S. usambarense is easily distinguished from S. anguivi by inflorescence and infructescence characters.
S. usambarense occurs in the shrub layer of the forests on mountains of Rwenzori. Elgon and Kigezi. It also oc curs in the mountains of Kenya and Tanzania. S. giganteum is fairly common in Uganda. It is a dis junct montane species stretching southwards from Ethiopia to South Africa, and west to Cameroon. It has also been recorded in S India and Sri Lanka.
Shrubs up to 3 m high. Stem with broad-based prickles and scattered sessile stellate hairs with ± equal arms. Leaves elliptic, entire or repand, up to 150 x 70 mm; upper surface with sparse sessile stellate hairs about 6armed, middle arm much longer than rest, lower surface with sparse or heavy cushion of same type of hairs as on upper surface. Inflorescence cymose with flowers often subumbel late on branched peduncle, 10-20-flowered. Corolla violet. 7-10 x 14 mm. Fruit red when ripe, ± 7 mm diam.
S. kagehense group occurs in all the geographical regions of Uganda. It is common in the East African region as a whole, especially in thickets and areas of light shade between 6(X)-1 500 m. It is related to S. renschii Vatke. Some past plant collectors have confused it with S. giganteum. For synonymy see Whalen (1984) and Jaeger (1985).
Shrub or subshrub. Stem covered when young with small sessile stellate hairs w ith about 8 ± equal arms; stem and petiole bear broad-based prickles: veins with tiny prickles. Leaves 50-80 x 30-40 mm. ovate, entire; upper surface covered w ith same type of hairs as above; lower surface covered with a heavy cushion of sessile stellate hairs, larger than above and with more than 10 ± equal arms. Inflorescence corymbose, 20-50-flowered. Corolla pale violet, ± 10 x 13 mm. Fruit ± 8 mm diam., red/black when ripe.
S. renschii is endemic to eastern Africa, and is a vari able species. Jaeger (1985) suggested that S. kwebense N.E. Br" S. munitum Bitter, S. teitense Klotzsch and the material in his S. kagehense group could be incorporated in a broad concept of the species. Whalen (1984) lists S. tettense and 5. wittei A. Robyns as synonyms of S. renschii. S. wittei was included in Jaeger's S. kagehense group. If S. tettense and S. renschii are synonymous, then S. renschii should be sunk under S. tettense, having been published 21 years later than S. tettense. In Uganda S. renschii is restricted to the arid region of Karamoja. Herbs, rarely w(H)dy, often glandular-pubescent and aromatic, unarmed; hairs simple. Leaves mostly com pound or deeply lobed, but simple, entire leaves often present at certain stage. Inflorescence mostly paniculate; peduncles once or temately branched, often pendulous; pedicels mostly articulating near base or above it. Fruit 10-20 mm diam.
The subgenus is represented in Uganda by two sec tions: Petota and Jasminosolanum.

S.
tuberosum, is a mainly temperate crop introduced in East Africa about 1 (K) years ago by missionaries from Europe. The main area of commercial cultivation of potatoes in Uganda is Kigezi, a mountainous area with cool climate. Potato growing has spread to other highland areas in the country. Lowland areas also in recent years have started growing especially lowland cultivars. Potato blight seems to be a more serious limiting factor to cul tivation of potatoes than climate. Section Jaminosolanum Bitter ex Seithe in Botanische Jahrbiicher 81: 191 (1962);D'Arcy: 757 (1973). Type species: S. jasminoides Paxton.
Woody climber; stem terete, glabrous apart from oc casional tiny simple hairs. Leaves compound, imparipinnatc to deeply pinnatifid with about 7-9 leaflets or lobes; leaflets up to 50 x 30 mm. elliptic; lower leaflets with ± winged petiolule up to 5 mm long; upper leaflets (i.e. lobes) webbed together; lamina glabrous; margin ciliolate with sparse simple hairs; petiole up to 50 mm long. In florescence glabrous, mostly terminal or lateral, paniculate with up to 30 flowers or more; pedicel up to 7 mm long. Flowers hermaphrodite. Corolla blue to violet, up to 15 x 20 mm. Fruit spherical, ± 10 mm diam., red w hen ma ture; up to 40 from an inflorescence; fruit stalk 10-14 mm long. Seeds 2 x 2 mm.

S.
seaforthianum is an introduced decorative climber seemingly naturalized. It is native to central America and the West Indies, but has spread to many parts of tropical Africa, where it has been introduced for decorative pur poses.

CONCLUSIONS
Solanum americanum. S. tarderemotum, S. incanum. S. macrocarpon (wild group). S. anguivi and S. kagehense group are the most w idespread taxa in Uganda, occurring in all four geographical regions of the country. On the other hand. S. scabrum. S. terminale subsp. inconstans, S. benderianum. S. alhicaule, S. renschii and S. seaforthia num are the least widespread, occurring in only one region. The rest of the taxa are either fairly well dis tributed (occurring in three regions) or relatively rare (oc curring in two regions). This is associated with habitat preference and/or utilization.
There is tremendous morphological variation within the S. macrocarpon complex. Bukenya (1993) recognised four groups belonging to the S. macrocarpon complex in Uganda. These include S. macrocarpon (wild group-S. dasyphyllum)' , S. macrocarpon (semi-wild group). S. macrocarpon 'M ukono' cultivar and S. macrocarpon "Nahingo' cultivar. Sections Solanum and Oliganthes are also very variable. Experimental work on these taxa is still necessary to resolve their taxonomy.
At least 25 species in Uganda are useful or economi cally relevant. Pharmacological studies are needed to authenticate the medicinal potency of the various species used in traditional medicine. More attention should be paid to crops in terms of research to control pests and diseases, to increase yield and to produce well-adapted cultivars.