Solanum (Solanaceae) in Ghana

Of the 22 species, subspecies and varieties in the genus Solanum L. (Solanaceae) that occur in Ghana, about 15 are indigenous. In Ghana serveral members of the genus are utilized as food crops while others are put to medicinal and ornamental use. Up-to-date and detailed descriptions for all the Solanum taxa occurring in Ghana and a key to the species are provided.


INTRODUCTION
The genus Solanum L. contains about 2 000 species of which about 15 are indigenous to Ghana.The rest have been introduced and are now cultivated crops, viz. 5. scabrum M ill., 5. melongena L. and 5. tuberosum L. Others are introduced ornamentals, including 5. mam mosum L., 5. capsicoides All. and 5. wrightii Benth., whereas 5. americanum Mill, and 5. arundo Mattei are weeds of recent introduction and a species introduced into Legon Botanical Garden, respectively.
The genus is of great economic importance, with seve ral species that are food crops, yielding edible leaves, fruits and tubers.Other species are medicinal plants, ornamentals or weeds of cultivation.The genus is widely distributed throughout the world.
Since the genus Solanum was described by Linnaeus in 1753, it has been reclassified innumerable times, and a multitude of species, subspecies and varieties has been named.The major revision of Solanum in Africa was done by Bitter (1913Bitter ( , 1917Bitter ( , 1921Bitter ( , 1923)), utilizing mainly collections from German expeditions.He erected a partial classification of Solanum.Despite some limita tions, especially the validity of some of his varieties which are based on minor variations and are of very local occurrence.Bitter's work is the most authoritative avail able today on African Solanum.D'Arcy (1972) provided a modem classification of the genus Solanum into subgenera, sections and series and his classification is widely followed today.
Although the above major works and others attempted to streamline the taxonomy of Solanum, the genus is a difficult one and is complicated by several factors.These factors include the difficulty of associating the names of Solanum used by earlier taxonomists with the plants of today due to early descriptions being brief, often vague and frequently lacking in characters now considered to be diagnostic.Again some of the early names, for exam ple many of the names of Linnaeus and those before him, were not typified, or if so, the type is not easy to discern (Hepper 1979).
Another problem is the occurrence of polyploid series within taxa (Edmonds 1977), for example tetraploids and hexaploids within the 5. nigrum complex.These may provide a barrier to hybridization between morphologi cally similar plants leading to cytoraces difficult to dif ferentiate using classical methods.
There is also considerable phenotypic plasticity within species and hybridization between closely related spe cies.Hybridization followed by inbreeding may result in formation of new populations different from either pa rent.This is particularly true for the cultivated species.A large number of 'microspecies' or 'semispecies' (Grant 1971) occur in section Solanum and it is problematical to decide how many of these deserve taxonomic recogni tion.
Today there is no single up-to-date work covering the classification of the entire genus in West Africa.Gbile (1979) made descriptions of Solanum species in Nigeria.His work was however based only on the herbarium specimens kept at the Forest Herbarium Ibadan (FHI).He therefore did not treat all the Solanum species occur ring in Nigeria.In Ghana itself not much work has been done on Solanum.Some data on Solanum are found in Floras, including the Flora o f tropical Africa (Wright 1906) and the Flora o f west tropical Africa (Heine 1963).In the Flora o f tropical Africa, species were viewed in a narrow sense and interspecific variation seems to have been ignored.Species delimitation was based on inadequate material and on few morphological characters.Wright (1975), Nsowah (1969) and Hossain (1973), studied a few species of Solanum in Ghana.Wright (1975), however, based his study on specimens collected from one district (Cape Coast), hence the complex range of variation of the species he studied, particularly S. nigrum s.l., could not be appreciated.Nsowah (1969) unfortunately did not identify with care the several strains of garden eggs he studied.
Such misidentifications occur because, unfortunately, the FWTA, edn 2 does not provide full descriptions for the West African Solanum spp.but only gives a key to the species.With a key alone one is likely to go wrong in identification of critical species and the key in this Flora does not, in some cases, bring out differences between closely related species.This flora, like the treatment of Solanum by Gbile (1979), does not give consideration to experimental work on cultivated species, e.g. S. gilo Raddi, S. aethiopicum L. and S. macrocarpon L., hence their variability was not appreciated.Critical species like 5. nigrum complex were treated only in the broad sense.
We have therefore attempted to provide detailed, upto-date descriptions of all the Solanum spp.occurring in Ghana.

MATERIALS AND METHODS
The gross morphological studies were based on about 200 specimens.A large number of these specimens were those already existing at the Legon herbarium, Ghana, whereas others were freshly collected by the authors from various regions of Ghana.
Information on all the specimens was recorded and the morphological characters of the species scored.For some o f the species, viz.S. nigrum s.I., S. americanum, S. scabrum, S. melongena, S. macrocarpon com plex, S. anguivi Lam ., S. aethiopicum L. and S. gilo, various accessions were collected from different localities in Ghana and were grown in an experimental plot at Legon.The morphological characteristics of the plants belong ing to the above species were observed throughout the various developmental stages and measurements of, for exam ple, flower and fruit characters were based on ma ture live plants.Specimens for the herbarium were ob tained from these plants.
After the study all the specimens were deposited at the Legon herbarium.Some of the specimens studied are cited under the species descriptions.The infrageneric classification of Ghana Solatium spp.(Table 1) is based on D 'Arcy (1972).
The genus is recognized by the 5-parted calyx and by long, often connivent anthers dehiscing by terminal pores and with short filaments.Other useful characters for recognition are the frequently rotate, 5-lobed corolla, the fruit being a berry with flattened seeds; often stellate pubescence and prickles; the often extra-axillary, usually cymose inflorescence.Leaves subentire or shallowly lobed, often membrana ceous, indumentum simple, hairs rarely branching.Prickles absent.Flowers mostly small, congested.Corolla mostly deeply lobed; filaments often pubescent.Anthers short, dehiscing introrsely by large, often oblique terminal pores and sometimes ultimately by longitudinal slits in the upper portion.Ovary glabrous.Fruit rather small, 7 -1 5 mm diam.
Herb, about 1 m high.Leaves elliptic, 6 0 -1 0 0 X 4 0 -7 0 mm; lamina glabrous when mature, margin entire or toothed, repand or with 2 -3 pairs of short lobes; petiole 1 0 -3 0 mm long.Inflorescence 6-8-flow ered; peduncle ± 10 mm long; pedicels ± 5 mm long.Corolla 3 -4 mm long.Fruits 5 -8 mm diam ., shiny black when ripe; fruit stalk ± 10 mm long.Seeds ± 1 x 2 mm.The name S. nigrum has been used in West Africa in a broad sense until the work of Edmonds (Gray 1968;Ed monds 1971Ed monds , 1972)).Edmonds identified some of the specimens we sent to her from the Ghana herbarium (Legon), and isolated three Ghanian taxa from the com plex.These are S. nigrum s. str., S. americanum M ill., and 5. scabrum Mill.The latter is easy to isolate from the other taxa on account of its fruit size (more than 10 mm diam.).The rest of the complex of species awaits a thorough analysis before tens of specimens in the Ghana herbarium can be placed in the correct taxa.S. nigrum complex is widely distributed in Ghana.la.subsp.nigrum.
Herb about 1 m high; stem with simple hairs when young, glabrous when mature.Leaves 50-80x30-50 mm; mature lamina glabrous, margin with two pairs of lobes, up to 10 mm long; petiole up to 20 mm long.Inflorescence lateral, umbellate cymes, 5-6-flow ered; peduncle ± 10 mm long; pedicel ± 7 mm long.Corolla ± 3 mm long; calyx ± 1 mm long.Fruit up to 9 x 1 0 mm, shiny black when ripe; fruit stalk 10-13 mm long; fruiting calyx 1 -2 mm long.Seeds l x l mm.2n= 24 (Edmonds 1977).Pollen diam. 1 7 ,7 -1 9 ,2 /xm. 5. americanum is an introduced weed, collected from the coast.The extent of its distribution will be fully known only after a thorough study of the S. nigrum com plex has been made.It is of S American origin, probably recently introduced into Africa.In Ghana S. scrabrum is known only in cultivation.It is grown for its edible leaves.The fruits, though eaten in Europe, where it is known as 'garden huckleberry', do not seem to be eaten in Ghana.It is of African origin, and has spread to America and other continents.
Subsp.inconstans is a rare taxon, found in disturbed forest.Both subspecies of S. terminale are restricted to tropical Africa.Shrub or small tree 4 -7 m high; young stem heavily covered with sessile stellate hairs.Leaves elliptic-ovate, entire, up to 230 x 180 mm; apex acute, base truncate, oblique or attenuate; both surfaces of leaves bear a heavy covering of stellate hairs with 5 -1 5 arms raised on se tae; petiole about 35 mm long.Inflorescence terminal, paniculate with numerous flowers.Flowers perfect; pe dicel ± 5 mm long, bearing more or less sessile stellate hairs with ± 15 arms.Corolla 7 -9 mm long, bearing sessile stellate hairs on the outer surface, and veins on inner suface.Calyx on both sides bearing sessile stellate hairs.Fruit spherical, pubescent, ± 8 mm diam ., green when young, yellow when ripe; fruit stalk ± 10 mm long.Seeds 1 x 1 mm.

S.
erianthum is a widespread tropical weed.S. erian thum and 5. torx'um form the most abundant shrub seed stock in Ghanian forest soils, with the greatest abun dance in the Moist Semideciduous, Dry Semideciduous and Southern Marginal vegetation types.When forests are cut the seeds germinate and these species form the most abundant secondary species.Fruits of S. erianthum are believed to be poisonous; leaves are used for healing 'Craw -Craw '.
The closely related species, S. mauritianum Scop, and S. umbellatum Miller are established elsewhere in Africa (R. N. Lester pers.comm.).These two species however have not yet been recorded for Ghana.Shrub about 1,5 m high; stem densely clothed with simple hairs ± 2 mm long, and slightly decurved prickles that are 5 mm long, base 2 mm broad.Leaves ± 110 x 90 mm, lobed or doubly-lobed, to about /: 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 both surfaces of leaves mainly simple, on lower surface some stellate hairs 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 -4 -flow ered; 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.S. mammosum is an introduced plant rarely seen, see mingly not naturalized.It is of South American origin, naturally growing in disturbed habitats.It has spread to other parts of the world as an ornamental plant.Its fruits are poisonous.Shrub ± 1,5 m high; stem densely pubescent, with simple hairs 0,1 -1 mm long, and decurved prickles up to 12 mm long with base 0,5 mm broad.Leaves ± 180 X 160 mm; lobed or doubly lobed to / width of leaf, with 3 -4 pairs of major triangular lobes; simple pilose hairs on both surfaces of leaves, rare stellate hairs on under side; prickles on midrib and petiole, slender, ± 15 mm long, base ± 2 mm broad, on primary lateral veins, slender, ± 7 mm long, base 0,8 mm broad.Inflores cence 3 -6 -flow ered; petiole, 4 -10 mm long.Corolla white, ± 12 mm long; peduncle 0 -0 ,5 mm long; pedicel ± 11 mm long.Fruit globose, ± 25 mm diam.Seeds 3 x 4 mm.Shrub ± 1,5 m high; stem bearing sparse simple hairs 4 -5 mm long, and prickles 2-10 mm long with base up to 2 mm broad.Leaves ± 150x135 mm, lobed or doubly-lobed to A -A width of leaf; lobes 2 -3 pairs, ovate; both surfaces with sparse uniform simple pilose hairs; margin ciliate; prickles on midrib ± 13 mm long, base 2 mm broad, on primary and secondary lateral veins 2 -7 mm long; petiole up to 50 mm long with simple hairs and prickles 14 mm long with base 2 mm broad.Inflorescence ± 4-flowered; pedicel ± 10 mm long.Corolla white or pale mauve, ± 12 mm long.Fruit globose, ± 45 mm diam.Seeds ± 1,5x2 mm, sur rounded by a wing ± 2 mm broad.
S. capsicoides has limited distribution in Ghana; appa rently introduced into botanical gardens as an ornamental plant; it does not seem to be naturalized.Its origin is South American (Brazil) and it has successfully spread to all continents as a weed with preferred habitat being drier, open lowlands.Shrub 1-2 m high; stem bearing stellate hairs; prickles strongly decurved, ± 8 mm long, base up to 5 mm broad.Leaves very small with 2 pairs of lobes ± 8 mm long, ± 35 mm wide; base attenuate; small stellate hairs with 6 -8 more or less equal arms on both surfaces; prickles on leaves straight, up to 12 mm long, base 3 mm broad; petiole ± 3 m long.Inflorescence racemose, op posite a leaf or slightly below; flowers up to 10 or more; pedicels ± 6 mm long, with stellate hairs.Corolla vio let, ± 13 mm long, with stellate hairs on the inner sur faces, on veins and on the outer surface.Fruits spheri cal, ± 13x12 mm, with more or less decurved stalks ± 14 mm long; young fruits variegated dark and pale green; ripe fruits brownish.Seeds 2x2 mm.

S. arundo was probably introduced into Legon Bota
nical Garden from northern Kenya; it is not naturalized.Its area of concentration is in the drier parts of east tropi cal Africa.It has also been recorded from the west coast of India.Shrub ± 1,5 m high; stem with stellate hairs of 8 -1 0 unequal arms.Leaves ± 1 5 0 x 100 mm, bearing on both surfaces short-stalked stellate hairs, margin with 2 -3 pairs of lobes up to 30 mm long; petiole about 40 mm long.Flowers usually solitary or inflorescence 2 -3flowered; pedicel ± 25 mm long.Corolla 20-22 mm long, purple, petal tips apiculate, incurved.Calyx about 10 mm long, normally not prickly but prickles 2 -3 mm long may occur.Fruit ovoid or globose, 6 0 -1 3 0 X 3 0 -1 0 0 mm, green, with white patches, white, or purple when young, orange-yellow to brownish when ripe; fruit stalk 2 0 -8 0 mm long, decurved.Seeds 3 x 4 mm.S. melongena is cultivated for its fruits which are eaten in stew and soup.It is a significant source of in come to horticultural farmers especially in the coastal parts of southern Ghana, the species is believed to have originated in Asia (Indo-Burma).It is cultivated on all continents for its edible fruits.Wr.: 238 (1906);Bitter: 200 (1923); Dalziel: 433 (1937); Heine: 332 (1963); Gbile: 118 (1979).Shrub 1 -1 , 5 m high; stem with stellate floccose hairs with 8 -1 0 more or less equal arms; prickles ± 4 mm long, base ± 1 mm broad.Leaves ± 160x120 mm, margin with 3 pairs of short lobes, middle lobe up to 20 mm long, both surfaces with stellate hairs; prickles on midrib ± 3 mm long, base ± 0,5 mm broad; petiole up to 70 mm long.Inflorescence up to 5-flowered; pedicel ± 10 mm long.Corolla violet, ± 18 mm long.Calyx, especially on the lowermost flower, very prickly, prickles ± 2 mm long.Fruits globose, ± 20 mm diam., green with light green patches when young, yellow when ripe.
S. incanum is a rare species in Ghana.It has not been collected since 1956.It is common in drier parts of tropi cal Africa and India.In Ghana it has been collected from one locality.

S. zanoni Gouan (1773) Gouan: 7 (1773).
Subshrub or shrub, 0 ,5 -1,5 m high; stem terete, gla brous or with stellate hairs more or less sessile or on robust setae up to 2 m long.Stem not prickly or with straight, robust prickles up to 6 mm long, base up to 3 mm broad.Leaves 1 5 0 -4 6 0 x 8 0 -3 0 0 mm, entire or with short lobes ± 10 mm long to deeply doubly-lobed with major lobes up to 70 mm long; young leaves bear on upper surface (especially on veins) simple, branched or stellate hairs on setae up to 2 mm long, either singly or in combination; lower surface with branched, stellate hairs on robust setae 0 , 5 -2 mm long and/or more or less sessile stellate hairs; leaf margin of young leaves with stellate hairs on robust setae up to 2 mm long or shortstalked glandular hairs; mature leaves glabrous or with simple hairs and stellate hairs on setae up to 2 mm long, upper surface with sessile stellate hairs; lower surface with stellate hairs on setae up to 2 mm long or sessile; leaf margin with stellate hairs on setae up to 2 mm long, sessile stellate hairs, branched or simple hairs; prickles present or absent on leaves, when present, principally on midrib and lateral veins, on mature leaves prickles on midrib and primary lateral veins straight, up to 13 mm long, base ± 3 mm broad, on secondary and tertiary lateral nerves up to 7 mm long, base 1 mm broad; leaf subsessile or with petiole up to 70 mm long.Inflores cence lateral, racemose, 3 -12-flowered, the lowermost flower or flowers hermaphrodite, bigger than the rest, distal flowers with short styles, functionally male, nor mally 1 -2 (-3) hermaphrodite plus 1 -3 functionally male flowers present.Corolla infundibuliform-rotate or cam panulate-rotate, 20-35 mm long, white, light purp lish or blue, the outer surface with simple, sessile stellate hairs or short-stalked or sessile glandular hairs, inner surfaces glabrous.Calyx not prickly or with prickles up to 10 mm long; outer surface with sessile stellate hairs, stellate hairs on setae up to 2 mm long, simple hairs or short-stalked glandular hairs; fruiting calyx often accres cent, 15-110 mm long.Ovary' glabrous or with shortstalked or sessile glandular hairs.Fruit depressed glo bose, 20-60 x 30-100 mm, green, ivory or purplish white with dark stripes; when ripe yellow to brownish; fruit stalk erect or decurved, 10-40 mm long.Seeds 3 -3,5 x 2 -3 mm.The S. macrocarpon complex is extremely variable.In Ghana it is cultivated mainly for its leaves, especially of plants with glabrous leaves.Leaves that are prickly have to be de-prickled before cooking.The fruits are also eaten.In other parts of Africa, e.g.E Africa, it is less cultivated.It is a native species of Africa from where it has been introduced to other parts of the world.It occurs in almost every region of Ghana.13.Solanum wrightii Benth. in Flora Hongkongensis: 243 (1861); Bitter: 180(1923); Heine: 248 (1960); Irvine: 733 (1961); Heine: 335 (1963); Gbile: 119 (1979).
Small tree up to 5 m high; stem bearing prickles, and stellate hairs on setae ± 1 mm long.Leaves ± 250 x 200 mm, with 2 -3 pairs of prominent lobes up to 80 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 1 0 -2 0 mm long, base 4 mm broad; petiole ± 60 mm long; prickles on petiole up to 20 mm long, base 4 mm broad.Inflo rescence ± 6-flowered; pedicel ± 20 mm long.Corolla blue to violet, up to 30 mm long.Fruit globose, green when young with light green patches, yellow when ripe.
S. wrightii is a decorative introduced tree; a native of Bolivia, it has been introduced to other tropical areas of the world.

S. anomalum auct. non Thonn.
Shrub 1,5-3 m high; stem bearing small, sessile stellate hairs with 4 -8 more or less equal arms; some times prickly.Leaves elliptic-ovate, 100-200 x 50-100 mm, sinuate to distinctly lobed, 2 -4 pairs of lobes, lobes 2 0 -3 0 mm long, apex acute to obtuse, base oblique, occasionally truncate or subcordate; leaves bear on both surfaces but nore so on the lower, more or less sessile stellate hairs with 6 -10 more or less equal arms; petiole 2 0 -6 0 mm long, with dense stellate hairs.Inflo rescence a raceme-like cyme, occasionally flowers soli tary, extra-axillary, many-flowered, 5 to more than 15, flowers mostly hermaphrodite, occasionally the distal flowers with short styles, functionally male; peduncle 0 -3 -6 mm; pedicel 1 0 -1 5 mm long, bearing stellate hairs.Corolla ± mm long, white, occasionally with light purple veins on the outer surface; with stellate hairs outside, more or less glabrous on inner surface.Fruit 7 -1 2 x 8 -1 2 mm, mostly globose, smooth, green when young, red when ripe; fruit stalk 8 -1 5 mm long, usually erect, occasionally horizontal or decurved.Seeds 1,5-2,1 mm long by 1 ,9 -2 ,9 mm wide.S. anguivi is widely distributed in Ghana, either wild or as a semicultivated plant for the fruits which are bitter and cooked in stew.The soup is taken before a meal as an appetiser.The species is widely distributed through out Africa as a semicultivated plant or as a weed in varying ecological situations.In Ghana it is found in all the regions.15.Solanum aethiopicum L., Amoenitates academicae: 307 (1759); Dalziel: 432 (1937); Heine: 332 (1963); Gbile: 115(1979).Subshrub, about 0,6 m high; stem glabrous.Leaves ovate, about 120 x 90 mm, apex acute, base oblique, attenuate or truncate; margin repand; young leaves bear on both surfaces small, sessile stellate hairs with 5 -8 more or less equal arms; mature leaves subglabrous; pe tiole 5 0 -60 mm long.Inflorescence 2 -3-flowered, ses sile or flowers solitary, lateral; flow ers hermaphrodite; pedicel ± 7 mm long with scattered stellate hairs.Co rolla white, 5 -6 mm long, glabrous; flower buds with dense stellate hairs; style also with stellate hairs.Calyx as long as the corolla tube.Fruit globose ± 18 mm diam ., green with dark green stripes when young, shine red when ripe; fruiting calyx ± 7 mm long; stalk up to 12 mm long.Seeds 2,8 x 3 mm.S. aethiopicum is occasionally cultivated by immi grants from Togo in southern Ghana for its leaves which are used as a vegetable.In other parts of tropical Africa, it is more frequently cultivated.Lester & Niakan (1986) treat it as Solanum aethiopicum Shumach group.In Ghana it was collected from one locality.Shrub 1 -2 m high; stem bearing tiny sessile stellate hairs of 4 -5 more or less equal arms.Leaves ellipticovate, 1 0 0 -2 4 0 x 7 0 -1 8 0 mm, margin sinuate-repand to distinctly lobed with 2 -4 pairs of lobes up to 50 mm long, apex acute, base oblique; both surfaces but es pecially the lower, with more or less sessile stellate hairs with 7 -9 unequal arms; petiole 1 5 -8 0 mm long; prickles may occasionally be present on early leaves.Flowers usually solitary or two next to each other, rarely 2 -5 or more arising from a common stalk, extra-axillary and hermaphrodite.Corolla ± 15 mm long, white, occa sionally light purple; petal tips apiculate, incurved; inner and outer surface of corolla with stellate hairs.Fruit ellipsoid, globose or oval, 13-70 x 1 3 -5 0 mm, smooth or with shallow longitudinal grooves, usually solitary, occasionally two or more together, green, white or purple when young, red when mature; fruit stalk 1 6 -4 0 mm long, mostly decurved.Seeds 3 x 4 mm.S. gilo is by far the most widely cultivated species of Solanum throughout the forest zone of Ghana.Its fruits are used in soup or stew preparation.It is preferred to S. melongena because it has firmer flesh than the latter.Where these two species are grown together sterile natu ral hybrids occur.
Shrub about 2 m high; stem bearing stellate hairs and prickles up to 8 mm long and 7 mm broad.Leaves up to 160 x 150 mm; margin subentire or distinctly lobed with 2 -3 pairs of lobes; lobes up to 50 mm long; base ob lique, attenuate or subcordate; young leaves with dense, stalked stellate hairs on both surfaces; mature leaves on upper surface with more or less sessile, stellate hairs, 4 -6 armed with one arm much longer than the rest; lower surface with stalked stellate hairs of 8 -9 more or less equal arms; petiole up to 70 mm long.Inflorescence a corymbose cyme; lateral, distal flowers with short styles, functionally male; peduncle ± 3 mm long; pedi cel ± 7 mm long, bearing glandular hairs.Corolla white, 10-12 mm long, outer surface bearing sessile stellate hairs, 6 -7 -a rm e d with one arm much longer than the rest, glabrous within.Calyx ± 4 mm long, lobes triangular, bearing glandular and sessile, 7 -8-armed stellate hairs on the outer surface, glabrous on the inner surface.Fruit globose, 10-15 mm diam ., yellow when ripe; fruit stalk up to 20 mm long. 5. tor\'um is a common weed throughout the tropics.Its fruits are collected in some parts of Ghana and eaten in soup and stew.S. torvum has a wide distribution in Ghana.Herb ± 0,5 m high; stem with shallow grooves when dry, and simple hairs.Stolons tuberiferous.Leaves com pound, interceptedly imparipinnate; major leaflets 5 -7 , alternating with ± 3 pairs of minor leaflets.Leaflets elliptic to oblong-elliptic, ± 50 x 25 mm; simple hairs on both surfaces; subsessile, margin entire; petiole up to 60 mm long.Inflorescence paniculate, with up to 10 flowers; pedicel 1 2 -1 5 mm long with simple hairs, ter minal on long peduncle ± 80 mm long.Flowers her maphrodite.Corolla white, 1 0 -1 2 mm long.Calyx ± 7 mm long, with simple hairs on the outer surface, gla brous within.Fruits globose, about 7 mm diam.S. tuberosum, the Irish potato, is a mainly temperate crop introduced to Ghana at about the time o f the Second World War.First introduced at Mampong (Ashanti Re gion), its cultivation was only slowly taken up by the inhabitants o f the area.Potato farming was therefore taken over by the Ministry of Agriculture, which grew it on big farms.The project was however abandoned.The crop spread to other areas.The present major potato growing areas are Pepease (Eastern Region) and Amedzofe (Volta Region), where it is grown early in the major rainy season by individual farmers and co-operatives.Potato is grown for its stem tubers, 90% o f which are consumed by foreigners. 5. tuberosum had its origin in the Andes (Bircher 1960).It was introduced to Europe, from where it spread to other parts of the world.The Ghana herbarium has not many collections of S. tuberosum.Bitter: 309 (1923); Irvine: 732 (1961); Heine: 332 (1963);D'Arcy: 758 (1973); Gbile: 117 (1979).

Vouchers: Ashanti
Woody climber; stem terete, glabrous.Leaves com pound, imparipinnate to deeply pinnatifid with about 7 -9 leaflets or lobes; leaflets up to 50 x 30 mm, ellip tic; lower leaflets with a more or less winged petiolule up to 5 mm long; upper leaflets (i.e.lobes) webbed to gether; lamina glabrous; margin ciliolate with sparse simple hairs; petiole up to 50 mm long.Inflorescence glabrous, mostly terminal or lateral, paniculate with about 20 flowers; pedicel up to 7 mm long.Flowers hermaphrodite.Corolla blue to violet, up to 10 mm long.Fruits spherical, ± 10 mm diam ., red when ma ture; up to 20 from an inflorescence; fruit stalk 1 0 -1 4 mm long.Seeds 2 x 2 mm. S. seaforthianum is an introduced decorative climber seemingly not yet naturalized.Its native home is central America and the West Indies.It has spread to many parts of tropical Africa where it has been introduced for deco rative purposes.The species has been recorded in Ghana.

DISCUSSION AND CONCLUSIONS
In Ghana, the most widespread Solanum species are S. tor\'um, S. aethiopicum Gilo group, S. nigrum s.I. and S. terminate subsp.welwitschii.On the other hand, the S. aethiopicum Shumach group, S. scabrum, S. inca num, S. capsicoides and S. aculeatissimum have res tricted occurrence.
Although some species are constant, for example S. torvum, S. erianthum and S. aethiopicum Gilo group, others are not.In cultivation, the S. macrocarpon com plex, for instance shows great variability.Bukenya & Hall (1987) identified, named and described six cultivars of the S. macrocarpon complex in Ghana.Bukenya 1980 (in unpublished M.Sc.thesis) studied experimentally the S. macrocarpon complex and proposed to sink 5. dasyphyllum under 5. macrocarpon.In our description of the S. macrocarpon complex, the former is therefore listed as a synonym of the latter.The classification and nomen clature of the infraspecific categories of the S. macrocar pon complex need to be revised.
A detailed study of the S. nigrum complex is required before the numerous specimens belonging to this com plex of species, available at the Legon herbarium, can be sorted out.
Experimental work on the difficult species of the ge nus has been recommended by Bitter (1923).Hawkes et al. (1979) and Edmonds (1979) as necessary to contrib ute to the improvement of the taxonomy of Solanum.
Cross breeding experiments have thrown some light on the taxonomy of the genus.Omidiji (1979) and Lester & Niakan (1986) for example, obtained fully fertile hybrids from crosses involving S. gilo and S. aethiopicum.The chemotaxonomic study by Pearce & Lester (1979) points to a very close relationship between S. melongena and S. anguivi.This has raised doubts as to the specific limits within the above sets of taxa.We agree with Heine (1963) that a modem revision of the entire genus is long overdue.

Bothalia 18,1 (1988)
S. aculeatissimum occurs wild in secondary forest, but is rare in Ghana.Ghana material has shorter hairs and less abundant prickles than specimens from the moun tains of Sierra Leone and Cameroun.The species is trop ical African, found in the tropical zone and in South Africa, but has close relationship to several South Amer ican species.All Ghana specimens come from the West ern Region. Vouchers:

Bothalia 18,1 (1988) long
, bearing small sessile stellate hairs on the outer surface, glabrous within.Fruit spherical, ± 6 mm diam ., green when young, red when ripe.Seeds 2 x 2 , 5 -3 mm. S. anomalum occurs wild in thickets and secondary forest in the drier parts of the forest zone.It seems to be restricted to West Africa. Vouchers: