Bothalia 25,1: 43-59(1995) Solanum (Solanaceae) in Uganda Z.R. BUKENYA* and J.F. CARASCO** Keywords: food crops, indigenous taxa, key. medicinal plants, ornamentals, Solanum. Solanaceae. Uganda, weeds ABSTRACT 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 of 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. UITTREKSEL Van die 41 spesies, subspesiesen kultivargroepe indie genus Solanum L. (Solanaceae) wat in Uganda voorkom. is sowat 30 inheems. Verskeie lede van die genus word as voedselgewasse benut. terwyl ander vir geneeskundige en omamentele gebruike aangewend word. Sommige lede is welbekend as onkruide. n Sleutel tot die spesies en beskrvw ings van al die Solanum-spes\cs wat in Uganda voorkom word voorsien. CONTENTS C. Subgenus Leptostemonum (Dunal) Bitter ........ 50 Section Acanthophora Dunal ............................... 51 Introduction............................................................... 44 15. S. mammosum L............................................. 51 Materials and m ethods............................................ 45 16. S. aculeatissimum Jacq................................... 51 Key to species........................................................... 45 Section Aeuleigerum Seithe .................................. 51 Solanum L.................................................................. 46 17. S. wendlandii Hook........................................ 51 A. Subgenus Solanum.............................................. 46 Section Melongena Dunal...................................... 51 Section Solanum.................................................... 46 18. S. melongena L............................................... 51 1. 5. nigrum L....................................................... 46 19. S. aculeastrutn Dunal................................... 52 la. S. nigrum suBsp. nigrum ............................. 47 20. 5. incanum L................................................... 52 2. S. americanum Mill......................................... 47 21.5. macrocarpon L........................................... 52 3. S. scabrum Mill................................................ 47 22. 5. wrightii Benth............................................. 53 4. S. sarrachoides Sendtn.................................... 48 Section Monodolichopus Bitter............................. 53 5. S. villosum Mill................................................ 48 23. S. eoagulans Forssk........................................ 53 6. S. grossedentatum A. Rich.............................. 48 Section Oliganthes (Dunal) Bitter ....................... 54 7. S. florulentum Bitter ...................................... 48 24. S. anguivi Lam............................................... 54 8. S. tarderemotum Bitter .................................. 48 25. 5. aethiopicum L............................................ 54 Section Afrosolanum Bitter .................................. 49 25a. 5. aethiopicum Gilo group......................... 54 9. S. terminate Forssk.......................................... 49 25B. 5. aethiopicum Shum group....................... 55 9a. S. terminate Forssk. subsp. terminate Heine 49 26. S. albicaule Kotschy ex Dunal ................... 55 9B. S. terminate suBsp. sanaganum (Bitter) Heine 49 27. S. cyaneo-purpureum De Wild....... ........... 55 9c. S. terminale suBsp. inconstans (C.H. Wright) 28. S. hastifolium Hochst. ex Dunal .................. 55 Heine........................................................... 49 29. 5. taitense Vatke............................................ 55 10. S. welwitschii C.H. Wright .......................... 49 30. 5. usambarense Bitter ex Dam m er............... 56 11. S. nakurense C.H. W right.......................... 49 Section Tona N ees................................................ 56 Section Benderianum Bitter.................................. 50 31. S. giganteum Jacq........................................... 56 12. S. benderianum Schimp. ex Dammer........ 50 32. 5. kageherLse group ..................................... 56 13. S. runsoriense C.H. W right........................ 50 33. S. renschii Vatke............................................ 56 B. Subgenus Brevantherum (Scithe) D 'A rcy........ 50 D. Subgenus Potatoe (G. Don) D 'A rcy................. 57 Section Brevantherum Seithe............................... 50 Section Petota Dumort............................................ 57 14. S. mauritianum Scop..................................... 50 34. S. tuberosum L................................................ 57 Section Jasminosolanum Bitter ex Seithe ........... 57 35. 5. seaforthianum Andrews........................... 57 * IX'partment of Botany. Makerere University. P.O. Box 7062. Kampala. Uganda. Conclusions............................................................... 57 ** Department of Biochemistry. Makerere University, P.O. Box 7062, Acknowledgements.................................................. 58 Kampala. Uganda. MS. received: 1993-06-29. References................................................................. 58 44 Bothalia 25,1 (1995) INTRODUCTION ‘more of a splitter than Dunal, and he described more than 60 new Solanum species from the Americas alone’ The genus Solarium L. Belongs to the family Sola- (Edmonds 1977). He recognised 20 sections for the genus, naceae, and contains about 2 000 species of which about and revised Solanum in Africa utilizing mainly collections 35 occur in Uganda. Several species are important food from German expeditions. He erected a partial classifica­ crops, yielding edible fruits and leaves whereas others are tion of Solanum. ornamentals or weeds (Heine 1963). The validity of some of Bitter’s varieties has been The genus also contains plants of medicinal value. For questioned Because they were based on minor variations example the fruits of S. anguivi Lam. contain alkaloids which are of very limited taxonomic value. However, his used in the treatment of a numBer of diseases including work is the most detailed treatment so far available on chronic respiratory diseases (Bector et al. 1971). Walters African Solanum. (1965) oBserved that Solarium alkaloids have antifungal effects. Thus it is possible that some of these alkaloids D’Arcy (1972) provided a modem classification of the could Be used as antibiotics. Beaman-Mbaya & Muham- genus Solanum into subgenera, sections and series and his med (1976) reported that alkaloids from fruits of S. in- classification is widely accepted today. It is also followed canum L. are used in treatment of cutaneous mycotic here. infections and other pathological conditions in Kenya. In Uganda, the soup from green fruits of S. anguivi Lam. is Although the above major works and others attempted popular especially among women, for it is believed to to streamline the taxonomy of Solanum, the genus is cure hypertension (Sengendo 1982). taxonomically difficult, due to various factors. These in­ clude the difficulty of associating the names of Solanum The genus is widely distributed throughout the world used by earlier taxonomists with plants of today due to with major species representation in America, Australia early descriptions being Brief, often vague and frequently and Africa. The genus was first studied by Dillenius lacking in characters now considered to Be diagnostic. (1732) and later By Linnaeus (1753). Since 1753 the genus Another problem is that some of the early names, for ex­ has been reclassified innumerable times and a multitude ample many of the names of Linnaeus and those before of varieties, suBspecies and species have been named, him, are difficult to typify (Hepper 1979). especially in the section Solanum. For example, Dunal (1813) in his monograph of the genus, descriBed 60 Another problem is the occurrence of polyploid series species belonging to section Solanum. Bitter (1912, 1913, within the section Solanum (Edmonds 1977), such as 1917, 1919, 1921, 1922, 1923) was the second worker to tetraploids and hexaploids occurring within the S. nigrum attempt to monograph the genus: he is criticized for being complex. These may provide a barrier to hybridization SUDAN KJtgum Moroto UGANDA Mubende ‘f/jfiRwenzori Mtn KAMPALA KENYA Lake Edward Lake Victoria FIGURE 1.—Geographical divisions. TANZANIA U l, U2, U3 and U4, of the Flam tVVAND o f tropical East Africa and the main towns of Uganda. Bothalia 25,1 (1995) 45 Between morphologically similar plants leading to Bukenya (1991) gave a comparative account of a few cytoraces which are difficult to differentiate using classical Solanum fruit and leaf vegetables. methods. To date the Solanaceae has not yet been treated for the There is also considerable phenotypic plasticity within Flora of tropical East Africa. Hence, to identify a species species and hybridization between closely related species. of Solanum in Uganda one has to use other regional floras, Hybridization followed By inbreeding may result in for­ particularly the Flora o f tropical West Africa, edn 2 (Heine mation of new populations different from either parent. 1963). However in this Flora, not all the species of This is particularly true for the cultivated species, as for Solanum occurring in Uganda are included and the example found in sections Melongena