A study of the genera Justicia L. and Siphonoglossa oerst. (Acanthaceae) in southern Africa

Abstract

A comprehensive revision of the genus Justicia L and, the closely related genera Siphonoglossa Oersted and Aulojusticia Lindau in southern Africa was undertaken as part of the Flora of Southern Africa project. Taxonomic characters re-examined include traditional morphological features and novel characters such as SEM studies of pollen~ seed and indumentum morphology, as well as chromatographic work on floral , pigments. Traditional morphological features examined included habit, the size and shape of leaves, the corolla, anthers and capsules. Inflorescence features were thoroughly re-examined. Pollen morphology was found to be diverse with three types of grain present in the genus. The number of colpi was either two or three and there were major differences in the appearance of the sexine. Pollen and inflorescence type were found to correlate. On the basis of this a natural infrageneric classification was proposed. The seeds showed a number of testa patterns: smooth, papillate, reticulate or with long scales. These types in many cases also correlated with the proposed infra-generic classification. The indumentum of leaves, stems and bracts was examined for each taxon, and in many cases proved valuable for identification of the taxon. The floral pigments were analysed using by 2D paper chromatography but, except in one species, did not prove useful in species or sectional delimitation. As a result of these studies, Justicia in southern Africa was divided into eight sections containing 22 species with six subspecies. One species and two subspecies were new and there is one new record for the region. These new taxa and a number of nomenclatural changes were published by Immelman (1986). The genus Aulojusticia was reassessed and is here regarded as a synonym of Siphonoglossa. Siphonoglossa, therefore, is considered' here to include three species and one subspecies in the southern African region. The species and subspecific taxa recognised in this revision are: Justicia 1. J. glabra Koenig ex Roxb. - N. Botswana, N. Transvaal and Zululand; also in tropical Africa. 2. J. campylostemon (Nees) T. Anders. - from N.E. Transvaal to E. Cape. 3. J. bolussi, C.B. Cl. restricted to the E. Cape and the Transkei. 4. J. betonica L. - from N. Namibia and N.E. Botswana, through the Transvaal to the E. Cape; also in tropical Africa and India. 5. J. montis-salinarum A. Meeuse - restricted to the Soutpansberg (N. Transvaal). 6. J. flava (Vahl) Vahl - from E. Botswana through the Transvaal and Natal to the Transkei, also widespread in Africa. 7. J. kirkiana T. Anders. - a common species in Africa, occurring in the region covered only from two localities in N. Botswana. 8. J. petiolaris (Nees) T. Anders. - (a) subsp. petiolaris from E. Transvaal to the Transkei (b) subsp. bowiei (C.B. Cl.) Immelman stat. nov. restricted to the E. Cape (c) subsp. incerta (C.B. Cl.) Immelman stat. nov. from the Transvaal and Zululand. 9. J. protracta (Nees) T. Anders. - (a) subsp. protracta from the Transvaal to the S. Cape (b) subsp. rhodesiana (S. Moore) Immelman stat. nov. from Namibia, W. Botswana and the N. and E. Transvaal. 10. J. parvibracteata Immelman sp. nov. - from the N. Cape, with one record from the N. Transvaal. 11. J. dinteri S. Moore Transvaal. N. Namibia, N.E. Botswana and W_o 12. J. odora (Forssk.) Vahl - N. Namibia, N. and E. Botswana, the Transvaal and Natal, also in tropical Africa. 13. J. capensis Thunb. N. Natal and also, disjunctly, the Transkei and E. and S. Cape. 14. J. cuneata Vahl - (a) subsp. cuneata which is restricted to the E. Cape (b) subsp. latifolia (Nees) Immelman from Namaqualand, W. Karoo and E. Cape (c) subsp. hoerleinlana (P.G. Mey.) Immelman stat. nov. from S. Namibia 15. J. Orchioides L. f. - (a) subsp. orchioides restricted to the E. Cape (b) subsp. glabrata Immelman subsp. nov. from the S. and E. Cape, E. Karoo, O.F.S., and S.W. Transvaal. 16. J.thymlfoila (Nees) C.B. C1. - restricted to the N. Cape. 17. J. guerkeana Schinz - mainly in S. Namibia. 18. J. platysepala (S. Moore) P.G. Mey. - mainly in N. Namibia. 19. J. minima A. Meeuse - endemic to the Waterberg (Transvaal). 20. J. a nagalloides (Nees) T. Anders. - Transvaal to Natal. 21. J. crassiradix Burkill & Clarke (new record for southern Africa) - one record from the E. Caprivi. 22. J. anselliana (Nees) T. Anders. - N. Namibia, N. and E. Botswana and the Transvaal. Siphonoglossa 1. S. leptantha (Nees) Immelman - (a) subsp. leptantha - from Natal to the E. Cape (b) subsp. late-ovata - (C.B.Cl.) Immelman comb. nov. ined. from the E. to the S. Cape. 2. S. nkandlaensis Immelman sp.nov. ined. - Central Natal. 3. S. linifolia (Lindau) C.B. Cl. (= Aulojusticia linifolia Lindau) - endemic to the Barberton area (Transvaal). A formal taxonomic revision including keys to genera, sections and species has been included.