180 Floristik, Geographie, Horticulfur und Systematik etc. 



oedevi pwnila [C. flava ptwtila iCo^?,. and Germ.) C. retrorsa robiiisotutii, 

 and C. bullata gveenii {C. gyeeiiü Boeckl.) Trelease. 



Gibbs, L. S. A contribution to the Botany of Southern Rho- 

 desia. (Journal of the Linnean Society, Vol. XXXVII. No. 262. 

 1906, p. 425—494. PI. 17—20). 



The collections, on which the present study is based, were 

 made in two localities in Southern Rhodesia, viz. in the Matopo 

 Hills and at the Victoria falls, Zambesi. There is a very marked 

 alternation oi" wet (Nov.-March) and dry periods and at the end of 

 the long dry period the country presents a ver}^ arid appearance. 

 The whole country is wooded consisting of small trees with spreading 

 crowns and intermingled under shrubs and belonging to the type 

 of Vegetation called a tree veld. Towards the end of October the 

 natives systematicalty burn the veld to expose the j^oung grass- 

 shoots to the cattle ; as a result of these fires and of the action of 

 the white ants there can be no accumulation of humus, and the 

 subsoil is covered b}- a very dry layer of loose sand , which probably 

 effectively prevents evaporation from the subsoil by interrupting 

 capillary action. All the prevalent factors thus tend to the even deve- 

 lopment of a certain vegetative type and everything promotes wide 

 distribution of species. The author newly records a number of 

 Angolan types and Cape plants. In the sj^stematic portion of the 

 paper (428—484) 23 new species are deseribed, the names being as 

 follows : Abictüoji niatopense; CorcJwrits niucilaginens; Crotalaria 

 (§ Oxarpae) flavicarinata Baker fil.; Elephantorrhiza mbesceus: Tenni- 

 nalia silozeiisis; Rotala longistyla; Brachylaena rhodesiaiia S. Moore; 

 Senecio tenellulus S. Moore; Nitxia viscosa; Hygrophila (§ Enhygro- 

 pJiila) cataractae S. Moore; Heniigraphis priineUoides S. Moore; Di- 

 spernia visadissimimi S. Moore ; Walafrida chougiveeiisis Rolfe ; Vitex 

 isotjensis; Loranthiis (§ Sapirvanthiis) sanibesicus ; Croton (§ Eucroton) 

 barotsensis; HesperautJia niatopensis; Eriocaidon aniplübium Rendle; 

 E. rnntopense Rendle; Fuiveun siibdigitata C. B. Clarke; F. Oedipus 

 C. B. Clarke ; Eviauthiis teretifoliiis Stapf. 



In the subsequent portion of the paper the author deals in brief 

 with the ecolog}^ of the flora under consideration. In the country 

 surrounding the Victoria Falls three distinct formations may be 

 distinguished, viz. the veld, the Eitgeiüa gui)ieeiisis formation, and 

 the Eiigenia cordata formation. These are due to edaphic rather 

 than to geological conditions. The veld Supports an open, deciduous 

 fürest growth of rather small dimensions (tree steppe). The Eugenia 

 guineensis formation includes the immediate banks of the Zambesi 

 above the Falls and the many green island in the river; the Engen /a 

 is accompanied by a fringe of Phragiuites occasionall}^ interrupted 

 by clumps of Papyrus and Erianthiis teretifoliiis, numerous other 

 plants being intermingled. The Eugenia cordata formation is deve- 

 loped in the so-called Rain Forest and is partly of a boggy cha- 

 racter. — The Matopo Hills consist of bosses of eruptive granite 

 forming kopjes (100— 150 feet high) massed against one another and 

 wooded to the top; they may or may not be separated by tv^pical 

 tree-veld (with Tertninalia sericea), whose level varies from 4—5000 ft. 

 The North-Eastern region is much better watered than the rest, so 

 that there is a finer growth of trees and large bog-areas (vleis) occur 

 in the wider Valleys (with Lobelia decipiens, Xyris capetisis, etc). 



