NOTES ON TROPICAL AFRICAN CONVOLVULACE^ 253 



and beech woods. The case of Denmark is too expHcit. The 

 beech, now the predominant species there, was unknown in the 

 Bronze Age, or, in other words, it reached Denmark and North 

 Lincolnshire at about the same period. In the Lower Peat bed 

 of that country the pine, which does not naturally grow there 

 now, took the same place as formerly with us. It was followed 

 in time by the oak and birch (which are now very rare though 

 areal in Denmark) before the beech arrived there. A good rule 

 for all students of our flora is — Deal with known facts, but be 

 very sparing of generalizations about the surmised past history 

 of species or formations. 



NOTES ON TEOPICAL AFEICAN CONVOLVULACE^. 

 By a. B. Eendle, D.Sc, F.E.S. 



The following notes were made during the determination of 

 collections recently received in the National Herbarium from 

 various parts of tropical Africa. The chief interest lies in the 

 plants brought by Mr. T. Kassner from the South-east Congo, 

 the affinity of which is largely Angolan, though partly East 

 African, corresponding with the intermediate position of the area. 



Ipomgea Eandii Eendle, hitherto known only from the type 

 specimen from Buluwayo, has been supplemented by a fine speci- 

 men sent by Dr. Eand (no. 1423) from Salisbury (The Commonage). 

 It has large handsome deep purple flowers. 



I. linosepala Hall, f., hitherto known only from Angola, where 

 it was found by Welwitsch and Gossweiler, has now been collected 

 by Kassner (no. 2300) in the Congo area — at Tonkoosji, Katanga, 

 near source of the Lubembe Eiver, in forest, at 5000 ft. altitude. 



Ipomoea alpina, sp. nov. Frutex ut apparet nana, strigosa, 

 ramis tenuibus hgnosis, superne dense foUatis. Folia lineari- 

 oblonga obtusa uninervia, breviter petiolata. Flores in axillis 

 foliorum superiorum solitarii, breviter pedicellati ; bracteis anguste 

 linearibus strigosis ; sepalis coriaceis, ovatis, longe-acuminatis, 

 sparse strigosis vel glabrescentibus ; corolla infundibuliforme. 



Hab. Mt. Senga, Congo, near Lake Tanganyika, on rocky over- 

 grown precipices at 5000 ft. ; in flower. May 29, T. Kassner, no. 2909. 



Apparently a low-growing plant ; shoots 7-8 cm. long, the 

 stem, leaves, and bracts bearing long stiffish white hairs springing 

 from a hardened base; stems about 1 mm. thick; leaves to 

 3-5 cm. long and -5 cm. broad, petioles 2-3 mm. long. Peduncle 

 3-5 mm. long, pair of bracts from about the middle of the peduncle 

 barely 1 cm. long, -4 mm. broad. Sepals about 8 mm. long. 

 Corolla, closed after flowering, 2-6 cm. long. 



Eecalls I. linoseioala Hall. f. in habit, indumentum, and the 

 narrow linear hairy bracts, but is distinguished by the narrower 

 leaves and the broader-based glabrescent sepals. 



I. velutipes Welw., an Angolan species (Golungo Alto), has 

 been collected by G. L. Bates in the South Cameroons, at Bitye, 

 near Eiver Ja. 



