^. 



H 

 t 



FRESHWATER HTDROCHARIDE^ OF AFRICA. 233 



in Madagascar, and an nndescribed species, B. radicans, mihi, 

 from Angola. The Stratiotese are well represented by a number 

 of species of Ottelia and Boottia. 



Only two of these genera are common to both the Old and New 

 World, viz. Vallisneria and Ottelia^ and of the latter but a sin^-Ie 

 species occurs in the N'ew World, viz. O. hrasiliensis in Brazil. 

 None of the genera are endemic to Africa, but all occur more or 

 less widely throughout Tropical Asia. Five of the African species 

 are natives also of Asia, viz. Hydrilla vertieillata, Casp., Blyxa 

 Roxbiirgliiiy Rich., LagarosipTion Boxhurghii, Benth., Ottelia alls- 

 moides^ Pers., Boottia cordata^ LindL ; and it is very interesting 

 to note that all these species are, as far as at present known 

 confined to Eastern Africa, the islands of Madagascar and Mau- 

 ritius. From this it may be conjectured that the Hydrocharideje 

 pushed their way into Africa from the East, perhaps, for the 

 most part, after the separation of the continents of Africa and 

 America was complete. At the same time it is possible that some 

 of these plants may have been introduced into the country in rice- 

 cultivation. 



Htdeille^. 



Lagabosiphon MUSCOinES, Harvey, Hook. Journ. Bot. iv. 



p. 230, t. 22. 



Cape of Good Hope, Harvey 1187 ; Zeyher 1732 ! ; Dreye 



2276 b c ! 



Var. MAJOE, n. var. 



Hyd 



latce. Eolia crassa atro-viridia opaca, | unciam longa, iV~¥ ^^^^> 

 costa obscura ; dentes breves obtusiores basi dilatati circiter 70 in 

 utraque margine ; margines pallida? folii angustissimse ; spatha 

 floris femineiferrae \ unciam longa, dentibus paucis obtusis brevi- 

 bus ; spatha mascula J unciam longa. 



South Africa, Undezine Kiver, Victoria, Cooper 17 ! Transvaal, 

 Hoggeveld, Bronkerspruit, no. 6559 ! and Trigardsfontein, 6678! 

 JDr. Behmann. Herb. Brit. Mus. 



This variety, though looking very distinct, seems to be only a 

 remarkably large and coarse form. It has the habit and texture 

 of Hydrilla. The leaves are so thick as to be almost opaque 

 under the microscope, instead of thin and transparent as in the 



Tva 



The 



are 



The 



spathes, although quite similar in form, are much larger. 



