222 CLiii. NAiADACE^ (bennett). [Potamogeton. 



Ifpper Cvuiaea. Senegal : in Lake Guier, Soger-? ! Lepieur ! 

 X^ozaml). IDist. British Central Africa : Lukoma (Likoma Island?) in Lake 

 Nyasa, Bellingham f in the south-western bay of Lake Nyasa, Kirk ! 

 Also in South Africa, Europe, North America and Australia. 



7. P. coloratum, Hornem.Fl. Dan. t. 1449. Stem slender, branched. 

 Leaves all transparent and net- veined ; the upper sometimes nearly 

 sessile, very variable, elliptic to ^.Imost orbicular, never plicate at the 

 l)ase, and never (?) floating ; lovfer lanceolate ; stipules stout and 

 obtuse. Peduncles slender, nearly equal in diameter throughout ; 

 spikes long, cylindrical. Fruit small, greenish, rounded and keeled on 

 the dorsal margin when dry, but not when fresh, with no apparent 

 beak. — P. plantagiTieus, Du Oroz in Roem. & Schultes, Syst. Veg. iii. 

 504 ; Engl. Pfl, Ost-Afr. A. 80. P. helodes, Dum. Fl. Belg. Prod. 168. 



Stozamb. ISistt German East Africa : Usambara, ex Bngler. 

 Also in Europe, Australia and the West Indies. 



8. P, pusilluniy Zmn. Sp. PI. ed. i. 127. Stem slender, subterete, 

 branched. Leaves all similar, sessile, semiamplexicaul, narrowly linear, 

 acuminate, acute or subacute, 1-3-nerved, mostly without fascicles of 

 leaves in the axils; stipules small, acute, or subacute. Peduncles 

 slender, variable in length ; spike few-flowered, ^-^ in. long, not (or 

 very nearly) interrupted. Fruit small, semioval or obovoid, very 

 slightly compressed, bluntly 3-keeled on the dorsal face, slightly convex 

 on the ventral^ generally without teeth. — Hook. Niger Fl. 181, 528 ; 

 Durand & Schinz, Conspect. Fl. Afr. v. 496. 



Upper Cruinea. Cape Verd Islands ; St. Jacob's Island, Darwin ! Guinea, ex 

 Durand Sf Schinz. 



If lie Ijand. Abyssinia: Shireh ; near Arbatienseca, ^Mar;?t»-i)i7Zo»; and near 

 Adowa, Schimper (ex Richard). 



Xioiver Gruiuea. Angola, ex HooTcer. 



Mozaxnb. Sist. British Central Africa : Nyasaland ; in a pond in the 

 Residency gardens at Zomba, Whyte ! 



Widely distributed in all warm and temperate regions. 



9. P. Pretissii, Arth. Bennett. Stems branched, semiterete, striate. 

 Leaves all similar, linear for f of their length, then tapering, acute and 

 acuminate, 1|^-2J in. long, yg— ^jV ^^- hroad, generally curved from the 

 base to the apex towards the stem, stifier in texture than most of the 

 gramineuTri series, 3-nerved ; central nerve of 5-9 closely packed veins 

 with anastomosing cross veins ; stipules persistent, ^ the length of the 

 internodes, acute, with many fine veins. Peduncles 1-2 in. lonar, 

 slender, slightly tapering upwards ; spike ^-f in. long, dense-flowered. 

 Perianth-segments rhombic-orbicular. Fruit small, slightly compressed, 

 with a central beak, keels almost obsolete. 



upper Ciuiuea. Cameroons, Preuss, 451 ! Standi, 462 ! 



XTile Iiand. Eritrea : in the Gorge of Degerra, near Saganeita, 7200 ft., 

 Schweinfurth Sf Riva^ 896 ! Abyssinia : near Adowa, Schimper, 179 ! Amba Sea, 

 'Schimper, 570 ! Shireh Province, Quartin- Dillon Sf Fetit^ 571 ! 



