Potamogeton,'] cliii. naiaIjace^ (bennett). 221 



with the ventral margin ; dorsal margin 3-keeled, and strongly repand- 

 denticulate, ventral nearly straight, with a projection in the centre 

 tapering to either end, variable as to the teeth-like projections on 

 various parts of the fruit, which are strongest on the Australian forms 

 —P. tenuicaulis, F. Muell. Fragm. i. 90, 244. P. parvifolia, Buchen." 

 in Abhandl. Naturw. Yer. Bremen, vii. 32. P. huillmsis, Welw ex 

 Schinz in Ber. Schweiz. Bot. Gesell. i. (1801) 61; Durand &, Scliinz 

 Conspect. Fl. Afr. v. 405 ; Rendle in Oat. Afr. PI. Welw. ii. 94. ' 



Upper Guinea. Niger Territory : Nupe ; in a deep lake near Jeba. Barter 

 1069»! 



Nile I.and. British East Africa : at the mouth of the Bahr el Arab, Schwein^ 

 furih, 1225 ! Niamniam ; in the River Rei (Rye), near Gumango Hill, Schiceinfurth 

 2909! -^ 



Xiower Guinea. Angola: Huilla ; in streams near Catumba, Welwitsch 

 248 ! River Cunene, Schinz, 1001 ! 



X^ozamb. Blst. British Central Africa : North-west Kalahari, Schinz ! (in 

 Serb, Buchenau). 



Also in South Africa, Madagascar, Australia, the Malay Archipelago and 

 Tropical Asia. 



5. P. crispum, Linn. Sp. PI. ed. i. 126. Stem compressed, 

 slender, branched. Leaves all similar, sessile, semiamplexicaul, strap- 

 shaped oblong or oblong, variously undulate, strongly serrate' at the 

 apex, less so on the margins ; stipules small, subobtuse, lower soon 

 decaying. Peduncles between the forks of the stem, rather stout, 

 tapering towards the apex; spike large, lax-flowered. Fruit large' 

 acuminate, compressed, obliquely-ovoid ; beak very long and curved! 

 — Durand & Schinz, Conspect. Fl. Afr. v. 493. 



Wile Xiand. Abyssinia: Nubia, Kotschy, 20! Babr el Tussuf, Steudner, 

 212 ! Kordofan, Kotschy, 366 ! CienkoiosJcy ! Senaar, ex Durand &■ Schinz. 



XMCozamb. Blst. British Central Africa : Nyasaland ; in Roangwa (Loangwa 

 River ?), Lake Nyasa, Kirk 1 



Widely distributed in all warm and temperate regions. 



6. P. lucens, Linn. Sp. PL ed. i. 126. Stem stout, branched. 

 Leaves all submerged; lower ones lanceolate or lanceolate-linear, 

 acuminate, with petioles gradually lengthening to 1-U, in., the lowest 

 sessile ; uppe? leaves lanceolate to ovate, acute, slightly firmer in texture 

 than the lower ; stipules long, beaked or winged. Peduncles 2-9 in. 

 long; stout, tapering upwards; spikes lJ-2 in. long, dense-flowered. 

 Fruits large, slightly acuminate, slightly convex on the ventral margin, 

 nearly semicircular on the dorsal, slightly keeled. 



Urile Xiand. Eritrea: Asmara, 7500 ft., Schweinfurth 4- Riva, 2110! 

 British East Africa ; in the Nile, Speke Sf Grant ! 



Also in Europe, Asia and America. 



YsLT.Jluitans, Coss. et Germ. Fl. Env. Paris, ed. i. 571. Leaves much longer 

 than in the normal form, up to 10 in. long, usually narrower, much darker in 

 colour, drying blackish-green, with longer petioles, ascending, not semi-patent &a in 

 the normal form. — P. longifoUmn, Gay in Poir. Eucycl. Suppl. iv. 535. P. macro- 

 phyllus, Wolfg. in Roem. & Schultes, Mant. iii. 358. 



