224 CLiii. NAiADACEiE (bennett). [Potaniogeton ^ 



bay. Kirk ! Kambone (Livingstonia) Lagoon, Laws, 3 ! Lukoraa (Likoma Island ?), 

 Sellingham ! 



A remarkable species, combining the habit of P. Rohhinsii, Oakes and P. pecti- 

 natum, Linn., but with the basal portion quite like a Cj/modocea, in texture and 

 rigidity. The lower stipules have membranous edges aud strong fibres, which 

 become frayed at the apex. 



The following species have been recorded from the African continent, but not 

 within the tropics, where, however, they are likely to occur : P. americanus, 

 Cham., and P. naians, Linn., occur in both North and South Africa ; P. Friesii, 

 Rupr., and P. alpinum, Balb., in South Africa; P. Zizii, Roth, P. densum, Linn., 

 P. trichoides, Cham., and P. perfoliatum, Linn., in North Africa. P. Zizii, Roth, 

 has also been found in Madagascar. 



4. BUPPIA, Linn. ; Benth. et Hook. f. Gen. PI. iii. 1014. 



Perianth none. Stamens 2 ; anthers 2-celled. Carpels 4, 1-ovuled ; 

 stigma sessile. Fruit of 4 long-stalked, ovoid, or oblique-ovoid achenes 

 on a common peduncle. Seeds uncinate ; radicle large. — Submerged, 

 slender, brackish-water plants. Leaves elongate, filiform ; sheaths 

 stipule-like. Flowers small, 2-6 (usually 2) together within the leaf- 

 sheath, on a short peduncle which mostly elongates, and becomes straight 

 or spirally twisted. 



Species 1 or more ? or many sub-species ? In all temperate and tropical regions. 



Leaf -sheaths inflated . . . . . . 1. JK. spiralis. 



Leaf-sheaths not inflated . . . . . . 2. It. rostellata. 



1. R. spiralis, Dum. Fl. Belg. Prod. 164. Leaf -sheaths inflated. 

 Peduncles spirally coiled. Drupes nearly straight. — R. maritimua^ var. 

 spiralis, Aschers. in Aschers. & Schweinf. 111. Fl. Egypte, 144 ; Durand 

 & Schinz, Conspect. Fl. Afr. v. 497. 



Upper Guinea. Senegal, Leprieur ! 

 Also in Egypt. 



R. acaulis. Gay MSS., may be a small form of the above rather than of R. ros- 

 tellata, judging by the fruits, &c. It was collected in Senegal by Leprieur. 



2. R. rostellata, Koch in Reichh. PL Crit. ii. 66, t. 174. Leaf- 

 sheaths not inflated. Peduncles short at the time of flowering, not 

 spirally coiled. Drupes obliquely ovoid. — R. maritima, Rendle in Cat. 

 Afr. PI. Welw. ii. 94, not of Linn. 



Upper Guinea. Lower Niger, Vogel ! 



[Lower Guinea. Angola : Pun|^o Andongo ; in a slowly flowing salt stream at 

 Salinas do Dungo, Welwitsch, 245. 



5. ZANNICHELLIA, Linn. ; Benth. et Hook. f. Gen. PI. iii. 1016. 



Male flowers: Anthers 2-4-celled; filaments slender. Female 

 flower with a membranous perianth. Carpels variable ; style long or 



