204 



J. O. HAOSTROM, CRITICAL RESEARCHES ON THE POTAMOGETONS. 



Stem-anatomy : The epidermis has a one-layered pseudo-hypodenna, but no 

 subepidermal strands are observed. Cortically there is only the ligular circle of 

 bundles. Endodermis of w-cells. The arrangement of the central bundles varying, 

 like that of P. lucens, from eight-bundled to oblong type. 



Unquestionably the species verv much approaches to P* 

 illinoensis. Especially the fruit-form is much the same in the two 

 species. The rostrum, however, seems to be a little longer in P. 

 capensis. The leaf-form is narrower and the submersed leaves 

 lack a lacunar system along the lateral nerves. Nor do they 

 present the recurved form and position as in P. illinoensis. 



From the hybrid P. Zizii it differs by the fruit, the narrower 

 peduncles, longer petioles, and obtuser leaf-apexes. 



It differs from all non-coriaceous-leaved species of the Lu- 

 centes by its upper leaves, and from P. ziziiformis, besides, by the 

 absence of subepidermal cauline strands, occurring in P. ziziiformis. 

 P. lucens, dentatus, malaianus and gramincus and others have 

 sharper-pointed submersed leaves, some of them even long-pointed. 

 Distribution. Africa. Cape. Zhyher (hb. Lund.); Zwart- 

 kopsrivier (Distr. Uitenhage) 1830 (hb. Stockholm.), one sheet 

 signed »019», another »8799» ; Prom. BonseSpei. Dbeoe (hb. Uppsal.); 

 In aquosis Mathibis Kom, in prov. Delagoa, 86, Bolus (hb. Uppsal.), 

 labelled: »Herb. Normale Austro-Africanum conflaverunt Macowa \ 

 et Bolus. Regio orientalis n:o 1393. Pol. lucens. L. »; Noted, 

 Umschlangwe River, 93, R. Schlechtkr n:o 3120 (hb. Stockholm 

 et Ziirich, labelled P. lucens L.). 



P. (hainissoi Ak. Bknn. 



B 



D 



Notes on Potamog., in Journ. of Bot., 1904, 74 — 75. 



The leaf-margin of this speoiea is furnished with a minute, 

 frail dentioulation like that of the Litcentes. The remaining 



properties also suggest that the species must be referred to this 

 group. The anatomical diagram of the stem does oot differ verv 

 much from that of the foregoing: Kpidermis, one-layered pseudo- 

 hyp., a full ligular circle of bundles, faintlv developed w-endoder- 

 mis (O-u-vnd.), and a central cylinder aceording to the eight- 

 bundled type. 

 The specimeo examined is gathered by Johnstom in »Riviére de Moha, Mauri- 

 lins, L889 (lil). Hann.). 



Fig. 101. /'. capensis 

 i \ Floating leaf 

 pocimi ni, | . /.', Bnb- 

 i ■ ■ > i -• 'i leal h "in < .ip", j . 

 C, Pistil, »i, Bide »ii 

 from behind the Di lagoa 

 plant), \' /', Ii -ni Bide- 

 vicw 1 1 >' iagoaplant), J. 



II. 



V. gramineus L. Sp. pl. 17. r >3, 127. /'. hcteropkyUus Sohbebbr, Spioilegium 

 lips., 1771, 21. - /'. graminifoUvs Bekkö, Transe., 1, 1 7 7 s , 123. P. liybridus 



