NITELLA FLEXILIS. 



Var. c. nidifica. 



10/ 



Wallman Charac. p. 34 (1853) ; Nordst. & Wahlst. Exs. 9 ; Lloyd, 



Exs. 424. 



Fertile whorls with abbreviated brancUets, and form- 

 ing more or less dense heads, otherwise like the type. 

 Perth, E., Kerrj, S., Roscommon, Cavan. 



More extreme than var. subcapitata Braun (Braun, Rabenh., 

 & Stiz. Exs. 23), but connected with the type, and with var. 

 crassa, by intermediate forms. 



Var. d. Fryeri. 



Groves & Bullock- Webster in Joui-n. Bot. LVII, p. 101 (19].9). 

 ExsiccATA :— Nordstedt & Walilst. 10 ; Groves, 59. 



Markedly protandrous. AiitheriJinm much larger 

 than in the type, c. 800 ju, in diameter. Fruiting 

 ivlwrls forming more or less dense heads. Secondary 

 rays often mucronate. Oogonia 660-745 /^ long, 550- 

 610 jjL broad, 550 /a thick. Spiral cells showing 6-7 

 convolutions and distending considerably at the apex. 

 Oospore 500-520 )u, long, 426-450 /i, broad, 375 /.c thick, 

 dark reddish-brown to black, showing 5-6 stout pro- 

 minent ridges, often broadly and conspicuously flanged 

 towards the apex; outer membrane very thick and 

 semi-rigid. 



Cambridgeshire and adjacent Fenlands, where it has 

 been found by the late Alfred Fryer and G. R. B.-W. 

 in the following localities : — 



Cambridgeshire: Old Bedford River at Sutton Gault ; 

 Mepal Bridge at Mepal Drain, Welches Dam ; Manea ; 

 Sixteen Foot Drain at Stonea ; Stretham Ferry ; Drain 

 near Ely ; Wicken Lode. Norfolk, W. : Old Bedford 

 River at Welney; Little Ouse at Brandon Creek. 

 Huntingdonshire : Ramsey. 



The plant resembles N. opaca nither than normal N. flexilis 

 in stature and appearance, and in the density of the fruiting 

 whorls. The whole plant is often much incrusted. On speci- 

 mens gathered on 29th April, the antheridia were numerous, 

 and many had attained their full size, while few oogonia were 

 to be found, and these so small as to be hardly visible, so that 



