52 BRITISH CHAROPHYTA. 



9, 33 ; Jack, Lein. & Stiz. 206 ; Krypt. Exsicc. 1350 ; Lloyd, 418-19 p 

 Migula 127-8; Migula, Syd. & "Wahlst. 36, 56-8, 80-6, 145-7; 

 Nordstedt & WaMst. 106-7, 108a, 6, c, 109 a, b, 110-11, 112a, 6, 113-14; 

 Gr. & B.-W. 17, 18. 



Dioecious. Stem slender, with rather long internodes ;■ 

 root-nodes often producing solitary or clustered whitish 

 spherical bulbils. Cortex usually fairly regularly triplo- 

 stichous, the cells of the secondary series usually joining 

 obliquely, the primary series larger than the secondary. 

 Spine-ceUs normally, solitary, but occasionally geminate- 

 or even three together, spreading, long, slender, acute,, 

 often bulbous-based. Whorls of about 8 or 9 branchlets. 

 Stipulodes of both series well developed, usually long,, 

 slender and tapering, often bulbous-based, the upper 

 series sometimes equalling the lowest branchlet-segments 

 the lower rather shorter. Branchlets usually slender 

 and rather weak, sometimes stouter and firmer, straight 

 or somewhat incurved, of 6-8 segments, the ultimate 

 ecorticate and very acute. Bract-cells normally 5, all 

 weU developed, very variable in length, usually falling- 

 short of, but sometimes exceeding, the fruit, bracteoles 

 and bractlet usually longer than the bract-cells. Oogonia 

 and antheridia solitary, produced at the lowest 2-3 

 nodes. Oogonium 660-700 [j. long (excl. cor.), 450-525 \j. 

 broad; s^iraZ-ceZfe showing 13-15 convolutions; coronula 

 short, 75-100 [i high, c. 200 [i broad, spreading. Oospore 

 400-600 [L long, 250-375 (x broad, black, showing 12- 

 14 ridges terminating in basal claws ; outer membrane 

 thick laminated, brittle, opaque, duU brown, dehcately 

 granulated. Antheridium 500-600 [i in diameter. 



Habitat. — Characteristically a plant of lakes and large 

 ponds, but sometimes found in pools, canals and rivers. 



Distribution. — England: Cornwall, W., Devon, S., 

 Dorset, Wight, Hants, N., Surrey, Suffolk, E., Norfolk, 

 E. & W., Cambs, Hunts, Lines, S. & N.. Notts, Cheshire^ 

 Lanes, S. & W., Yorks, S.E., S.W., & N.W., Northumber- 

 land, Isle of Man. 



Wales : Glamorgan, Cardigan, Carnarvon, Anglesea. 



