100 A REVIEW OF THE BRITISH CHARACEiE . 



Key to the British Species. 



Coronula of 5 cells, persistent. With 1-2 circles of 

 stipulodes at the hase of the whorl. Chares. 

 Globule taking the place of the centre bract-cell. Stem 

 and branchlets with cortical cells (Chara). 

 Stem with three times as many rows of cortical cells 

 as branchlets in the whorls. (Triplostichce.) 

 Monoecious. Without spine-cells 1. C.fragilis. 



Dioecious. 



Stem destitute of spine-cells. 



Flexible. Branchlets of the male plant slightly 



incurved. With composite bulbils. . . 2. C. frag if era. 



Brittle. Branchlets of the male plant strongly 



connivent 3. C. connivens. 



Stem spinous 4. C. aspera. 



Stem with twice as many rows of cortical cells as 

 branchlets in the whorls (Diplosticha). 

 Dioecious. Bract-cells ovate. . . . . 5. C. tomentosa. 



Monoecious. Bract-cells slender. 



Primary cortical cells much larger than the 



secondary 6. C. polyacantha. 



Primary cortical cells smaller than the 

 secondary. 

 Stem with many spreading spines. Bracts 



whorled 7. C. hispida* 



Stem with few small appressed spines. Bracts 



on the inner side of the branchlets. . 8. C. vulgaris. 

 Stem with as many rows of cortical cells as branchlets 



in the whorls (Haplosticha) 9. C. canescens. 



Globule by the side of the nucule, within the whorl of 

 bracts. Stem and branchlets without cortical tubes 

 (Lychnothamnus). 10. L. alopecuroides 



Coronula of 10 cells, in 2 circles, deciduous. Stem without 

 cortical tubes or spines (Nitellce). 

 Globule lateral between the nucules. Rays of the 

 branchlets unequal (Tolypella). 

 Sterile branchlets simple. 

 Sterile branchlets obtuse. Ultimate segments of 



fertile branchlets of 2-5 cells 11. T. glomerata. 



Sterile branchlets acute. Ultimate segments of 



fertile branchlets rarely of more than 3 cells. . 12. T.prolifera. 



Sterile branchlets with lateral rays 13. T. intricata. 



Globules in the forking of the branchlets. Rays equal 

 (Nitella). 



Ultimate segments of the branchlets of 2-3 cells. 

 Sterile branchlets more than once divided. 



Very slender. Sterile branchlets 3 times divided. 

 Dark green. Whorls dense. Internodes 2-5 



times as long as the branchlets. . . 14. N. temdssima. 

 Light green. Whorls lax. Internodes scarcely 



exceeding the branchlets. , . .15. N. gracilis. 



Robust. Sterile branchlets twice divided. . . 10. N. mucvonata. 

 Sterile branchlets (appearing simple) only once 

 divided into 2-4 minute segments. Stem and 

 branchlets very stout. ... 17. jV. translucens. 



Ultimate segments of the branchlets of one cell." 



Monoecious. Fertile whorls usually lax. . . 18. N.flexilis. 

 Dioecious. Fertile whorls usually dense, , . 19. N. opaca. 



