208 University of California Publications in Botany [Vol. 8 



The determination of species of Cladophora presents unusual 

 difficulties. The synonymy, especially of older specific names, is very 

 much unsettled and intertangled. The identity between species of 

 different coasts and oceans is very uncertain, and the recognition of 

 species in their various ages and under varying conditions seemingly 

 most difficult. We have adapted our account very largely from Col- 

 lins (1909) and have accepted his determinations and limitations of 

 species, since we ourselves have very little opportunity for the study 

 of this genus and possess few facilities for the proper comparison of 

 our west coast plants with authentically determined specimens from 

 other coasts. It is desirable that collectors pay careful attention to 

 these plants, to their seasonal conditions, their fertile states, their 

 earlier stages of growth as well as adult, and attempt to make better 

 known the entire life-history of our various species and forms. 



Key to the Species 



1. Low, pulvinate or matted, creeping at the base 2 



I. Erect, tufted or loosely spreading 4 



2. Branching irregular, not at all dichotomous 1. C. amphibia (p. 209) 



2. Branching dichotomous or trichotomous, except above 3 



3. Main filaments 60-150^ in diameter 2. C. hemisphaerica (p. 209) 



3. Main filaments 120-250m in diameter 3. C. trichotoma (p. 210) 



4. Main filaments usually over 150^ in diameter 5 



4. Main filaments usually under 150m in diameter 9 



5. Lower segments 10 or more diameters long 4. C. graminea (p. 211) 



5. Lower segments less than 10 diameters long 6 



6. Ramuli curved 5. C. microcladioides (p. 212) 



6. Ramuli straight 7 



7. Ramuli only slightly less stout than branches 6. C. Hutchinsiae (p. 213) 



7. Ramuli very much less stout than branches 8 



8. Main filaments 112-200^ in diameter 7. C. ovoidea (p. 214) 



8. Main filaments 135-300m in diameter 8. C. MacDougalii (p. 214) 



9. Main filaments distinctly zig-zag or flexuous 10 



9. Main filaments straight or nearly so 13 



10. Ramuli clustered at the tips 9. C. laetevirens (p. 216) 



10. Ramuli not clustered at the tips 11 



II. Main filaments coarse, up to 150 (or 160) n 10. C. gracilis (p. 216) 



11. Main filaments slender, not over SOfx 12 



12. Segments long below (up to 6 diam.), shorter (as low as 2 diam.) above 



11. C. flexuosa (p. 217) 



12. Segments long throughout 12. C. Rudolphiana (p. 217) 



13. Ramuli curved 13. C. Bertolonii var. hamosa (p. 218) 



13. Ramuli straight 14 



14. Main filaments not over 30/x in diameter 14. C. albida (p. 218) 



14. Main filaments considerably over 30ai in diameter 15 



15. Ramuli acute 15. C. glaucescens (p. 219) 



15. Ramuli blunt ■■ 16 



16. Branching dichotomous below the tips 16. C. Stimpsonii (p. 219) 



16. Branching nowhere dichotomous 17. C. delicatula (p. 220) 



