HOW TO KNOW THE SEAWEEDS 



124a Main cell attached by several small rhizoidal cells at the base. 

 Fig. 164 Valonia ventricosa 



Fig. 164. Valonia ventricosa J. Agardh 



Habit of a small plant showing the basal 

 rhizoidal organs attached to a sand grain, 

 and two very young thalli attached to the 

 base, X 4. Common in some quiet water 

 habitats in southern Florida. This is a 

 famous plant on account of the size to 

 which a single cell may grow (to 3.5 cm.) 

 and the physiological experiments which 

 have been conducted upon it. 



Figure 164 



124b Main cell attached to crustose corallines by a penetrating peg. 

 Fig. 165 Halicystis ovalis 



Fig. 165. Halicystis ovalis (Lyngbye) Areschoug 



Habit of a plant showing the characteristic, 

 penetrating, basal peg, X 3.2. Epiphytic on 

 crustose corallines at lowest tide levels from 

 southern California northward. 



Figure 165 



125a Thallus with a midrib, median stipe, and (or) other veins. . . . 126 



125b Thallus without a midrib, median stripe or veins 143 



126a Thallus simple or branched only at the base 127 



125 



