362 Pub. Puget Sound Biol. Sta. Vol. 2, No. 53 



PLATE 61 



Figs. 1-5. Desmarestia foUacea. 



Fig. 1. Longitudinal section, showing young secondary veins without in- 

 vestment of assimilating cells, distinguished from conducting hyphae 

 by callose sieve plates. X 88. 



Tig. 2. The same as Fig. 1 but of older tissue, showing inner assimilating 

 tissue surrounding secondary veins. X 88. 



Fig. 3. Cross section of edge of frond, showing arrangement of tissues 

 and growing region at extreme edge. X 188. 



Fig. i. Base of stipe and central region of holdfast, showing central axis 

 extending into holdfast. X 88. 



Fig. 5. Longitudinal section of base of frond, showing central axis witii 

 pair of lateral branches surrounded by inner assimilation tissue and 

 conducting hyphae. X 88. 



Figs. 6, 7. Desmarestia acnleata (Linnaeus) Lamouroux. Longitudinal 

 and cross sections of main axis, showing arrangement of tissues and 

 size of cells as compared with cells of ligulate species. X 88. 



