BOT.-VOL. II.] NOTT-CALIFORNIAN NITOPHYLLA. *] 



Remarks on Some Generic Characters, as Illus- 

 trated BY Californian Species. 



The Prostrate Frond. — The prostrate creeping frond 

 possessed by many species of Nitofhyllwn deserves special 

 consideration. Agardh makes some use of this character 

 in separating the genus into subsections, but the importance 

 of this structure to the plant and the extent to which it may 

 be developed have not, so far as it has been possible to 

 learn, been very fully demonstrated. 



Influence of Substratum.— The character of the sub- 

 stratum upon which the plant is located and the extent to 

 which it is exposed to the dashing, drawing, or swirhng 

 force of the waves affect both the amount of growth and 

 the shape of the prostrate frond. 



The various species of Nitophylhiin occur in a variety of 

 situations, from about mid-tide mark outward and down- 

 ward to deep water. They grow in some cases upon the 

 piles of wharves, where the prostrate frond must take advan- 

 tage of cracks in the wood or roughenings of the surface to 

 secure a foothold. Other species are found upon bare rock- 

 surfaces, exposed to the dash of breakers. The most com- 

 mon situation is that of those species which inhabit sheltered 

 rock crevices or pools surrounded by rocks which protect 

 them from the force of the waves. In such spots there will 

 usually be found upon the rocks a rich growth of Bryozoa 

 and Porifera, whose sponge-like substance affords an excel- 

 lent foothold for the plants and is conducive to a free devel- 

 opment of the prostrate 'frond. Other algae, notably the 

 Coralhnes, afford by reason of their jointed structure and 

 rough surface, excellent habitats. In general, the charac- 

 ters of the prostrate frond correspond to those of the erect 

 portion, but there are marked exceptions. N. latissimum, 

 for instance, possesses a membranous, broadly divided, 

 erect frond, while that of N. andersonianum is very much 

 branched. Two forms in the same genus could hardly 

 seem more widely different, yet the prostrate frond of the 

 two species is very much alike where growing under 



