postelsia 



Marchantia and one or two other thal- 

 loid liverworts, a few mosses and a few 

 leafy liverworts are scattered sparingly 

 here and there in moist and well shaded 

 places. It is a rare thing to see a well 

 developed mat or carpet of moss larger 

 than a man's hand. During the wet 

 season a few mosses are rather abun- 

 dant on exposed rocks. Their season 

 for growth is very short, perhaps a 

 month or six weeks. Then they be- 

 come dried up and do not grow again 

 until the following year. The horse- 

 tails are represented by only two or 

 three species and these are not at all 

 abundant. One needs to know a local- 

 ity well in order to be able to find 

 enough of these plants for class work. 

 Woodsia, Cryptogramma, Asplenium and 

 Pteridium are met with in moist situa- 

 tions, but, as moist situations are not 

 common, these ferns are by no means 



