THE TERRESTRIAL QUILLWORTS. 



T is singular that while the 

 quillworts of eastern Amer- 

 ica are mostly characterised 

 by megaspores marked with 

 spines and crests, those of 

 the West, especially in the 

 warmer parts, are marked 

 with fine dots and warts. 

 This apparent influence of 

 temperature on the mark- 

 ings of the spores is also 

 observed in the Southeast, 

 where the spines and crests 

 fade into tubercles. Along 

 with these peculiar patterns 

 of spore-markings in the West goes a tendency of the 

 plants to grow out of water, and in that region there are 

 several species that are by courtesy called terrestrial. 

 That they are terrestrial in the sense that a lily or a 

 dandelion is terrestrial is of course incorrect. Many of 

 these species are covered with water for a part of the 

 year at least, and the whole genus is so fully committed 

 to a watery habitat that they always grow in moist places. 

 When, for any reason, the places in which they grow 

 become dry, the plants go into a state of aestivation in 

 which the leaves disappear and the whole plant assumes 



