THE MARSILIAS. 20! 



The rootstock of this species is like that of Marsilia 

 quadrifolia in being wide-creeping. It grows beneath the 

 water and sends up its large leaves to the surface. These 

 are often two inches or more across, with deltoid seg- 

 ments having a rounded outer edge. Both sides bear 

 silky whitish hairs that seldom fall off at maturity. The 

 sporocarps are about a quarter of air inch long and are 

 very densely covered with long, tawny, hair-like scales. 

 The teeth are very small, the lower one often absent. 

 There are about twenty sori in each sporocarp. 



Marsilia macropoda has been thus far found only in 

 southwestern Texas and New Mexico. The woolly 

 nature of the leaves and fruit suggests that it may be an 

 extreme form of Marsilia vestita that has been modified 

 by its different habitat. While it is a lover of water it 

 may often be exposed to the air by the drouths of sum- 

 mer, and appears to be most fruitful when growing with 

 the minimum of moisture, as do most of the marsilias. 

 Baker writes the specific name macropus. 



Marsilia Tenuifolia. 



So far as known, the plant called Marsilia tenuifolia 

 has been collected but twice, both times in western 

 Texas. It has a close resemblance to Marsilia vestita and 

 by some is thought to be a form either of that species or 

 of Marsilia macropoda. It is described as being slenderer 

 than Marsilia vestita with an extensively creeping root- 

 stock. According to Underwood the leaves are villous 

 with appressed hairs and toothed on the margins ; accord- 

 ing to Baker they are nearly or quite smooth, with 

 entire margins. The sporocarps are said to be borne 

 singly upon short pedicels and to be tomentose. 



