THE MARSILIAS. 199 



There are often twenty-four or more sori in each sporo- 

 carp. A specimen is illustrated on page 188. 



Alarsilia uncinata is now known to occur from Louis- 

 iana to eastern Texas, and it is probable that its range 

 will be still farther extended. It appears to be plentiful 

 in the delta region of the Mississippi. When first 

 described it was thought to be a variety of Marsilia ves- 

 tita, but its longer rootstock, less hairy leaves, and spo- 

 rocarps will distinguish it from that species. In its 

 natural habitat Marsilia uncinata may be singled out 

 from the surrounding vegetation for some distance by 

 the peculiar fresh green colour of the leaves. During 

 the winter months either the plants disappear, or the 

 rootstocks remain in a resting condition without leaves, 

 though they reappear early in the new year. 



Marsilia Vest it a. 



The smallest of our marsilias, and the one with the 

 least predilection for a watery habitat, appears to be 

 Marsilia vcstita. While it often grows in shallow 

 water it is usually found on wet muddy banks, where it 

 may either grow in dense tufts or put forth short exten- 

 sions of its rootstock. 



The petioles are from one to five inches long, and the 

 leaves quite small, usually under an inch in diameter. 

 Both leaf and petiole are clothed with soft, short, white 

 hairs that may be either spreading or appressed. These 

 are so numerous on the younger parts of the plants as to 

 give them a hoary appearance. The outer edge of the 

 leaflets is rounded, entire or occasionally slightly toothed. 

 This is a variable plant, however, and all the characters 

 do not hold for single specimens. 



