GENUS i. 



MARSILEA FAMILY. 



37 



i. Marsilea quadrifolia L European 

 Marsilea or Pepperwort. Fig. 85. 



Marsilea quadrifolia L. Sp. PI. 1099. 1753. 



Rootstock slender, buried in the muddy bot- 

 toms of shallow lakes or streams. Petioles usu- 

 ally slender, 2'-$' high, or when submerged 

 sometimes elongated to i or 2. Leaflets mostly 

 triangular-obovate, variable in outline, 3 "-8" 

 long, 2"-6" wide, glabrous or rarely with scat- 

 tered hairs when young, the margins entire ; 

 sporocarps 2 or rarely 3 on a branching peduncle 

 which is attached to the petiole at its base, 

 covered with short yellowish-brown hairs when 

 young, becoming glabrous and dark purple when 

 mature ; sori 8 or g in each valve. 



Bantam Lake, Litchfield Co., Conn. ; thence intro- 

 duced into other parts of the country, from Massa- 

 chusetts to Maryland. Native of Europe and Asia. 



2. Marsilea vestita Hook. & Grev. 



Hairy Pepperwort. 



Fig. 86. 



M. I'cstita Hook. & Grev. Ic. Fil. pi. 159. 1831. 



Mcrsilca iintcronata A. Br. Amer. Journ. Sci. 

 (II.) 3: 55- 1847- 



Rootstocks slender, creeping. Petioles slen- 

 der, 2 '-5' high ; leaflets similar to those of the 

 preceding species, entire or toothed; sporo- 

 carps 2" -4" long, 2 "-3" wide, with a short 

 raphe, a short and blunt lower tooth and an 

 acute and sometimes curved upper one, densely 

 covered with soft spreading narro\v hair-like 

 scales or (in the forms known as M. inucro- 

 nata) these short and appressed or almost 

 wanting; sori 6-n in each valve. 



In wet sand or in shallow ditches, Florida to 

 Kansas, Arizona and Mexico, California and 

 ^^^^^^ British Columbia. 



Family 7. SALVINIACEAE Reichenb. Consp. 30. 1828. 



SALVINIA FAMILY. 



Small floating plants with a more or less elongated and sometimes branching 

 axis bearing apparently 2-ranked leaves. Sporocarps soft, thin-walled, borne 2 or 

 more on a common stalk, i-celled, with a central often branched receptacle, which 

 bears megasporanges containing a single megaspore or microsporanges containing 

 numerous microspores. The megaspores germinate into prothallia which bear 

 archegones, the microspores into prothallia which bear antherids. 



The family consists of two genera. 



Leaves 6"-g" long, 2-ranked, on mostly simple stems. i. Sah'inia. 



Leaves minute, closely imbricated on pinnately branching stems. 2. Azolla. 



i. SALVINIA Adans. Fam. PI. 2: 15. 1763. 



Floating annual plants with slender stems bearing rather broad 2-ranked leaves, these 

 finely papillose on the upper surface. Sporocarps globose, depressed, g-14-sulcate, mem- 

 branous, arranged in clusters, i or 2 of each cluster containing 10 or more sessile mega- 

 sporanges, each containing a single megaspore, the others containing numerous smaller globose 

 pedicelled microsporanges with very numerous microspores. [Name in honor of Antonio 

 Maria Salvini, 1633-1729, Italian scientist.] 



About 13 species widely distributed. Only the following, the generic type, in the United States. 



