Family 7. 



MARSILEACEAE. 



2. Marsilea vestita Hook. & Grev. 

 Hairy Marsilea. (Fig. 74.) 



Marsilea vestita Hook. & Grev. Ic. Fil. />/. 759. 



1831. 

 Marsilea mucronata A. Br. Amer. Journ. Sci. 



(II.) 3: 55- 1847- 



Rootstock slender, creeping. Petioles 

 slender, 2'-$' high ; leaflets similar to those 

 of the preceding species, entire or toothed ; 

 sporocarps 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 

 narrow hair-like scales or (in the forms 

 known as M. mucronata) 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, north to British 

 Columbia. 



1828. 



SALVINIACEAE Reichenb. Consp. 30. 

 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 macrosporanges containing a single macrospore or microsporanges 

 containing numerous microspores. The macrospores germinate into prothallia 

 which bear archegones, the microspores into prothallia which bear antherids. 



The family consists of two genera. 



Leaves 6" -9" long, 2-ranked, on mostly simple stems. i. Salvinia. 



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



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



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

 Sporocarps globose, depressed, 9-i4-sulcate, membranous, arranged in clusters, I or 2 of 

 each cluster containing 10 or more sessile macrosporanges, each containing few macrospores, 

 the others containing numerous smaller globose pedicelled microsporanges with very 

 numerous microspores. Leaves rather dark green, finely papillose on the upper surface. 

 [Name in honor of Antonio Maria Salvini, 1633-1729, Italian scientist.] 



About 13 species of wide distribution. Only the following occurs in North America. 



i. Salvinia natans (L.) Hoffm. Salvinia. 

 ( p ig- 75-) 



Marsilea natans L. Sp. PI. 1099. 1753. 

 Salrinia natans Hoffm. Deutsch. Fl. 2: i. 1795. 



Leaves oblong, rather thick, obtuse or etnargin- 

 ate at the apex, rounded or cordate at the base, 

 entire, spreading, 6 / -i2 / long, pinnately veined, 

 bright green and papillose above, the lower surface 

 densely matted with brown pellucid hairs ; sporo- 

 carps 4-8 iu a cluster, the upper ones containing 

 about 10 macrosporanges, each containing a few 

 macrospores, the remainder containing numerous 

 microsporanges each with numerous microspores ; 

 macrospores marked with 3 obtuse lobes which 

 meet at the apex. 



Bois Brute Bottoms, Perry Co. Missouri and near 

 Minneapolis, Minn. Introduced into ponds on Staten 

 Island. N. Y. Reported by Pursh in 1814 from central 

 New \ nrk. but his exact station is unknown. Widely 

 distributed in Kurope and Asia. 



