SALVINIACEAE 25 



the leaf-stalk, or are consolidated with it, containing both megaspores and 

 microspores. 



Sporocarps ovoid: leaves with 4-foliolate blades. 1. Marsilea. 



Sporocarps globose; leaves filiform. 2. Pilularia. 



1. MARSILEA L. 



Marsh or aquatic plants. Leaves commouly floating on the surface of shallow 

 water; blades slender-petioled, 4-foliolate. Peduncles shorter than the petioles, aris- 

 ing from their bases or more or less adnate to them. Sporocarps ovoid or bean- 

 shaped, formed of two vertical valves each with several transverse compartments (sori). 



Sporocarps 2-6 on each peduncle: leaves pubescent on both sides. 1. M. macropoda. 

 Sporocarps solitary or rarely 2 on each peduncle. 



Leaflets 4-16 mm. broad, obovate or nearly obcordate. 



Sporocarps 3-5 X4-7 mm. ; raphe short, with acute teeth. 2. M. vestita. 



Sporocarps 6 X8 mm.; raphe long, with long hooked teeth. 3. AI. uncinata. 



Leaflets 2-4 mm. wide, more or less falcate. 4. M. lenuifolia. 



1. Marsilea macropoda Engelm. Plant robust, 10-25 cm. tall. Leaflets 2-5 

 cm. long, 2 cm. wide, or less, usually undulate, whitish pubescent, especially so when 

 young: sporocarps 2-6 on erect branching peduncles, densely villous, 6-8 mm. long, 

 .5-6 mm. wide: raphe short, the lower tooth obtuse, the upper prominent or wanting: 

 sori 10 in each valve. 



In muddy places, Texas and New Mexico. 



2. Marsilea vestita Hook. & Grev. Eootstock slender. Petioles 5-13 cm. 

 high: leaflets entire or toothed: sporocarps 4-8 mm. long, 4-6 mm. 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 certain forms these 

 short and appressed or almost wanting: sori 6-11 in each valve. 



In wet or moist places, Kansas to British Columbia, Mexico, Texas and Florida. 



3. Marsilea uncinata A. Br. Plant 6-20 cm. tall. Leaflets nearly glabrous, 

 entire, 10-16 mm. wide, 8 mm. long: peduncles 15-30 cm. long, 2-4 times the length 

 of the sporocarps: raphe long, terminating in 2 approximate teeth, the upper longer 

 and mostly hooked: sori 13-14 in each valve. 



In swamps, Louisiana and Texas. 



4. Marsilea tenuifolia Engelm. Plant slender, 5-15 cm. high. Leaflets 2-4 

 mm. wide, more or less falcate, often slightly truncate and unequally toothed at the 

 apex, appressed-pubescent : sporocarj^s solitary, 5-8 mm. long, 4-5 mm. wide, the 

 teeth nearly equal, divergent : sori 9-12 in each valve. 



On borders of ponds, Pierdenales, Texas. 



2. PILULARIA L. 



Marsh plants with slender creeping rootstocks and few filiform leaves. Sporo- 

 carps globose, longitudinally 2-4-celled, dehiscing from the apex: cavities with 

 parietal cushions bearing microsporanges above and numerous megasporanges below. 

 Megaspores solitary. 



1. Pilularia Americana A. Br. Leaves filiform, about 2.5 cm. long. Sporo- 

 carps 2 mm. in diameter, attached by the side to a short descending peduncle, 3-4- 

 celled: microspores 13-17, not constricted at the middle. 



In shallow pools, Arkansas and California. 



Family 2. SALVINIACEAE Reichenb. Salvinia Family. 



Small floating plants, with a more or less elongated and sometimes branch- 

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

 borne 2 or more on a common stalk, 1-celled, with a central often branched re- 

 ceptacle, which bears megasporanges containing a single megaspore or micro- 

 sporanges containing numerous microspores. 



1. AZOLLA Lam. 



Minute moss-like reddish or green floating plants, with pinnately branched stems 

 covered with minute imbricated 2-lobed leaves, and emitting rootlets beneath. Sporo- 

 carps of two kinds borne in the axils of the leaves, the smaller ovoid or acorn- 



