SALVINIACE.E. 701 



or more ovoid sporocarps. These sporocarps or fruit usually have two teeth 

 near the base, and are 2-celled vertically, with many transverse partitions, and 

 split or burst into 2 valves at maturity. The sporocarps have a ring along 

 the edges of the valves, which at length swells up and bears the sausage- 

 shaped compartments from their places. The compartments contain macro- 

 sporangia and microsporaiigia intermixed. (Named for Aloysius Marsili, 

 an early Italian naturalist.) 



1. M. quadrifolia, L. Leaflets broadly obovate-cuneate, glabrous ; spo- 

 rocarps usually 2 or 3 on a short peduncle from near the base of the petioles, 

 pedicelled, glabrous or somewhat hairy, the basal teeth small, obtuse, or the 

 upper one acute. In water, the leaflets commonly floating on the surface ; 

 Bantam Lake, Litchfield, Conn., and now introduced in many places. (Eu.) 



2. M. vestita, Hook. & Grev. Leaflets broadly cuneate, usually hairy, 

 entire (2 -1" long and broad); petioles 1-4' long; peduncles free from the 

 petiole; sporocarps solitary, short-peduncled (about 2" long), very hairy when 

 young ; upper basal tooth of sporocarp longest, acute, straight or curved, lower 

 tooth acute, the sinus between them rounded. (M. mucronata, Braun.) In 

 swamps which become dry in summer; Iowa and southwestward. 



ORDER 13fi. 



Floating plants of small size, having a more or less elongated and 

 sometimes branching axis, bearing apparently distichous leaves ; sporo- 

 carps or conceptacles very soft and thin-walled, two or more on a com- 

 mon stalk, one -celled and having a central, often branched receptacle 

 which bears either macrosporangia containing solitary macrospores, or 

 microsporangia with numerous microspores. 



1. AZOLLA, Lam. (PL 21.) 



Small moss-like plants, the steins pinnately branched, covered with minute 

 2-lobed imbricated leaves, and emitting rootlets on the under side. Concepta- 

 cles in pairs beneath the stem ; the smaller ones acorn-shaped, containing at 

 the base a single macrospore with a few corpuscles of unknown character 

 above it ; the larger ones globose, and having a basal placenta which bears 

 many pedicellate microsporangia which contain masses of microspores. 



1. A. Caroliniana, Willd. Plants somewhat deltoid in outline (4-12" 

 broad), much branched ; leaves with ovate lobes, the lower lobe reddish, the 

 upper one green with a reddish border ; macrospores with three attendant cor- 

 puscles, its surface minutely granulate ; masses of microspores glochidiate. 

 Floating on quiet waters, from Lake Ontario westward and southward, ap- 

 pearing like a reddish hepatic moss. 



NATAXS, L., was said by Pursh to grow floating on the surface 

 of small lakes in Western New York, and has more recently been said to occur 

 in Missouri. It has oblong-oval floating leaves 4 - 6" long, closely pinnately- 

 veined, which bear conceptacles and branching plumose fibres on their under 

 surface. 



