HYDROPTERIDES. 
641 
side, surrounded by large rootlets, consisting of thin globular closed 
sporocarps or indusia, composed of a double membrane, bursting 
irregularly : these are of 2 kinds, one filled with many minute 
spherical globules, borne on branching pedicels from a central re¬ 
ceptacle ( antheridia ) ; the other containing larger bodies ( spo¬ 
rangia) short-stalked on a central receptacle, each including a single 
spore. (Named for Salvini , an Italian botanist.) 
1. S. llTitans, Willd. Leaves elliptical, obtuse, with clusters 
of bristly hairs above. —A small plant, “ floating like Lemna on the 
surface of stagnant waters in several of the small lakes in W. New 
York.” Pursh. — Not since found. 
3* AZOLLA, Lam. Azolla. 
Plant floating free, pinnately branched, clothed with minute imbri¬ 
cated leaves, appearing like a small Jungermannia : fructification 
sessile on the under side of the branches, of 2 sorts. Sporocarps or 
indusia ovoid, of a single diaphanous membrane : the smaller kind 
opening transversely all round, containing several roundish-angu¬ 
lar antheridia peltately borne on the sides of a central erect column : 
the large (fertile) kind bursting irregularly, filled with numerous 
spherical sporangia rising from the base on slender stalks, each 
containing a few globular hairy spores. (Name said to come 
from a£co, to dry , and oAXo>, to kill , being destroyed by dryness.) 
1. A. Carolinians*, Willd. Leaves ovate-oblong, obtuse, 
spreading, reddish underneath. — Pools and lakes, New York and 
westward, common in Ohio and southward. — Plant to V broad. 
Marsilea mucronAta, Braun, perhaps grows in Wisconsin. 
Class IV. ANOPHYTES. 
Cryptogamous acrogenous plants, growing upwards by an 
axis or stem, and usually furnished with distinct leaves 
(sometimes the stem and foliage confluent into a frond), 
composed of cellular tissue alone. 
Order 134. MUSCI. (Mosses.) 
Low , tufted plants , always with a stem and distinct ( sessile ) 
leaves , producing spore-cases which open by a terminal lid 
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