273 



tisli West India Islands, thougli not yet recorded. In estates' trenches ' 

 ponds and ornamental waters, this plant is a pest, from the freedom 

 with which it multiplies and the multitudinous number of the iadi- 

 viduals. The capsules are two to nine in number, or perhaps more, 

 about from one to three (sometimes none) of each cluster containining 

 macrosporan gia. 



Genus II: Azolla, Lam. Capsules situated in pairs in the axils of the 

 leaves beneath, of two kinds, membranous, indehiscent ; the larger, 

 subglobose, containing several or many microspores ; the smaller ovoid, 

 containing a solitary macrospore. Very small communal floating 

 weeds, branched, with miuute imbricating leaves in a double series, 

 sessile, with no veins, a central rib only in each, the inferior smaller 

 than the superior, and descending filiform simple villous roots. The 

 members of this genus like the last are communal and form a sheet 

 over water, often quite concealing the surface. They are exquisite 

 little plants in structure and colour, with minute imbricating leaves, 

 varying from green to dark purple in colour, branched in the form of 

 little prostrate trees. The species are about half-a-dozen, tropical and 

 subtropical, found in America, Asia, Africa and Australia. 



1. A. Caroliniana, Willd. — Entire plant in. each way, deltoid 

 or flabellate in outline, pinnate or bipinnate, obtuse, lower branches 

 longest, the lowest shortly branched again at the ends, leaves all united 

 at the axis, biserial on each side, those of the upper series larger, 

 more fleshy, brighter coloured, more erect and less appressed, subovate, 

 ^ - f li. 1., less broad ; those of the under side gray, appressed one on 

 the other ; sporangia in pairs, one of each or both of one kind together 

 in the axils of the leaves ; macrosporan gia several times larger than the 

 microsporangia, globose-oblong, the sack tender, membranous ; spores 

 uniform or variable in size spherical, pitted or reticulated, 6 - 24 to a 

 capsule, microsporangia ovoid, dark coloured, or striated, at each end. 

 The colour varies from light green to dark purple, but there seem to 

 be two varieties — green shading to pink, and pink shading to deep 

 purple, the former being larger in both plant and leaves. The spo- 

 rangia as a rule can only be detected by the use of a simple microscope, 

 but the macrosporangia may sometimes by the naked eye be seen to be 

 of a pale green colour, protruding between the leaves. Bak. Fern. AL 

 p. 138. My description is taken from Cuban specimen. The range is 

 so wide that there can be little doubt the species only waits to be re- 

 corded from Jamaica and some of the other islands. 



Tribe XTV.—Gleicheniece.^ 



Sporangia sessile, globose or subglobose, having a broad, complete i 

 transverse equatorial jointed band ; eventually bursting on one side 

 from top to bottom ; sori superficial on the back of the veins, puncti- 

 form, composed of few or several sporangia ; involucres none. 



The principal characters which distinguish this tribe are, — sporangia 

 sessile, globose, ring horizontal, equatorial, the rupture vertical. The 

 physiognomy, general habit, and manner of development of the fronds 

 are also singular. There is only one American genus. 



* This tribe was unfortunately omitted in its proper place. It ought to haT» 

 .iiome in at page 1 56 of this volume. 



