200 
The Ohio Naturalist. 
[Vol. XIV, No. 1, 
((b)). Synangia round, venation reticulate; leaves 
digitate. Kaulfussia. 
(b). Each loculus of the synangium opening by a termi¬ 
nal pore; leaves simple or simply pinnate. 
daw-eace.'E. Danaea. 
2. Plants leptosporangiate, sporangia developed from superficial cells. 
L F.PTO S PO R A X G IATZE. FILICALES. 
(1) . Sporangia without a true annulus, but with a group of thick 
walled cells which are sometimes arranged in a ring at the 
apex or side; sporangia nearly sessile; sporophores usually 
different from the foliage leaves or leaflets. 
a. Sporangia wfith an irrigular group of dorsal thick-walled 
cells, not arranged in a definite ring, globular; spores 
with abundant chlorophyll. 
OSMUXDACEiE. 
b. Sporangia with an apical ring of cells, ovoid. 
SCHIZ/EACE/E. 
(2) . Sporangia provided with a true, complete or incomplete 
annulus. 
a. Annulus usually complete; that is not interrupted by the 
stalk of the sporangium. 
(a). Sporangia mostly 2 to 8, not on a prolonged or pro¬ 
jecting receptacle; dehiscence vertical; indusium 
none, veins free. 
GLEICHRXIACE.E. 
(b). Sporangia on a convex, projecting or thread-like 
receptacle; dehescence vertical, diagonal, or trans¬ 
verse; indusium usually present. 
a. Sori round, on the end or the back, or in the 
axils of the veins. 
(a) . Sori with 6 to 10 sporangia. 
matoxiace/E. Matonia. 
(b) . Sori with numerous sporangia. 
CYATHEACE.-E. 
b. Sori always on the leaf margin at the end of a 
vein; leaf texture filmy. hymenophyllaceae. 
b. Annulus incomplete, interrupted by the stalk of the 
sporangium; dehiscence transverse; stalk usually long. 
a. Usually perennial terrestrial plants. 
POLYPODIACEJE. 
b. Annual hydrophytes; sporangia sessile, scat¬ 
tered, covered by the reflexed margin of the 
leaf, ceratopteridaceaj. Ceratopteris. 
II. Sporophyte heterosporous, producing two kinds of nonsexual spores; 
gametophytes much reduced, unisexual. 
1. Plants leptosporangiate, the sporangia in sporocarps, produced 
on the leaves; leaves without ligules. hydropterid.'E. 
a. Plants rooted, mostly perennial; sporocarp a modified 
leaflet with a thick, hard wall; terminal bud with a 3 
sided apical cell; megasporangia and microsporangia in 
the same sorus. MARSILEALES. marsileace.*. 
b. Plants floating, mostly annuals; sporocarp thin walled, 
representing a sorus; terminal bud with a two-sided 
apical cell; megasporangia and microsporangia in sepa¬ 
rate sporocarps. SALVINIALES. salvixiace.e. 
2. Plants eusporangiate; sporangia in the bases of the grass-like leaves 
not in sporocarps; leaves with ligules. 
Isoete.e. ISOETALES. isoftace/E. Isoetes. Quillwort. 
