202 
The Ohio Naturalist. 
[Vol. XIV, No. 1, 
POLYPODIACEjE. 
I. Sori naked or with marginal indusia. 
1. Sori naked or at least without a typical indusium and not covered 
by the reflexed margin of the leaf-blade. 
polypodiat/E. Acrostichum, Polypodium, Phegopteris, Vittaria. 
2. Sori marginal and usually covered by the reflexed margin of the 
leaf-blade. 
pteridata;. Notholasna, Adiantum, Petris, Pteridium, Pellaea, 
Cryptogramma, Cheilanthes. 
II. Sori with special indusia. 
1. Sori linear or oblong, more then twice as long as broad. 
aspleniat.e. Anchistea, Lorinseria, Asplenium, Athyrium, 
Phyllites, Comptosorus. 
2. Sori roundish, not more than twice as long as broad, usually nearly 
circular in outline, dryopteridat^e. Dryopteris, Polystichum, 
Oleandra, Nephrolepis, Davallia, Dennstaedtia, Filix, Woodsia, 
Matteuccia, Onoclea. 
Synopses of Marsileace.e and Sai.vixiace.e. 
MARSILEACE/E. 
a. Leaves with 4 leaflets; sporocarp bean-shaped, with 
several to many cavities. Marsilea. 
b. Leaves grass-like; sporocarp globose, with 2-4 cavities. 
Pilularia. 
SALVINIACEAE. 
a. With true water roots; sporocarps (sori) on the floating 
leaves. Azolla. 
b. Without roots but with root-like dissected leaves; 
sporocarps (sori) at the base of the submerged dis¬ 
sected leaves. Salvinia. 
Synopsis of the Calamophyta. 
I. Sporophyte homosporous; leaves united into a sheath with teeth; 
sporophylls shield-shaped, with sack-like sporangia on the lower or 
inner side; stem with a ring of vascular bundles and central pith which 
is usually hollow. Equisete.e, EQUISETALES, equisetace.e, 
Equisetum. Horsetail, Scouring-rush. Note.—The lowest forms are 
the large species with evergreen aerial stems of one type; the most 
specialized species have two types of annual aerial stems. 
II. Sporophyte heterosporous; leaves in whorls, free or united into a sheath; 
all fossil; some of the groups placed here are still imperfectly known 
and may be homosporous. 
1. Stems with a central triarch vascular bundle; leaves not fused into 
a sheath; sporangia stalked, on the upper side of the sporophyll. 
Paleozoic herbs or trees. 
Sphenophylle.e, SPHENOPHYLLALES. 
a. Leaves small or medium in size, usually more or less 
wedge-shaped. Sphenophyllace.e, Sphenophyllum. 
b. Leaves large, deeply pinnatifid. 
pseudoborniace/e. Pseudobornia. 
2. Stem with a ring of vascular bundles, increasing in diameter by a 
cambium zone, and with a central pith, usually’’ hollow; leaves 
whorled, free or at first united; Paleozoic plants often tree-like 
Calamarie.e, CALAMARIALES, calamariace.e, Calamodendron, 
Calamites, and other genera are recognized. 
