8 POLY PODIACEAE. 
Family 5. POLYPODIACEAE R. Br. Prodr, Fl. Nov. Holl. 1: 145. 1810. 
FERN FAMILY. 
Ferns of various habit, the rootstocks horizontal, often elongated, or short 
and erect, the leaves simple, pinnate, pinnatifid or decompound, coiled in ver- 
nation. Sporanges borne in clusters (sori) on the lower side or margins of the 
leaves or their segments, stalked, provided with a vertical ring of cells, open- 
ing transversely. Sori with or without a membranaceous covering (indusium ). 
Prothallium green. 
About 7o genera and 3000 species of very wide geographic distribution. The family includes. 
by far the greater number of living ferns. 
Spore-bearing leaves closely rolled together, with necklace-like segments, 
: 1. Onoclea. 
Leaves all flat or their edges only slightly revolute. 
Sori dorsal or marginal, provided with special indusia. 
Sori roundish, indusia less than twice as long as broad. 
Indusium wholly inferior. 
Indusium roundish or stellate. 2. Woodsia. 
Indusium cup-shaped or somewhat 2-valved. 3. Dicksonia. 
Indusium partly inferior, fixed by a broad base and enclosing the sori like a hood. 
4. Cystoplerts. 
Indusium superior, fixed by its centre or sinus. 5. Dryopleris. 
Sori linear or oblong ; indusia more than twice as long as broad. 
Sori in chain-like rows parallel to the midribs or rachises. 7. Woodwardia. 
Sori all oblique to the midrib or rachises ; veins free. 
Sori confluent in pairs with an apparently double indusium pare 4 in the middle ; 
leaf simple. Scolopendrium. 
Sori single on the upper side of a veinlet or rarely crossing fe 
10. Asplentum. 
Sori partly parallel to the midrib, partly oblique; veins united. 9. Camplosorus. 
Sori with marginal indusia formed of the more or less altered edge of the leaf. 
Sporanges at the ends of veins, borne ona reflexed portion of the leaf. 
11. Adiantum. 
Sporanges borne on a continuous vein-like receptacle which connects the apices of the 
veins. 12. Pleris. 
Sporanges at or near the ends of unconnected veins. 
Leaves of two forms ; stipes pale. 13. Crvplogramma. 
Leaves uniform ; stipes usually dark colored. 
Sori mostly forming a continuous indusium around the segment. 
14. Pellaea. 
Sori minute ; indusium usually interrupted, if continuous the segments small and 
; bead-like. 15. Chetlanthes. 
Sori without indusia. 
Sori linear and marginal. 16. Notholaena. 
Sori roundish or not more than twice as long as broad. : 
Stipes articulated to the rootstocks ; leaves in our species a ae 
Polypodium., 
Stipes not articulated to the rootstocks ; leaves in our species BS, -pinnatifid or ternate. 
. Phegopteris. 
1. ONOCLEA L., Sp. Pl. 1062. 1753. 
Coarse ferns with the fertile leaves closely rolled up into necklace-like or berry-like 
segments, and entirely unlike the broad pinnatifid sterile ones. Sori round, borne on the 
back of the veins. Indusium very thin and membranous, hemispheric or hood-shaped, fixed 
at the inferior side of the sorus. Sporanges pedicelled, provided with a dorsal ring, burst- 
ing transversely. Fertile leaves unrolling at maturity, allowing the spores to escape, and 
remaining long after the sterile leaves have been killed by frost. [Name ancient, not 
originally applied to these plants. ] 
Three species, natives of cold and temperate regions. Only the following are known to occur 
in North America. 
Fertile leaf bipinnate ; veins anastomosing. 1. O. senstbilis, _ 
Fertile leaf simply pinnate ; veins free. 2. O. Struthiopteris. 
