FLORA OF THE DISTRICT OF COLUMBIA. 53 



2. Osmunda cinnamomea L. Cinnamon fern. 

 Wet woods, swamps, and low cut-over areas; abundant. May. Most of eastern 



N. Amer.; also in Asia. 

 The sprinfj 8ta,i,'e, often known as fiddleheads, is shown in plate 11. 



3. Osmunda claytoniana L. Interrupted fern. 

 Swamp edges, moist wooded slopes, or sandy alluvial soil; not very common, but 



found throughout. May. Eastern N. Amer.; also in Asia. 



3. SCHIZAEACEAE. Curly-grass Family. 



1. LYGODITJM Swartz. Climbing fern. 



1. Lygodium palmatum (Bernh.) Swartz. 



Wet thickets and borders of low woods; several restricted localities, Riverdale 

 Swamp, \dcinity of Suitland, Lanham, Arundel; probably of commoner occurrence. 

 Sept.-Oct. N. Eng. to Fla. and Tenn. 



4. POLYPODIACEAE. Fern Family. 



Leaves obviously of two kinds, the fertile ones with narrow, more or less altered 

 divisions. 

 Fertile blades with linear simple flat greenish pinnae, the large narrow sori arranged 



in a conspicuous double line 1. LORINSERIA. 



Fertile blades not at all leafiike, the spore-bearing parts greatly contracted, berry- 

 like or necklace-like, brownish, with the sori wholly concealed. 

 Sterile blades pinnately parted or divided, with netted veins; fertile parts a 



close berry-like cluster 2. ONOCLEA. 



Sterile blades pinnate, the pinnae very deeply pinnatifid, with free veins; fertile 



parts much simpler (once pinnate only), coarser, necklace- like. 



3. PTERETIS. 



Leaves uniform, the fertile ones not differing essentially in form from the sterile ones. 



Sporangia borne at the edge of the lobes or segments, either in definite clusters (sori) 



or as a continuous marginal line. 



Rootstocks widely creeping underground, slender, naked or hairy, devoid of 



scales. 



Blades erect, narrowly triangular-lanceolate, finely dissected; sporangia borne 



in minute cuplike indusia at the ends of the veins 4. DENNSTEDTIA. 



Blades nearly horizontal, broadly triangular, coarse; sporangia borne in a 



broad line within the margin, protected by a delicate continuous indusium. 



5. PTERIDIUM. 



Rootstocks erect or short-creeping, with a copious covering of imbricate scales. 



Blades delicate, the very numerous minute beadlike divisions glandular and 



freely clothed with pale rusty jointed hairs 6. CHEILANTHES. 



Blades coarser, the pinnules or segments comparatively few and large, flat, 



neither glandular nor hairy. 



Sporangia borne in a long continuous line, partly protected at first by the 



slightly revolute unchanged margin of the simple segment, eventually 



spreading, the margin becoming flat 7. PELLAEA. 



Sporangia borne in narrowly oblong individual sori, seA'eral to each cleft or 



lobed segment, seated on the inner side of the sharply reflexed modified 



tip of the lobe 8. ADIANTUM. 



Sporangia borne on the back of the segments in definite sori, distinctly apart from 



the margin. 



Blades simple, entire. Leaves 10-30 cm. long, the blades narrow, long-tapering 



from a cordate base, rooting at the tip, thus giving rise to new plants. 



9. CAMPTOSOEUS. 



