FILICES. (FERNS.) 59J 



mediate between the sterile and fertile condition, (bearing a few fruit-dots on con- 

 tracted but still herbaceous and open pinna;,) were gathered at Brattleborough, 

 Vermont, by Mr. D. C. Eaton. (Eu.) 



3. ALLOSOBUS, Bernhardi. Rock Brake. (Tab. 9.) 



Fruit-dots a small collection of sporangia borne on the ends of (or extending 

 down on) the forked, or rarely simple, free veins, which terminate just within 

 the margin of the frond, soon becoming confluent laterally, so as to imitate the 

 marginal continuous line of fructification of Pteris, covered when young by a 

 continuous (rarely interrupted) rather broad scarious-membranaceous indusium 

 consisting of the reflexed and altered margin of the fruit-bearing pinnule or 

 division. Fronds once to thrice pinnate; the fertile ones or fertile divisions nar- 

 rower than the sterile. (Name from ciWos, various, and acopos, sorus, a hi up, 

 used for fruit-dot.) 



1. A. gracilis, Presl. Smooth, low (3' -6' high, and delicate) ; fronds 

 membranaceous, of few pinna;, which are pinnately parted into 3-5 divisions, 

 those of the fertile frond oblong or linear-oblong, of the sterile ovate or obovate, 

 crenate or incised ; veins of the fertile fronds mostly only once forked. (Pteris 

 gracilis, Michx.) — Shaded calcareous rocks, Vermont to Wisconsin, and north- 

 ward ; rare. July. 



2. A. »tl'Oi»m'l>BireMS. Smooth, except some bristly-chaffy hairs on 

 the midribs and especially on the dark-purple and jiolished stalk and rhachis, 6'- 

 15' high ; frond coriaceous, pale, once or below twice pinnate; the divisions 

 broadly linear or oblong, or the sterile sometimes oval, chiefly entire, somewhat 

 heart-shaped or else truncate at the stalked base; veins about twice forked. 

 (Pteris atropurpurea, L. Platyloma atropurpurea, ./. Smith.) — Calcareous dry 

 rocks, in shade, Vermont to Wisconsin, and southward : not common. 



A. (Cryftogramma, R. Br.) acrostichoides, remarkable for its sporan- 

 gia extending far down on the oblique veins, so as to form linear lines of fruit, 

 may occur within our northwestern borders, having been found as near as Isle 

 Royale, Lake Superior. 



4. PTERIS, L. Brake. Bracken. (Tab. 10.) 



Fruit-dots a continuous slender line of fructification, occupying the entire 

 margins of the fertile frond, and covered by its reflexed narrow edge which 

 forms a continuous membranaceous indusium : the sporangia attached to an 

 uninterrupted transverse vein-like receptacle which connects the tips of the 

 forked and free veins. — Fronds 1 -3-pinnate or decompound. (The ancient 

 Greek name of Ferns, from Trrepoi/, a wing, on account of the prevalent pinnate 

 or feathery fronds.) 



1. P. aquilBlia, L. (Common Brake.) Frond dull green (2° -3° 

 wide), ternate at the summit of an erect stout stalk (l°-2°high), the widely 

 spreading branches 2-pinnate ; pinnules oblong-lanceolate, the upper undivided, 

 the lower more or less pinnatifid, with oblong obtuse lobes, margined all round 

 with the indusium. — Thickets and hills ; common northward. Aug. (Eu.) 



