186 MACOUN AND BURGESS ON 



Phorobolus acrostichoides, Fee. 



The Rock-Brake grows from 4 to 12 inches high, and forms dense tufts among rocks 

 and in their crevices. It is a handsome species, with evergreen barren fronds. Rootstocks 

 creeping and chaffy ; stalks numerous and straw-coloured, bearing fronds of two kinds; 

 sterile fronds ovate in general outline, dark green, smooth, leathery, short-stalked, bi-quad- 

 ripinnatifid, with ovate or obovate, toothed ultimate segments ; fertile fronds more lance- 

 olate in general outline, thinner, yellowish, long-stalked (standing nearly twice as high 

 as the sterile), less compound, with narrow linear or linear-oblong segments ; indnsia 

 formed of the edges of the segments, which are so far reflexed as to meet at the midrib 

 and thus give them a pod-like appearance. 



Occasionally, in this fern, the upper part of a fertile frond is sterile, and Mr. Daven- 

 port, in the " Botanical Gazette," has reported specimens with the lower pinnae sterile. 

 Some sterile fronds from British Columbia show the ultimate segments lanceolate or almost 

 linear-lanceolate, and very regularly and sharply serrate, while in others the fertile 

 pinnules are remarkably long and narrow, the basal ones in some cases measuring nearly 

 one inch in length by only half a line in width. 



With us this plant is found from Lake Huron west to British Columbia, extending 

 northward to within the Arctic Circle. McLeod's Harbour, Manitoulin Islands, Ont. — J". 

 Bell. Cumberland House to Great Bear Lake, N. W. Ter. — Richardson. Between Echim- 

 amish River and Oxford House, and around Cross Lake and Nelson River, near Hudson 

 Bay, N. W. Ter. — R. Bel/. Stony places in the Rocky Mountains, but rare, to the sources 

 of the Columbia River, B. C. (Drummond), thence to the Grand Rapids of the Columbia 

 (Douglas), in Hook., Fl. Bor.-Am. Rocks along the Arctic coast, from Mackenzie River 

 to Baffin Bay. — Hook., Arc. PI. Kicking Horse Pass, Rocky Mts., N. W. Ter.; common in 

 the Cascade range, and along the Fraser River, B. C. — Macoun. Yale, B. C. — /. Fletcher. 

 Wigwam River, Kootauie Valley, Rocky Mountains. — G. M. Dawson. 



Genus VI.— PTERIS, L., Brake or Bracken. 



1. — P. aqtjilina, L., (Common Brake or Bracken, Eagle-Fern), Mx, Fl. Bor.-Am., II, 

 262. Swartz, Syn. Fil., 100. Gray, Man., 658. Provancher, Flor. Can., 715. Lawson, Can. 

 Nat., I, 270. Hook, and Baker, Syn. Fil., 162. Macoun's Cat., No. 2291. Fowler's N. B. 

 Cat, No. 746. Ball, Trans. N. S. Ins. Nat. Sci, IV, 149. Watt, Can. Nat, IV, 363. Eaton, 

 Ferns of N. A., I, 263. Underwood, Our Nat. Ferns, etc, 88. 



Allosorus aquilinus, Presl. 



This is the coarsest and one of the commonest of our native ferns, growing from 1 to 

 5 feet high. It is non-evergreen, though in sheltered situations it stands a good deal of 

 frost, and, while commonest on dry, sunny hillsides, is also found in thickets and even in 

 wet, thick woods. Rootstock black, widely creeping at usually a considerable depth 

 underground, producing only one frond each year, but having the scattered, woody re- 

 mains of the stalks of several previous years attached ; stalks light-brown,, rigid, naked, 

 the part between the rootstock and the point where they emerge from the ground swollen 

 and darkened; fronds dull green, leathery, triangular in general outline, varying from a 

 foot, or even considerably less, to three feet in length by nearly as much in breadth, 

 upper surface smooth, the lower slightly pubescent, bi-tripinnate ; principal primary 



