1913] The Ottawa Naturalist. 99 



Onoclea Struthiopteris (L.) Hoffm. (Ostrich Fern), and 

 Onoclea sexsibilis L. (Sensitive Fern). The well known 

 Ostrich and Sensitive Ferns are almost invariablv found together, 

 and it seems impossible to differentiate between their habitats. 

 Their typical station is a moist clay or sandy loam in a locality 

 that is overflowed by spring freshets. Shade is not 

 an important factor if other conditions are favorable. The 

 most luxuriant growth of these ferns that the writer has found 

 was in Huron County. Here they were shaded by only a few 

 straggling willows. The ferns were associated with Virginia 

 creeper, Impatiens, wood nettle and turtle head. A spring creek 

 nearby would overflow the station in flood time. In " Ferns and 

 their haunts" W. N. Clute gives 0. Struthiopteris as, "at its best 

 in the wet, sandy soil of a half-shaded island or river shore." 



Woodwardia virginica (L.) Sm. (Chain Fern), and 

 Osmunda cixxamomea L. (Cinnamon Fern). May be considered 

 the peat bog ferns. Woodwardia is found growing in sphagnum 

 moss and extending out nearly to the edge of the lake that often 

 occupies the centre of the bog. It is associated with pitcher 

 plants and orchids, such as Calopogon, and only slightly shaded 

 by Ledum, Kalmia and Cassandra, with an occasional small 

 black spruce. In fact, shade is almost a negative factor. 



In a tvpical location examined the Osmunda formed an 

 outer zone in immediate contact with the preceding fern. Its 

 location, however, was drier and better shaded than that of 

 Woodwardia. The shade producing plants were hemlock, larger 

 black spruce and tamarack. Ledum, Cassaiulra and Kalmia 

 were also present, but these were not thriving as well as in the 

 inner zone. Occasional specimens of this fern are found also in 

 the moist, mucky soil of cedar swamps, but locations that furnish 

 peatv materials seem to be its natural habitat. 



Cystopteris bulbifera (L.) Bernh. (Bulblet Bladder 

 Fern), and Cystopteris fraoilis (L.) Bernh. (Fragile Bladder 

 Fern) have well differentiated habitats. C. bulbifera is sharply 

 marked out by the fact that spring water is an essential com- 

 ponent of its environment. As long as this factor is present, 

 others are not so important. As a consequence, it is found on 

 dripping rock ledges or springy clay in cedar swamps bordering 

 spring creeks, and in other habitats which present springy 

 conditions of soil. Drainage is here a very important factor, 

 as stagnant water does not present the proper conditions. 

 Aspidium Thelypteris and Onoclea are not nearly so sensitive in 

 this respect. One tvpical station examined presented the fern 

 associated with Indian turnip and enchanter's nightshade near the 

 base of a ridge with a decidedlv springv soil. Another station 



