HOFFMANN: FLORA OF BERKSHIRE COUNTY. 197 



Alluvial soil along rivers and brooks to an altitude of 1500 ft.; 

 common. 



PTERIDIUM. Brake; Bracken. 

 {Pteris Man. ed. 7; vid. Rhodora, 21: 176, 1919.) 



P. latiusculum (Desv.) Maxon. Common Brake. — (Pteris 

 aquilina Man. ed. 7; Pteridium aquilinum III. Fl. ed. 2.) 



Borders of woods, open woodland, rocky upland pastures and 

 clearings; common. 



THELYPTERIS. Shield Fern. 



(Aspidium Man. ed. 7; Phegopteris Man. ed. 7; Dryopteris 111. Fl. ed. 2; irid. 

 Rhodora, 21: 174, 176, 1919.) 



T. Boottii (Tuckerman) Nieuwl. Boott's Shield Feen. — 

 Swampy woods; frequent. Perhaps a hybrid between Thelypteris 

 cristata and T. spinulosa, var. intermedia. Specimens collected in 

 Washington by C. S. Lewis have the later fronds with laciniate seg- 

 ments, apparently due to the presence of a borer in the rootstock. 



T. cristata (L.) Nieuwl. Ceested Shield Fern. — Borders of 

 swampy woods and low meadows; frequent. 



var. Clintoniana (D. C. Eaton) Weatherby. Clinton's Shield 

 Fern. — (D. Clintoniana 111. Fl. ed. 2.) 



Swampy woods; frequent in the valley, occasional on the plateau. 



T. Dryopteris (L.) Slosson. Oak Fekn. — Cool woods, often 

 under conifers; frequent. 



T. Goldiana (Hook.) Nieuwl. Goldie's Shield Fern. — Rich 

 woods, generally in alluvial pockets spread by brooks at the bases of 

 slopes of rich soil, often in company with Athyrium angustifolium; 

 occasional in the valley. Florida (Hunnewell); Williamstown 

 (Churchill); Cheshire (Winslow); Lanesboro (Churchill); Pittsfield; 

 Washington (C. S. Lewis) ; Lenox; Stockbridge; Sheffield (Walters). 



T. hexagonoptera (Michx.) Weatherby. Broad Beech Fern. — 

 Rich moist soil in rather open woodland; occasional in the valley. 

 Williamstown (Churchill) ; Hancock (Churchill) ; Lenox; Stockbridge; 

 Great Barrington; Sheffield. 



T. marginalis (L.) Nieuwl. Marginal Shield Fern. — Rocky or 

 swampy woods, often on rocks; common. 



forma elegans (Robinson) Weatherby, comb. nov. — {Asjddium 



