HOFFMANN: FLORA OF BERKSHIRE COUNTY. 279 



A hybrid between T. cordifolia and Mitella diphylla has been col- 

 lected in Williamstown by Sanborn Tenney {vid. Rhodora, 8: 91, 

 1906). 



HAMAMELIDACBAE. WITCH-HAZEL FAMILY. 



HAMAMELIS. Witch-hazel. 



H. virginiana L. Witch-hazel. — Woods; common in the val- 

 ley, becoming rare on the plateau. Reaches an altitude of 2000 feet 

 in Savoy. 



PLATANACEAE. PLANE TREE FAMILY. 



PLATANUS. Sycamore; Buttonwood; Plane Tree. 



P. occidentalis L. Sycamore; Buttonwood. — Flood-plains; 

 common in the valley. 



ROSACEAE. ROSE FAMILY. 



AGRIMONIA. Agmmont. 



A. gryposepala Wallr. — Open woods, clearings and roadside 

 thickets; common. 



A. striata Michx. — Low ground and moist open woods'; common. 



AMELANCHIER. Shadbush; JuVteberrt; Service Berry. 



Key to Amelanchier. 

 a. Flowers racemose. 

 b. Teeth of the leaves coarse (on average leaves 3 to 5 (6) per cm.); veins 

 conspicuous, usually straight, parallel and close together; leaves oval 

 to oval-oblong, rarely orbicular; scrawny, slender, often arching 



shrub of a few rocky mountain-tops A. sanguinea. 



b'. Teeth of the leaves fine (5 to 12 per cm. on average leaves) ; veins irregu- 

 lar, unequally distant, usually with frequent intermediate shorter ones. 

 c. Leaves densely white-tomentose when young, becoming green ; lower 

 pedicels 7 to 18 mm. long, in fruit 10 to 25 mm. long. 

 d. Leaves rounded at the apex; petals short, 7 to 9 mm. long; 3 to 12 

 dm. high; stiffly upright shrubs forming patches. Shrub of 

 rooky mountain-tops or sandy plains in the southern part of the 



valley A. stolonifera. 



d'. Leaves short acuminate, petals usually elongated, 10 to 14 mm. long. 

 Flowers appearing very early, usually before the leaves. Shrub 

 or tree, generally solitary, or few together, widely distributed. 



A. canadensis. 



