VIII. 2. THE FROST OR TENDER WILLOW. 261 
found more plentifully in higher northern latitudes. It seems, 
indeed, to possess all the fitting requisites for enduring a severe 
climate; and affords a beautiful exemplification of nature’s 
economy, in the structure of the catkins of the willow, provid- 
ing those exposed during flowering time to severe cold, with a 
vesture which outvies the imperial ermine.”’~—Barratt. 
Sp. 7. Tse Frost or Tenner Wittow. S. sensitive. Barratt. 
Leaves ovate-lanceolate, acuminate; cuneate and entire at the base, finely 
serrate at the point, and more distantly and strongly serrated towards the 
base; leaves three to five inches long, one and a half to two inches wide ; 
glabrous ; above deep green, beneath smooth and pale green, and of a thinnish 
texture. Stipules subfalcate, serrate. Mas. aments rather lax, one and a half 
inches long; scales lanceolate, black, lightly clothed with grayish black hairs. 
Aments and flowering branches frequently destroyed by frost.—Barrait. 
Flowers April 1—10. 
‘* A small tree about fifteen feet high. 'This species has not 
hitherto been described. It bears large, smooth leaves with 
greenish branches. ‘The aments and twigs are frequently de- 
stroyed by frost in flowering time. When it has been thus 
killed, the aments and branches blacken, afterwards some scat- 
tering flowers appear, but these are generally of inferior size. 
“The twigs of S. sensitiva, at their extremities, have but a 
slight velvety pubescence to protect them; and the aments are 
sparingly clothed with hairs. It offers a striking contrast to 
S. crassa, with its dense, woolly catkins, which are uninjured 
by the frosts to which they are exposed during the period of 
flowering. When the catkins of S. sensiiva begin to expand, 
on the approach of the flowering season, the large scales of the 
buds, or shields, covering the aments, fall, or when these are 
purposely removed for observation, the aments present a lively 
red color. ‘The direct solar ray soon changes the scales of the 
aments to black, (very similar to the action of nitrate of silver, 
when exposed to light, but less rapid.) The hairs of the ament 
are, also, changed to a blackish gray. An attentive observance 
of this and some other willows, has satisfied me, that the hairs 
or clothing of the scalés of the catkins, besides protecting them 
from frost, perform in this and other groups, a function similar 
