pe Feo ee eet I Re en eee eee pe es eer a 27 client hime 
VOL. X11I. NO. 44.—BOTANICAL GAZETTE.—NOV., 1888. 
Development of cork-wings on certain trees, JI. 
EMILY L, GREGORY. 
ACER CAMPESTRE Linn. 
Two kinds of Acer were examined, one, A. campestre, con- 
spicuously winged till the stem is three or four years old, the 
other, 4. monspessulanum Linn., much less, though the early 
part of its periderm formation is very similar to that of A, 
campestre. ' development differs in both cases from that 
f Quercus, sufficiently, perhaps, to warrant a brief descrip- 
tion. 
f Acer campestre, the young stem is six-angled, the 
periderm forms uniformly around this, by the cells of the first 
ayer of primary rind becoming phellogen and developing 
centripetally!% just as in case of Quercus. e breaking = 
takes place along the six angles, the subsequently increased 
Tapidity of growth under these fissures occurs, but with this 
Veloped wi n each two successive ones 
ped wings, the clefts betwee The cells of 
a. : nis 
the Temaining epidermis have been so protected by thi 
tial wall is 
'’ Centripetal is in the sense that the newest tangential 
Dearest the hea .. reat here by Sanio, 
