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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
This led him to make a study of the germination in a num- 
ber of species of oaks. He noted the fleshy cotyledons, the 
“little caulicle, and at the upper end, toward the center of the 
acorn, the two stalks or petioles of these cotyledons.” The plu- 
mule is hut slightly developed. These structures vary some- 
what in different species. In the black oaks ( Q . nigra), etc., he 
found that the stalks are longer than the caulicle. In Q. macro- 
car pa-, Q. Ro'bur and Q. chrg solepis , the caulicle is nearly three 
times as long as the stalk. In the majority of white oaks (Q. 
alba, Q. stellata), etc., the caulicle is shorter than the stalks 
of the cotyledons. The longer stalks are found in Q. virginiana. 
Sargent 5 gives the following general description of the germina- 
v tion of the acorn : 
The radicle is imbedded near the apex of the seed between 
the fleshy cotyledons with the minute plumule or growing point 
between thin petioles toward the middle e»f the seed ; the radicle 
in the North American black oaks and in a few of the white 
oaks being longer than the petioles of the cotyledons, and shorter 
in most of the white oaks. In germination the petioles of the 
cotyledons with the plumule, lengthen pushing the plumule 
outside the cracked shell of the nut within which the cotyledons 
remain ; the plumule develops into the ascending axis of the 
plant, which is covered in its lower nodes with minute scales, 
and is nourished by the food contained in the cotyledons, which 
rot and disappear toward the end of the first season after the 
radicle, by absorbing some of their nutritious material, has be- 
come swollen and enlarged. 
That the cotyledon may furnish food supply for the second 
season, is stated by H. Marshall Ward: 
The two cotyledons remain inclosed in the coats of the acorn ; 
the developing root obtains its food materials from the stores 
in the cells of the cotyledons, as do all the parts of the young 
seedling at this period. In fact- these stores in the cotyledons 
contribute the support of the plant for many months, and even 
two years may elapse before they are entirely exhausted. 
Sir John Lubbock 6 describes the germination of two European 
'Species, e. g. the Q. Robur var. pedunculata and Q. Ilex. These 
species are said to be very similar in their germination. Like all 
oaks the germination is hypogaeous, the primary leaves are re- 
duced to scales, and the hypocotvl soon becomes woody ; the cau- 
5 The S'ilva of North America, 8, .2, 4. 
Contribution to our knowledge of seedlings, 534, London, 1892. 
