BRIEFER ARTICEES 
THE MICROSPOROPHYLLS OF GINKGO 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 134 
(WITH PLATE VII) 
This study was undertaken in the first place to determine the origin of 
the mucilage ducts in the hump of the microsporophyll.. As there is a 
general resemblance among the microsporophylls of Taxus, Torreya, and 
Ginkgo, and as in Torreya, according to CouLTER and Lanp? (p. 163), 
the resin ducts are formed from the disorganization of three of the seven 
sporangia, it seemed possible that in Ginkgo the mucilage ducts might have 
been formed from abortive sporangia also. As my material showed the 
development of the strobili and microsporangia, I have included an account 
of them, so as to give a general history of the development of the microsporo- 
Phyll. The buds were collected during July, August, and September of 
1907 from a tree in Elyria, Ohio, in grounds then owned by Mr. I. W. MeEt- 
CALF. Thanks are due him for the material and also Professor F. O. 
GROVER of Oberlin College and Mr. Frep Stoxey for collecting. 
Development of the strobili 
The strobili which will mature pollen the following year are formed in 
June or early July, but are hidden in buds which cannot be distinguished 
from leaf buds. In the latter part of July, if the scale leaves are removed 
rom the buds, the strobili can be seen as small papillae in the axils of the 
scale leaves. Examined with a microscope, strobili of the same bud often 
Show different stages of development, some being short, with the sporophylls 
nee evident as small rounded elevations (jig. 1), others being elongated cones 
with the lower sporophylls beginning to show differentiation into sporoge-~ 
egy part and hump (fig. 2). The development of the two sides of the stro- 
bilus is often very uneven, due to greater crowding on one side than on the 
other. At this stage there is no differentiation of tissue in the sporophylls 
“ the top of the strobilus, but in those lower down mucilage ducts are begin- 
ning to form in the most external portion of the sporophylls; and in sporo- 
ery Ils a the base the ducts are fully formed and functioning sporogenous 
wi beginning to be evident in the part nearest the axis. Occasionally 
bee Pisa Joun M., anv Lanp, W. J. G., Gametophytes and embryo of Torreya 
* BOT. GAZETTE 39:161-178. pls. A, I-3. 1995. 
s {Botanical Gazette, vol. 49 
