166 BOTANICAL GAZETTE [MARCH 
that the sporangium in both species passes the winter in the mother- 
cell stage, but that the subsequent stages appear earlier in T. tawijolia 
growing in its natural habitat than in 7. calijornica growing in Eng- 
land. For example, in the latter case the reduction division takes 
place about the time that 7’. taxifolia sheds its pollen, and pollination 
in T. californica does not seem to occur until late in May or early in 
June. | 
OOGENESIS. 
STROBILI.—The ovulate strobili are borne in the axils of the lower 
leaves of short young shoots (fig. 2). They usually occur in pairs 
upon a very short axillary branch, usually one pair, frequently two 
pairs, very rarely three pairs appearing upon a single shoot. A 
cluster of two to six strobili, therefore, appears near the base of the 
strobilus-bearing shoot, the upper pairs never maturing, usually 
one and sometimes both strobili of the lowest pair producing the 
large plum-like seeds (fig. 3). The strobilus is a very simple one, 
consisting of four enveloping bracts and a single terminal ovule with 
two integuments (figs. 17 and 78), the outer one often called an arillus 
because it ripens fleshy. The whole structure resembles a simple 
ovulate flower with a perianth of four bracts, which perhaps deserve 
to be called a perianth as much as the so-called perianth of Gnetales; 
but it is none the less evident that they are the sterile bracts of a much 
reduced strobilus. 
The strobili were first seen July 26, at which time the growing 
point, enclosed by the bracts, was composed of entirely homogeneous 
tissue, showing no differentiation as an ovule (fig. 17). No subse 
quent stages were found until April 7 (fig. 18), when the mother-cells 
were in synapsis (fig. 20); and it seems probable that the winter was 
passed in the mother-cell stage. At this time the integuments 47 
entirely free from the nucellus, appearing to arise from the base of 
the ovule. Soon, however, extensive intercalary growth below the 
mother-cell becomes evident, the ovule being greatly elongated and 
broadened below, the original free nucellus with its integumen 
forming only the tip. This growth continues throughout the season 
of fertilization and the following one; and Oxiver (6), who has 
described this intercalary growth in T. nucijera, estimates that ™ 
that species in the maturing seed the original nucellus with its free 
