CONIFERALES (TAXACEAE) 325 



the summer, tlie proembryo is formed during the autumn and ])asses 

 the winter, the embryo is completed during the next season, and the 

 seed is mature in the autumn. This involves two full years, from the 

 appearance of ovules to the maturity of the seed. Taxus (100) and 

 Cc phalotaxus (124) have approximately the same period, and the 

 first winter is passed in the mother cell stage. While the total period 

 in each of these three genera, which really constitute the taxads, 

 is approximately the same, its distribution among the various 

 events is strikingly different. In Torreya fertilization occurs 

 four months after pollination, and the seed is mature fourteen 

 months later; in Cephalotaxiis fertilization occurs fourteen months 

 after pollination, and the seed is mature four months later; while 

 in Taxus fertilization follows pollination in two months. The 

 only information concerning the podocarps, as yet, is that in 

 PhyUocladus (174) about a month intervenes between pollination 

 and fertilization. 



The current statements in reference to the integument among 

 Taxaceae are confusing, because of the appearance of a second or 

 outer integument, which arises considerably later than the inner one, 

 and which has been variously called outer integument, aril, and epi- 

 matium. In Torreya (loi) the outer integument develops the thick 

 fleshy covering of the seed, which gives it a pjlumlike appearance; 

 the inner integument differentiates into two layers, the outer of which 

 is the stony layer, and the inner consists of several layers of thin-walled 

 cells, distinctly differentiated only where the integument is free from 

 the nucellus. It is natural to see in these three layers the outer 

 fleshy, stony, and inner fleshy layers characteristic of the testa in 

 cycads. Ginkgo, and the older gymnosperms; and to conclude that 

 the two integuments have arisen from a single one, by delaying the 

 development of the region that becomes the outer fleshy layer. These 

 facts and the inference seem to hold good also in the case of Taxus, 

 the only difference being that the outer fleshy layer ("aril" in this case) 

 remains distinct from the inner one. In the case of PhyUocladus 

 (144), however, a different inference seems necessary; for the inner 

 integument differentiates into all three layers, the dift'erence being 

 that the outer fleshy layer is represented by only two layers of cells, 

 which are finally sloughed off. The outer integument arises late and 



