CONIFERALES (TAXACEAE) 321 



appears one-sided with its pendent abaxial sporangia; while in Cepha- 

 lotaxus the sporangia range from four to two in number. The site of 

 the three abortive sporangia in Torreya is occupied at maturity by a 

 large adaxial resin cavity, and in some cases six or seven mature 

 sporangia occur (98); whether there is such evidence of abortive 

 sporangia in Cephalotaxus has not been determined. This type of 

 stamen is very suggestive of that of the araucarians; and is represented 

 among the Cycadofilicales by the so-called Crossotheca or "epaulet" 

 type. Among the podocarps the stamens in general resemble those 

 of the Abietineae, two sporangia being borne on the abaxial face 

 of a bractlike sporophyll (sometimes, pendent?), whose sterile tip 

 is variously developed, from an inconspicuous point to a relatively 

 broad expansion. 



The details' of the development of the microsporangium have not 

 been followed, but at maturity the wall is three to five layers of cells 

 thick, the one or two innermost layers forming a somewhat inconspicu- 

 ous and short-lived tapetum. In Torreya taxijolia each sporangium 

 begins as a single hypodermal archesporial cell, which divides to form 

 the primary wall cell and the primary sporogenous cell. In the case 

 of the three abortive adaxial sporangia, their primary sporogenous 

 cells do not divide, but at this stage begin to break down, along with 

 the intervening sterile cells, and form the large resin cavity. 



The records of the winter condition of the microsporangia are too 

 meager to form the basis of a general statement, but Taxus cana- 

 densis in Chicago (51) and Torreya in England (98) pass the winter 

 in the mother cell stage. In Torreya taxijolia in Florida (loi), the 

 staminate strobili begin to be visible in June, the primordia of the 

 stamens begin to appear in August, the primary sporogenous cells 

 are recognizable early in September, the spores are in the shedding 

 condition in April, and fertilization occurs in August, making a period 

 of fifteen months from the first appearance of the staminate strobilus 

 to fertilization. It seems safe to conclude that this species also passes 

 the winter in the mother cell stage. 



THE MEGASPORANGIUM 



The ovulate strobilus is often so much reduced among the Taxaceae 

 as to lose the ordinary appearance of a strobilus; but in Saxegothaea 



