CONIFERALES 289 



If any numbers can be said to be dominant, they are 12 and 24 for 

 the X and 2x phases of the hfe-history. At least 8 species of Pinus, 

 5 species of Larix, and 2 species of Podocarpus have these numbers. 

 GooDSPEED-''* found 12 and 24 in Sequoia gigantea; but Lawson^'''' 

 found 1 6 and 3 2 in 6*. sempervirens. In A hies halsamea''^^ the numbers 

 are 16 and 32; in Sciadopitys vcrticillata,^'*^ in Cephalotaxus drupa- 

 cea,^^^ 10 and 20; and in Taxus baccata,^""^ 8 and 16. The lowest num- 

 bers, 6 and 12, are reported by Saxton''^' for Callitris cupressoides. 



THE OVULATE STROBILUS 



Throughout, we have been using the terms "strobilus" and "cone" 

 almost synonymously. All cones are strobili; but not all strobili are 

 cones. The heading, the ovulate strobilus, is more appropriate than 

 the ovulate cone, because it includes the podocarps and taxads, some 

 of whose ovulate structures cannot be called cones, although we do 

 not hesitate to call them strobili. The spore-producing structure of 

 Lycopodium lucidulum is a strobilus, but not a cone. However, it rep- 

 resents a more primitive condition from which the typical cone of 

 Lycopodium clavatum could have been developed, with forms like 

 L. inundatum as intermediates. The term "cone" is shorter, and 

 throughout this work we have used it often, but only when either 

 term, "cone" or "strobilus," could be employed; and we have used 

 the more comprehensive term, "strobilus," when the term "cone," 

 would have been appropriate. 



In striking contrast with the simple staminate strobilus, the ovu- 

 late strobilus of the Coniferales is compound. The ovule-bearing 

 structures are not borne directly upon the cone axis, as in the stami- 

 nate cone, but in most cases are borne upon a much-discussed struc- 

 ture associated with a bract. This bract is borne directly upon the 

 main axis, and is homologous with the male sporophyll. As in the 

 staminate cone, the parts are formed in spiral succession, except in 

 the Cupressaceae and a few scattered genera in other families. 



Except in the Taxaceae and some of the Podocarpaceae, the ovu- 

 late strobili are cones, varying in size and appearance from the typi- 

 cal cones of Pinus to the small berry-like cones of Juniperus and 

 plumlike ovules of Torreya (figs. 292-96). 



Pinus and Araucaria have the largest cones. The longest ovulate 



