CONIFERALES 



281 



bracts; consequently, the staminate strobilus is a flower, not an in- 

 florescence. The ancient discussion as to whether the ovulate stro- 

 bilus is a flower or an inflorescence will be considered later. 



The cones vary greatly in size. The cone of Juniperus communis, 

 2 mm. in length, with nearly mature pollen, but before the rapid 

 lengthening which allows the pollen to be 

 shed freely, is very small; while the cone 

 of Araucaria hidwilli, 10 cm. in length, is 

 extremely large. It is claimed that this 

 cone reaches a length of 20 cm. Dr. 

 George Graves of Fresno, California, 

 where there are scores of fine large trees 

 of this Australian species, has collected a 

 few cones 12.5 cm. in length, but has never 

 seen any approaching the reputed 20 cm. 

 In Araucaria riilei it is reported that cones 

 reach a length of 24 cm. In Araucaria cun- 

 ninghami the cones have a greater diameter 

 and reach a length of 7 cm. before the rapid 

 lengthening begins. They occur in immense 

 numbers and produce a prodigious amount 

 of pollen (fig. 286). It would not be exag- 

 gerating to estimate the output of a single 

 cone at 10,000,000 pollen grains. 



The origin of sporophylls from the meri- 

 stemisdominantly spiral, the Cupressaceae 

 being the only family which shows the cy- 

 cHc arrangement throughout. The arrange- 

 ment of sporophylls, however, is so geo- 

 metrically regular that they often seem to 

 be in vertical rows, as they would be if the 

 arrangement were cyclic (figs. 284 and 285). 



The sporophylls, like the cones, vary greatly in size (fig. 287). The 

 figure shows typical sporophylls of ten genera. Some of the pines 

 have smaller sporophylls than Pinus laricio; and it is possible that 

 some species of Araucaria may have larger sporophylls than A, cun- 

 ninghami; but the figure, with all the sporophylls drawn to the same 



Fig. 284. — Pinus contorta: 

 shoot with a large number of 

 axillary staminate cones. The 

 a.xis of the shoot is prolonged 

 beyond the cones, and, at the 

 base, shows pairs of needles 

 nearly covered by bracts; 

 higher up, the needles are en- 

 tirely covered by the bracts. 

 Although the sporophylls ap- 

 pear to be in vertical rows, 

 their arrangement on the cone 

 is strictly spiral; natural size. 



