[ 9 i S ] AASE—MEGASPOROPHYLLS OF CONIFERS 281 



The Abietineae and Podocarpineae have come from a common 

 primitive stock. The Abietineae are more advanced in the develop- 

 ment of the scale, but more primitive in holding on to a perfect 

 cone. ''The evidence at present is much in favor of the lycopodean 

 ancestry of the conifers." He has little faith in the brachyblast 

 theory, as it depends for its support mostly on abnormalities and 

 the vascular anatomy of the cone scales. "But abnormalities, 

 especially when they are supposed to be more or less of the nature 

 of reversions, afford by themselves unsatisfactory evidence of phy- 

 logeny." Vascular anatomy disproves the double nature of the 

 megasporophyll of the araucarians and podocarps, except in some 

 species in the latter, and there the compound structure is of recent 

 origin. 



Sinnott (4) in 1913 gave a very clear account of the strobilar 

 anatomy in a number of podocarps. He is of the opinion that the 

 podocarps and araucarians, along somewhat parallel lines of 

 development, have been evolved from ancient abietinean stock. 

 The scale in the Abietineae, the ligule in the araucarians, and the 

 epimatium in the podocarps are all homologous and vestiges of an 

 axillary shoot, and a simple sporophyll has arisen either by the 

 fusion of both of its parts or by the abortion of one. Of the podo- 

 carps he considers those most primitive in which the epimatium is 

 well developed and has a strong vascular supply, as Podocarpus; 

 and those most advanced in which there is a reduced epimatium, 

 as Dacrydium. In Podocarpus dacrydiodes there is a definite step 

 in the direction of Saxegot/iaea, Microcachrys, and Pherosphaera. 

 The resemblance in reproductive structures between certain mem- 

 bers of the Podocarpineae and Cephalotaxus, the most primitive 

 genus of the Taxineae, suggests that the latter family has arisen 

 from some ancient member of the Podocarpineae. 



Eames (i) in 1913, in a paper on Agathis, considered also the 

 megasporophyll situation in other conifer groups and concludes 

 that the megasporophyll is compound in origin in all Coniferales. 

 ''Even within themselves the Araucarineae show a complete series 

 from a form with strobilar units of a distinctly double nature to 

 one most simple through reduction.'' Eames has traced a similar 

 reduction in the Taxodineae. 



