118 CONIFERALES (RECENT) 



often very gradual in contrast to the much more sharply denned 

 break between leaves and scales in most of the Abietineae and 

 many other Conifers. The cone-scales of the Abietineae are 

 recognised as more complex and more recent developments, the 

 seminiferous scale being an excessively enlarged placental out- 

 growth from a megasporophyll, while in the intermediate types 

 such as Sequoia, Cryptomeria, and others the separation between 

 the two parts of the cone-scale is much less complete 3 . This 

 morphological question is too complex to discuss fully in a 

 general summary : students should, however, be warned that 

 several botanists do not agree with the opinion that is here 

 expressed. It is at least fair to add that the views expressed 

 by Prof. Jeffrey and his pupils with regard to the relative positions 

 of the Araucarineae and the Abietineae in an evolutionary series 

 are stated with an assurance which is misleading to those unfamiliar 

 with the nature of the evidence 2 . 



In Saxegothaea (fig. 685), Dacrydium (fig. 684, P), and some other 

 genera each ovule is surrounded by a cup-like integument (fig. 684, 

 T a), formerly called the arillus but recently styled the epimatium 3 ; 

 this' is by some authors considered to be the equivalent of the 

 seminiferous scale. 



This inadequate account may serve to call attention to a complex 

 morphological problem which has an important bearing on questions 

 connected with the relative positions of the several genera. It would 

 be out of place to enter fully into this difficult subject, but it is one 

 that demands careful attention by students of extinct types. 



The number of seeds borne on each scale is an important 

 feature in the recognition of genera. In the Abietineae each 

 scale usually bears two seeds though it is not uncommon to find 

 single-seeded seminiferous scales such as those of Pinus monophylla 

 (fig. 686, A C) in which there is a deep cavity showing that the 

 seed was partially embedded in the supporting organ. Such a 

 scale might, as a fossil, be easily mistaken for an Araucarian cone- 

 scale. In Cunninghamia there are three seeds to each scale (fig. 

 684, K) ; in Athrotaxis and Cryptomeria 3 6 ; in Sequoia 5 ; and 



1 Eichler(81). 



2 For a recent discussion on the origin and relationship of the Araucarineae see 

 Burlingame's paper (15 2 ) which ap'peared after this chapter was written. 



3 Pilger (03) p. 16. 



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