CONIFERALES (PINACEAE) 



245 



base, and two inverted basal ovules (figs. 270, 271). Among the 

 Taxodineae and Cupressineae there is a single bract or scale structure 

 with two distinct apices (dorso-ventral) at the free and enlarged end 

 and bearing one (Jimiperus) to many {Ciipressus) ovules. In 

 Juniperus this structure becomes fleshy in the organization of the 

 so-called "berry." Among the Araucarineae there is a prominent 

 bract, a ligule-like ovuliferous scale (present in Araucaria, wanting 

 in Agathis), and a single imbedded ovule some distance above the 

 base (figs. 272, 273). The discussion has centered about the nature 

 of the ovuliferous scale, and a brief outline of the development of the 

 subject will be of interest. 



Before 1827, in 

 which year Robert 

 Brown announced 

 gymnospermy (i), the 

 ovule was regarded as 

 a pistil, and the related 

 parts were variously 

 interpreted. Brown's 

 conclusion as to a 

 naked ovule was de- 

 rived from a compari- 

 son of the so-called 

 "ovule" (nucellus) of 



cycads and conifers with the ovule of angiosperms. His corollary 

 was that the ovuliferous scale is an open carpel, but his statement 

 that this so-called carpel is a leaf in the axil of a bract met strong 

 opposition. 



In 1839 ScHLEiDEN called attention (2) to the fact that Brown's 

 "folium in axilla folii" is a morphological impossibility, and that the 

 ovuliferous scale must be a flattened axis in the form of a placenta, 

 the axial nature of placentas in general being one of Schleiden's 

 peculiar views. This view of the branch nature of the ovuliferous 

 scale was concurred in later 'by Baillon, Dickson, Strasburger, 

 and Masters, but without regarding the axis as a placenta. 



In 1842 A. Braun (3) first advanced the theory that the ovuliferous 

 scale represents the first two leaves of an axillary shoot, which are 



Fig. 270. — Pi II us Laricio: diagram of ovule and 

 associated structures; b, bract; .9, ovuliferous scale; 

 V, vascular bundles; ;;/, micropyle; i, integument; 

 p, pollen grains; c, cavitj' in apex of nucellus; n, 

 nucellus; g, embryo sac. 



