CONIFERAE: THE SCOTS PINK 





bract-scale, bears on its upper surface a larger and thickened bl 



sometimes called the ovuliferous scale (Fig. 422). It seems probable 

 that this is a local upgrowth of tissue from the surface of the forn. 

 though as the cone grows older it becomes woody, and is by far the 

 more prominent feature of the two. Other interpretations of the 

 cone have been given ; but if this view be accepted, then the whole 

 cone is a simple flower bearing many complex sporophylls. Attached 



nc 



Fig. 423. 

 Median longitudinal section of an ovule of Picea excelsa at time of fertilisation. 

 * = embryo-sac filled with tissue of the female prothallus. a = archegoiuum. 

 showing venter (a) and neck (c). n = nucleus of ovum, nr = nucellus. />--pulkn- 

 grains. / = pollen-tube. » = integument. ( x 9.) (After Strasburger.) 



to the upper face of the ovuliferous scale are two ovules, which are 

 not enveloped by a carpel as in the Angiosperms. but are fully 

 exposed, with their wide micropyles directed downwards. Each ovule 

 consists of a nucellus corresponding to that of the Angiosper: 

 surrounded by a single integument, and with a wide micropyle 

 (m, Fig. 422). The pollen-grains being produced in enormous 

 numbers, and floating away on the dry air of a June day, are 

 scattered over the female cones, of which the scales then stand apart 

 to receive them. A drop of fluid extruded from the micropyle 



