PAST HISTORIES OF PLANT FAMILIES gr 



scopic section show two rows or more of round bordered 

 pits. The cones are very large, but the male and female 

 are different in size and organization. The female cone 

 is composed of series of simple scales arranged spirally 

 round the axis, and each scale bears a single seed and a 



small ligule 



The pollen grains from the male cohe are caught on 

 the ligule and the pollen tubes enter the micropyle of the 

 ovule, bringing in passive male cells which may develop 

 in large numbers in each grain. The seeds when ripe 

 are stony, and some are provided with a wing from part 

 of the tissue of the scale. In the ripe cones the scales 

 separate from the cone axis. 



The Abietine^ are woody trees, some reaching a 

 great height, all with a strong main stem. The leaves 

 are of two kinds: primary ones borne directly attached 

 to the stem (as in first-year shoots of the Larch), and 

 secondary ones borne in tufts of two (in Pine) or a large 

 number (in older branches of Larch) on special short 

 branches, the primary leaves only developing as brown 

 scales closely attached to the stems. Leaves generally 

 very fine and needlelike, and with a central vascular 

 bundle. The wood in microscopic section shows a single 

 row of round bordered pits on the narrow tracheae. 



The female cones are large, male and female differing 

 greatly in size and organization. The female cone, com- 

 posed of a spiral series of pairs of scales, which often 

 fuse together as the cone ripens. Each upper scale of 

 the pair bears two seeds. The pollen grains from the 

 male cone enter the micropyle of the seed and are caught 

 in the tissue (apex of nucellus) there; the pollen tubes 

 discharge passive male cells, only two of which develop 

 in each grain. The seeds when ripe are stony and pro- 

 vided with a wing from the tissue of the scale on which 

 they were borne. 



The CuPRESSE/E are woody trees reaching no great 

 height, and of a bushy, branching growth. The leaves 

 are attached directly to the main stem, and arrange 



