"Pines are recognized by their resinous wood and their needle-like leaves which are found in bundles of 1 to 5 and enclosed at base in a papery sheath which may be, sooner or later, deciduous.
The male flower is a long catkin usually grouped with several others on a terminal twig. Each cluster of stamens is surrounded at base by 3 to 6 scales. When ripe the anthes are bright yellow with abundant, buoyant pollen. The female flowers, found on last year's shoots, form short thick catkins furnished with papery bracts which soon disappear, and larger persistent fleshy scales which become the woody scales in the mature cone. At flowering time the scales of the female conelet open wide and recieve the wind-borne pollen.
When pollinated, they close again and do not open until the seed is ripe, or in some cases until years afterward. About one year after pollination, fertilization takes place within the ovules, and the conelet, which has changed little till now, begins a period of rapid growth. The exposed tip of each cone scale is usually more or less thickened and shows the apex of the first season's growth in a scar or protuberance which is frequently provided with a prickle and transversely ridged with a keel."
"This would seem a poor method (seeds fall to the ground in autumn) of distribution, but there is at hand a vicarious one. For hosts of Clark nutcrackers come every year, with their harsh, rolling cries of churrrr, churrr.
With mighty beaks these gray crows thrash open the green cones and extract the seeds."
Donald Culross Peattie