This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Pine Family. Conifers. Resinous trees or shrubs, mostly with evergreen narrow entire or scale-like leaves, the wood uniform in texture, without tracheae, the tracheids marked by large depressed disks, the pollen-sacs and ovules borne in separate spikes (aments). Perianth none. Stamens several together, subtended by a scale; filaments more or less united; pollen-sacs (anthers) 2-several-celled, variously dehiscent; pollen-grains often provided with two lateral inflated sacs. Ovules with two integuments, orthotropous or amphitropous, borne solitary or several together on the surface of a scale, which is subtended by a bract in most genera. Fruit a cone with numerous, several or few, woody, papery or fleshy scales; sometimes berrylike. Seeds wingless or winged. Endosperm fleshy or starchy, copious. Embryo straight, slender. Cotyledons 2 or several.
About 25 genera and 240 species of wide distribution, most abundant in temperate regions.
Scales of the cone numerous (except in Larix); leaf-buds scaly.
Cone-scales thin; leaves linear-filiform, scattered or fascicled, not in sheaths.
Leaves fascicled on very short branchlets, deciduous.
Leaves scattered, persistent.
Cones pendulous; leaves jointed to short persistent sterigmata.
Leaves tetragonal, sessile.
Leaves flat, short-petioled.
Cones erect; sterigmata inconspicuous or none.
Scales of the cone few (3-12); leaf-buds naked.
Cone-scales spiral, thick; leaves deciduous-
Cone-scales opposite; leaves persistent.
Cone oblong, its scales not peltate.
Cone globose, its scales peltate.
Fruit fleshy, berry-like, a modified cone.