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. | ||
1. | Pinus. | |
Cone-scales thin; leaves linear-filiform, scattered or fascicled, not in sheaths. | ||
Leaves fascicled on very short branchlets, deciduous. | 2. | Larix. |
Leaves scattered, persistent. | ||
Cones pendulous; leaves jointed to short persistent sterigmata. | ||
Leaves tetragonal, sessile. | 3. | Picea. |
Leaves flat, short-petioled. | 4. | Tsuga. |
Cones erect; sterigmata inconspicuous or none. | 5. | Abies. |
Scales of the cone few (3-12); leaf-buds naked. | ||
Cone-scales spiral, thick; leaves deciduous- | 6. | Taxodium. |
Cone-scales opposite; leaves persistent. | ||
Cone oblong, its scales not peltate. | 7. | Thuja. |
Cone globose, its scales peltate. | 8. | Chamaccyparis. |
Fruit fleshy, berry-like, a modified cone. | 9. | Juniperus. |
 
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