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Class 1. GYMNOSPERMAE. Naked-seeded Plants. 



Ovules naked, inserted on the upper side of an open, mostly 

 flat, more or less developed scale, not enclosed in an ovary. Pollen- 

 grains divide into two or more cells, of which one produces a pollen- 

 tube; this fertilizes the ovule directly. All trees or shrubs, most 

 of them evergreen. 



Family 1. PINACEAE. Pine Family. 



Resinous trees or shrubs, mostly with evergreen, needle-shaped or linear 

 leaves. Stamens several together, subtended by a scale, forming elongated 

 aments; filaments more or less united; anthers usually 2-celled; pollen-grains 

 globose, ellipsoid, or lobed. Pistillate aments consisting of usually numer- 

 ous spirally disposed scales subtended by bracts.- Ovules inverted, usually 

 2 at the base of each scale. Fruit a dry cone. Seeds usually 2 at the base 

 of each scale, often samara-like; wing formed by a part of the scale. 



Leaves several together (in one species solitary), surrounded by a sheath at the base; 

 cones maturing the second year. 

 Cone-scales with dorsal, usually spLne-armed appendages. 



Seeds with elongated wings attached to the seeds when they fall; leaves mostly 



with two flbro- vascular bundles. 1. Pintjs. 



Seeds with narrow or rudimentary wings, which remain attached to the scales 

 when the seeds fall; leaves with a single flbro- vascular bundle. 



2. Cartopitts. 

 Cone-scales with inconspicuous terminal unarmed appendages. 



Seeds with rudimentary wings attached to the scales; cones subsessUe, spreading. 



3. Apinus. 



Seeds with well-developed wings, which remain attached to the seeds; cones dis- 

 tinctly stalked, pendulous. 4. Strobus. 

 Leaves not surrounded by sheaths; cones maturing the first year. 



Leaves in fascicles at the ends of short branches, deciduous. 5. L.uiix. 



Leaves scattered along the branches, persistent. 



Branches smooth, not roughened by persistent leaf-bases. 



Cones erect, their scales and bracts deciduous from the persistent axis; leaves 



sessile with circular leaf-scars. 6. Abies. 



Cones pendulous, their scales and bracts persistent; leaves petioled with trans- 

 versal oval leaf-scars. 7. Pseudotsuga. 

 Branches roughened by persistent leaf-bases (sterigmata) . 



Leaf-blades petioled with a single dorsal duct; anthers opening transversely: 

 seeds with re.sin- vesicles. 

 Leaves flat, with stomata only on the lower side, 2-ranked by twisting of 



the petioles; cones small, drooping. 8. Tsuga. 



Leaves not much flattened, keeled on the lower side, with stomata on both 

 sides, spreading in aU directions ; cones elongated, erect at least at first. 



9. Hesperopeuce. 



Leaf-blades sessile, with two lateral ducts, in ours 4-angled and spreading in 



all directions; anthers opening longitudinally; seeds without resin- vesicles. 



10. Picea. 



1. PINUS (Toum.) L. Hard Pines, Pitch Pines. 



Monoecious evergreen trees or rarely shrubs, with two kinds of leaves, the 

 primary leaves chaff-like, deciduous, the secondary ones green, needle-shaped, 

 usually with two fibro-vascular bundles (in all ours except in P. arislata), in 

 fascicles of 2-5, surrounded by a sheath, which is usually persistent. Staminate 

 aments elongated, at the ends of branches of the preceding year; anthers 2- 

 celled, opening longitudinally; pollen-grains 3-celled, the two lateral cells empty. 

 Pistillate aments globose or oblong, sessile or nearly so, below the terminal bud 

 or on the young twigs. Cones in ours subsessile, maturing the second autumn; 

 scales thick, spreading at maturity, with a dorsal appendage or thickening, 

 usually armed with a spine or at least a tubercle. Seeds samara-Uke, with the wing 

 remaining attached to the seed. 



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