Trees, with narrow or scale-like generally persistent clustered or alternate leaves and usually scaly buds. Flowers appearing in early spring, mostly surrounded at the base by an involucre of the more or less enlarged scales of the buds, unisexual, monœcious (_diœcious in Juniperus_), the male consisting of numerous 2-celled anthers, the female of scales bearing on their inner face 2 or several ovules, and becoming at maturity a woody cone or rarely a berry. Seeds with or without wings; seed-coat of 2 layers; embryo axile in copious albumen; cotyledons 2 or several. Of the twenty-nine genera scattered over the surface of the globe, but most abundant in northern temperate regions, thirteen occur in North America. CONSPECTUS OF THE NORTH AMERICAN GENERA. Scales of the female flowers numerous; spirally arranged in the axils of persistent bracts; ovules 2, inverted; seeds borne directly on the scales, attached at the base in shallow depressions on the inner side of the scales, falling from them at maturity and usually carrying away a scarious terminal wing; leaves fascicled or scattered (_deciduous in Larix_). Abietineæ. Fruit maturing in two or rarely in three seasons; leaves fascicled, needle-shaped in axillary 1—5-leaved clusters, inclosed at the base in a membranaceous sheath; cone-scales thick and woody, much longer than their bracts. 1. Pinus. Fruit maturing in one season. Leaves in many-leaved clusters on short spur-like branchlets, deciduous; cone-scales thin, usually shorter than their bracts. 2. Larix. Leaves scattered, linear. Cones pendulous, the scales persistent on the axis. Branchlets roughened by the persistent leaf-bases; leaves deciduous in drying; bracts shorter than the cone-scales. Leaves sessile, 4-sided, or flattened and stomatiferous above. 3. Picea. Leaves stalked, flattened and stomatiferous below, or angular. 4. Tsuga. Branchlets not roughened by leaf-bases; leaves stalked, flattened; not deciduous in drying; bracts of the cone 2-lobed, aristate, longer than the scales. 5. Pseudotsuga. Cones erect, their scales deciduous from the axis, longer or shorter than the bracts; leaves sessile, flat or 4-sided. 6. Abies. Scales of the female flowers without bracts; ovules and seeds borne on the face of minute scales adnate to the base of the