Moss-like plants with branching stems and scale-like leaves which are many ranked and uniform, or 4-ranked and of two types spreading in two planes. Sporanges solitary in the axils of the leaves which are so arranged as to form more or less quadrangular spikes. [Sidenote: =Selaginella selaginoides= (L.) Link. _Low Selaginella._] Sterile stems, prostrate and creeping, small and slender; fertile stems thicker, ascending, simple 1—3 inches high; leaves lanceolate, acute, spreading, sparsely spinulose-ciliate; spikes solitary at the ends of the fertile branches, bracts lax, ascending lanceolate or ovate-lanceolate, strongly fringed. A light green moss-like plant growing in wet sandy grounds in the Rockies; not infrequent. [Sidenote: =Selaginella densa= Rydb.] Densely tufted sterile branches very short and crowded; leaves, densely crowded, many-ranked linear or needle-shaped in age, slightly flattened and grooved on the upper side, the margin fringed, tipped with a white bristle; fertile branches erect, the spikes quadrangular ½—¾ of an inch long, bracts folded together, thick, triangular-ovate, fringed on the margin and tipped with a white bristle half as long as that of the leaves. In sterile dry ground and on exposed rocks throughout the region from the bases to the tops of the highest mountains, forming grayish-green mats on the ground. PINACEÆ. _Pine Family_ Resinous trees and shrubs mostly with evergreen, narrow, entire or scale-like leaves; the pollen sacks and ovules borne in separate spikes; fruit a cone with numerous, several or few, woody, papery or fleshy scales, sometimes berry-like; seed wingless or winged. Scales of the fruit numerous, alternate; leaf-buds scaly. Leaves in clusters. Clusters ensheathed at the base, containing 2, 3, or 5 leaves. =Pinus.= Clusters not ensheathed at the base containing many leaves. =Larix.= Leaves solitary. Cones erect; scales deciduous. =Abies.= Cones pendent; scales persistent. Branchlets smooth; bracts 3-toothed. =Pseudotsuga.= Branchlets roughened by the persistent leaf bases. Leaves petioled, not pungent. =Tsuga.= Leaves sessile, pungent. =Picea.= Scales of the fruit few, opposite; leaf-buds naked. Fruit fleshy and berry-like. =Juniperus.= Fruit a dry cone. =Thuja.= [Sidenote: =Pinus albicaulis= Engelm. _White-bark Pine._]