Leaf-fascicle and magnified
leaf-section.

12. PINUS STROBUS

1753 P. strobus Linnaeus, Sp. Pl. 1001.
1855 P. nivea Booth ex Carriere, Trait. Conif. 305.
1862 P. alba-canadensis Provancher, Fl. Canad. ii. 554.
1903 Strobus strobus Small, Fl. Southeast. U. S. 29.

Spring-shoots pubescent. Leaves from 6 to 14 cm. long, serrulate;
stomata ventral only; resin-ducts external. Cones from 8 to 24 cm. long,
narrow cylindrical, sometimes curved; apophyses fulvous brown, or rufous
brown, thin, the smooth or slightly rugose surface conforming to the
general surface of the cone; seed with a long wing.

A valuable timber-tree of singular beauty and rapid growth. The
northern limit of its range extends from Newfoundland to Manitoba; it
grows throughout the northern states from Minnesota to the Atlantic,
and, south of Pennsylvania, along the Appalachians to northern
Georgia. Its tractable and reliable wood, its adaptability to various
soils and climates, its early maturity and stately habit, recommend it
to the forester and gardener.

Mature trees of P. strobus tower above the evergreens associated with
it. It is also recognized by the color and horizontal massing of its
foliage. The cone, when closed, is very narrow; its thin flat scales
distinguish it from the cone of P. peuce, and its phyllotaxis from the
cone of P. monticola. To illustrate the possibilities of variation in
the size of Pine cones, I once collected several in Tamworth, N. H.,
on the estate of Mr. Augustus Hemenway, on the same slope and within
an area of one square kilometre. These cones varied in length from 6
to 24 cm., with all intermediate sizes. Also on each tree were cones
of various lengths, but the longest were confined to two or three
trees among the several hundred examined. Dimensions of leaves also
varied with individual trees; not infrequently the leaves of a tree
were twice the length of those of an adjacent tree. Such variations
appear in many species and in many localities.

Plate XII.

Fig. 119, Two cones. Fig. 120, Leaf-fascicle. Fig. 121, Magnified
leaf-section. Fig. 122, Conelets. Fig. 123, A cultivated tree in
Massachusetts.

[Illustration: PLATE XII. P. MONTICOLA (117, 118), STROBUS (119-123)]

=Paracembra=

Umbo of the cone-scale dorsal. Scales of the conelet mucronate or
aristate. Epiderm and hypoderm of the leaf similar, appearing as a
single tissue