. Fig. 129, Magnified leaf-section.

15. PINUS NELSONII

1904 P. Nelsonii Shaw in Gard. Chron. ser. 3, xxxvi. 122, f. 49.

Spring-shoots slender, pruinose; branchlets very pliant and tough,
summer-shoots abundant. Leaves with a persistent sheath, from 6 to 9 cm.
long, united in threes along a portion of their ventral surface into
pseudomonophyllous fascicles, serrulate on the two margins of the dorsal
surface, entire on the ventral margin; stomata dorsal and with one row
along the free portion of each ventral face. Conelets usually, if not
always, pseudolateral by reason of the summer growth of the branchlets,
and attaining in their first season an unusually large size. Cones from
6 to 12 cm. long, on very long stout and curved peduncles, cylindrical,
deciduous by an articulation between the cone and its peduncle, leaving
the latter for several years on the tree; apophyses dark lustrous
orange-red, rugose, elevated along a sharp transverse keel, the umbo
obscurely defined, the mucro usually broken away; nuts large, flaxen
yellow, the spermoderm adnate to the cone-scale.

A small bushy tree with long pliant branches, clear gray cortex all
over the limbs and trunk, and sparse gray-green foliage. It grows,
together with P. cembroides, on the lower slopes of the northeastern
Sierras of Mexico, near the boundary between the states of Tamaulipas
and Nuevo Leon. It is apparently confined to a small area near the
latitude of the city of Victoria, the capital of Tamaulipas, where its
nuts are often exposed for sale.

In many characters this species is unique. It can be recognized at
once by the connate leaves that form the fascicle or by the remarkable
stout curved peduncle of its cone. Such seeds as I have seen differ
from those of P. cembroides by a reddish area at one end, but this can
be seen with fresh seeds only.

Plate XIII.

Fig. 124, Cone, cone scale and seed. Fig. 125, Branchlet with
leaves. Fig. 126, Magnified section of a leaf-fascicle.

[Illustration: PLATE XIII. P. NELSONII (124-126), PINCEANA (127-129),
CEMBROIDES (130-132)]

=V. GERARDIANAE=

Seeds with a very short ineffective articulate wing. Leaves in fascicles
of 3, serrulate, the sheath deciduous. Bark exfoliating in large scales,
leaving parti-colored areas.

These Asiatic Nut Pines are alike in leaf and cortex as well as in the
peculiar seed-wing. The last often remains in the cone after the nut