thern California, proves to be P. flexilis (Jepson,
Silva Calif. 74).

Plate VIII.

Fig. 90, Two cones and seed. Fig. 91, Leaf-fascicle. Fig. 92,
Magnified leaf-section.

[Illustration: PLATE VIII. P. KORAIENSIS (85, 86), CEMBRA (87-89),
ALBICAULIS (90-92)]

=II. FLEXILES=

Seeds wingless, the spermoderm forming a narrow border with a
rudimentary prolongation. Cones dehiscent at maturity.

The dehiscent cone distinguishes this group from the Cembrae.
Therefore confusion of P. koraiensis with P. Armandi, or P. albicaulis
with P. flexilis should be impossible. The peculiar seed is found
again only in the northern variety of P. ayacahuite.

Leaves usually entire, the stomata dorsal and ventral 4. flexilis.
Leaves serrulate, the stomata ventral only 5. Armandi.

4. PINUS FLEXILIS

1823 P. flexilis James in Long's Exped. ii. 34.
1882 P. reflexa Engelmann in Bot. Gaz. vii. 4.
1897 P. strobiformis Sargent, Silva N. Am. xi. 33, tt. 544, 545
(not Engelmann).

Spring-shoots pubescent; branchlets very tough and pliant. Leaves from 3
to 9 cm. long, entire, or serrulate in the southern variety, persistent
for five or six years; stomata dorsal and ventral or, in the south,
sometimes ventral only; resin-ducts external. Cones from 6 to 25 cm.
long, ovate or subcylindrical, short-pedunculate; apophyses pale tawny
yellow, or yellow ochre, lustrous, often prolonged and more or less
reflexed, thick, the margin together with the umbo raised above the
surface of the cone.

This species grows on the Rocky Mountains from Alberta in the Dominion
of Canada to Chihuahua in northern Mexico and ranges westward to the
eastern slope of the Sierras and to the southern mountains of
California. The wood, where accessible, is manufactured into lumber.
It may be seen in the Arnold Arboretum and in the Royal Gardens at
Kew.

P. flexilis is recognized by its lustrous yellow cones. This and the
constantly external ducts of its usually entire leaves distinguish it
from P. Armandi. From P. albicaulis, with similar leaves, it differs
by its dehiscent cone. At one extreme the cone of P. flexilis is not
unlike that of P. albicaulis, at the other extreme it approaches the
characteristic cone of P. ayacahuite, with prolonged reflexed scales.
Hence the confusion of P. albicaulis with P. flexilis (Murray,
Parlatore and others) and of P. flexilis with