en closed,
cones. It is associated with P. caribaea and, in the northern part of
its range, it grows with the other Southern species. By its close
resemblance it may be considered the serotinous form of P. virginiana.

Plate XXXIII.

Fig. 288, Three nodal groups of cones of the same year. Fig. 289,
Conelet and its enlarged scale. Fig. 290, Leaf-fascicle and
magnified leaf-section. Fig. 291, Larger form of the tree.

[Illustration: PLATE XXXIII. P. VIRGINIANA (284-287), CLAUSA (288-291)]

54. PINUS RIGIDA

1768 P. rigida Miller, Gard. Dict. ed. 8.
1909 P. serotina Long, in Bartonia, ii. 17 (not Michaux).

Spring-shoots multinodal. Leaves ternate, from 7 to 14 cm. long;
resin-ducts medial, or with an occasional internal duct, hypoderm
biform. Scales of the conelet abruptly prolonged into a spine. Cones
from 3 to 7 cm. long, ovate-conic, symmetrical, persistent, dehiscent at
maturity or rarely serotinous; apophyses lustrous tawny yellow, elevated
along a transverse keel, the umbo salient and forming the broad base of
a slender sharp prickle.

A tree with bright green foliage in spreading tufts. The northern
limit of its range is in southwestern New Brunswick, southern Maine,
central New Hampshire and Vermont, the Thousand Islands of the St.
Lawrence River and central Ohio. It ranges into Pennsylvania and
Delaware at low levels and thence over the Alleghanies into northern
Georgia. It is associated with P. strobus and P. resinosa and, further
south, with P. virginiana. The cones are rarely serotinous, but it is
remarkably like P. serotina in many characters, and is therefore
placed in this group.

Plate XXXIV.

Fig. 292, Cones. Fig. 293, Leaf-fascicle, magnified section through
a fascicle, and magnified dermal tissues of the leaf. Fig. 294,
Upper part of a tree.

55. PINUS SEROTINA

1803 P. serotina Michaux, Fl. Bor. Am. ii. 205.

Spring-shoots multinodal. Leaves ternate, from 12 to 20 cm. long;
resin-ducts medial or medial and internal, hypoderm biform. Conelet
long-mucronate. Cones from 5 to 7 cm. long, subglobose or short-ovate,
symmetrical, persistent, serotinous; apophyses lustrous tawny yellow,
slightly elevated along a transverse keel, the umbo forming the broad
base of a slender, rather fragile prickle.

This species is confined to low wet lands from southeastern Virginia
to northern Florida and central Alabama. It is one of