1. Pinus L. (pine)
Leaves needlelike, in fascicles of 2–5 on highly condensed
“short shoots,” the fascicles with a papery basal sheath, this sometimes shed
as the leaves mature. Microstrobili ovoid to cylindrical, yellow. Megastrobili
conelike, woody, dehiscent, requiring 2–3 years to mature. Seeds winged
[lacking wings elsewhere], 1.5–3.0 cm long (including the wing), the wing
usually longer than the rest of the seed. About 100 species, North America,
Central America, Europe, Asia, Africa, Pacific Islands.
Pines are among the commercially most important timber trees of
North America. Although only Pinus echinata is native to Missouri, a variety of other species are grown in the state. Some of these, such as
ponderosa pine (P. ponderosa Douglas ex Lawson & C. Lawson), red
pine (P. resinosa Aiton) (Pl. 21g,h,i), and Scotch pine (P.
sylvestris L.), are grown only as ornamentals or on Christmas tree farms.
However, several other pines are commonly planted in timber plantations, for
wildlife habitat, and for erosion control. Such species frequently produce
cones and successfully reproduce within the populations, thus might be
considered to be naturalized locally. These are treated below in the interests
of completeness, although for the most part there is no evidence that the
plants ever disperse to new sites.