
Vascular Flora of the Southeastern United States
Hardin, Massey, Radford, Thieret, eds.
Copyright - James W. Hardin, Ph. D., 1998, 1999. All Rights Reserved.
PINACEAE THE PINE FAMILY
Evergreen or deciduous, monoecious, resinous trees. Leaves acicular (needle-like) or linear, alternate on long shoots, and in some genera, clustered on indeterminate or determinate short shoots. Pollen cones simple, clustered, with spirally arranged microsporophylls each with abaxial sporangia, dropping after pollination. Ovulate or
seed cones compound, with thin, spirally arranged bracts, each subtending a thicker scale bearing 2 ovules adaxially near the base. Mature seed cones more or less woody, the seeds with a terminal wing. This is one of our most economically important families for lumber, paper pulp, and turpentine products.
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1 Dwarf branches (short-shoots) produced; leaves on older branches either
in fascicles or on lateral spur branches; leaves acicular (needle-like).
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2 Leaves 4 cm or more long, persistent, 2-5(6) borne on determinate short-shoots
(fascicles)..... 1. Pinus.
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2 Leaves 4 cm or less long, deciduous after one season, borne individually
but crowded and numerous on indeterminate short-shoots..... 2.
Larix.
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1 Dwarf branches (short-shoots) lacking; all leaves borne individually
on long-shoots; leaves linear.
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3 Seed cones erect; cone scales deciduous from the persistent central axis;
leaves sessile, persistent on dry branches, leaving a smooth, round scar
when separating..... 3. Abies.
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3 Seed cones pendent, cone dehiscing as a unit; leaves sessile or petioled
on pegs, readily separating and leaving the persistent, decurrent pegs.
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4 Leaves square in cross section, sessile on a peg..... 4. Picea.
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4 Leaves flat in cross section, petioled on a peg..... 5. Tsuga.