Appendices & Glossary - Botanical Research Institute of Texas

1324 APPENDIX TWENTY-ONE/COMMERCIALLY IMPORTANT TIMBER TREES OF EAST TEXAS
PLATANUS OCCIDENTALIS L. AMERICAN SYCAMORE
(PLATANACEAE, PLANE-TREE FAMILY)
Other Common Names: EASTERN SYCAMORE, BUTTONWOOD, PLANE TREE, AMERICAN PLANE TREE, BUTTONBALL TREE, WATER
BEECH
Form and Size: large tree to 50+ m; trunk straight, tall or soon branching, becoming massive, to 3.5(–4+) m in diameter
(one of the largest trees in the eastern deciduous forest); crown spreading at the top, broad, open, irregular.
Leaves: deciduous, simple, alternate, long-petioled, the petiole hollow at base and completely surrounding the axillary
bud; leaf blades large, to ca. 20 cm long and 25 cm wide (larger on sucker shoots), broadest near the base and marginally
with 3–5(–7) broad, shallow lobes along the margin, the lobes acute or acuminate, entire or coarsely toothed, the sinuses
between lobes rounded, the blade surfaces at first coated with soft, whitish stellate (= star-shaped) hairs, becoming
sparsely pubescent with age; stipules sometimes persisting, conspicuous, entire or toothed.
Buds: terminal bud usually absent, lateral buds 6–10 mm long, cone-shaped, smooth, shiny, covered by 3 brown scales,
hidden in the petiole bases.
Flowers: unisexual, male and female flowers occurring on the same tree (plants monoecious), numerous, individually
tiny, in stalked, globular, dense clusters/heads; sepals and petals minute; male flower clusters 7–10 mm in diameter,
reddish to yellow, on branchlets of the previous year; female flower clusters 10–14 mm in diameter, greenish-red, on
older branchlets.
Fruits: in conspicuously pendulous (on stalks 8–16 cm long), usually solitary(–rarely 2 together), brownish, ball-like heads
ca. 2–4 cm in diameter, the heads consisting of numerous closely packed, long, narrow fruits, the individual fruits 7–10
mm long, indehiscent, single-seeded, surrounded at base by a tuft of tawny hairs (which aid in wind dispersal).
Bark: on young trees produced in small, thick scales, dark reddish-brown; on the upper part of the trunk and on older
trees, the bark separates into large, thin, scales that resemble pieces of a jigsaw puzzle or mosaic and fall away to expose
the smooth, strikingly lighter-colored, white to tan or greenish inner bark.
Wood: sapwood whitish to yellowish or reddish brown; heartwood light to dark brown or reddish brown when distinguishable;
grain generally irregularly interlocked; growth rings distinct.
Habitat: stream banks, river and stream bottoms, floodplains, and moist ravines, typically on alluvial soils; though generally
in areas with significant moisture and tolerant of poorly drained soils, this species cannot stand extended flooding during
the growing season.
Range: Pineywoods and northern Gulf Prairies and Marshes west to East Cross Timbers and Edwards Plateau; widespread
in the eastern U.S. west to NE and TX; also mountains of northeastern Mexico.
Principal Uses: chopping blocks, boxes, crates, pallets; also furniture, but tends to warp easily when sawn into lumber and
is difficult to work; gives beautiful figure when quartersawn, but it has not been sufficiently recognized or widely used,
probably because it is difficult to work with; also veneer and pulpwood.
Historical Uses: one of earliest uses was by farmers who would cut hollow trunks, saw them in lengths of three or four
feet, and nail bottoms to one end for use as grain barrels, called gums or hogsheads. The resistance to splitting made it
valuable for chopping blocks and buttons (hence the common name BUTTONWOOD). The wood was also used for slack
cooperage (= barrels for storing dry goods; especially for sugar and flour barrels because it does not impart taste, odor,
or stain), ox yokes, ox cart wheels, plug tobacco boxes, musical instruments, and saddle trees.
Other Significant Information: this is one of tallest angiosperms in North America, reaching 50+ m, and it has the greatest
trunk diameter, attaining 4+ m. The species is being grown in the southeastern U.S. for fiber in intensively cultured
“biomass farms.” The ball-like fruit clusters break apart slowly, with some persisting on the leafless branchlets
throughout the winter. The fruits were a favorite food of the now extinct Carolina parakeet. “In North America
Platanus is usually called sycamore, a name apparently borrowed from the European sycamore maple, Acer
pseudoplatanus Linneaus, which has similar leaves. That name in turn comes from the Middle Eastern sycomore fig,
Ficus sycomorus Linnaeus, its specific epithet from the Greek sykomoros, mulberry” (Kaul 1997).
Recognition in the Field: smooth, strikingly white, tan, and green, mottled bark (and thus easily recognized at a distance);
large 3–5(–7)-lobed leaves with petiole bases surrounding and completely hiding axillary buds; fruits in dangling, pingpong
ball size clusters.