Black cottonwood is the largest and tallest of the poplars, growing 2'-3' (or more) in diameter and well over 100' tall with a broad open crown.  The wood of the trunk is somewhat soft and whitish, aging to gray, and deeply furrowed in older individuals. The leaves are ovate, sometimes almost triangular, alternate, dark green above and lighter beneath, finely serrate with rounded teeth.  They are truncate to cordate at the base and acute to tapered at the apex, and are positioned on rounded petioles that are from 3/4" to 1-1/2" long.  The winter buds are long-pointed and are covered by a resinous substance, hence the name 'balsamifera.'   The flowers appear in apetalous catkins, staminate and pistillate on separate trees.  The third and fourth pictures show pistillate catkins.  The fruit is a nearly-sessile spheric to conic 2-4-valved capsule that upon opening releases minute seeds covered with cottony hairs designed for airborne dispersal.  Black cottonwoods are typically found along stream margins in sandy soils below 6000' in most of California and bloom from February to April.  They can be easily distinguished from our other common poplar, P. fremontii, which has leaves that are widely deltoid with roughly scalloped margins, bright green surfaces both above and below, and flattened petioles.

Click here for Latin name derivations: 1) Populus 2) balsamifera 3) trichocarpa.
Pronunciation: POP-yoo-lus ball-sam-IF-er-a tri-ko-KAR-pa.
Click here for Botanical Term Meanings.