Populus deltoides ssp. molinifera

Native

Common

Floodplains, along streams and lake shores. Full sun.

March to May

Reddish or greenish-yellow

60′ to 80′

This deciduous hardwood tree is the most massive tree in Minnesota. Mature trees in the state are usually 60′ to 80′ tall and up to 36″ in diameter at breast height. Large individuals can reach over 130′ in height. It is fast growing, in fact the fastest growing tree in North America, growing 6′ to 12′ per year under favorable conditions. It is short lived, commonly lasting only 50 years. In favorable conditions it may last 80 to 90 years. Older individuals can survive up to 200 years. It rises on a single stem from a shallow, wide-spreading root system. It rarely produces suckers.

In the open the trunk is short and massive. It often splits near the ground into a two or more widely-spreading stems, creating an open, broad, irregular crown. In a forest the trunk is long and straight and the crown is small and rounded.

The bark on young trees is smooth and yellowish-gray. As it ages it becomes thick, ashy gray to brown, and deeply furrowed, with whitish troughs and long, angular ridges.

The twigs are stout, smooth, hairless and light yellow or yellowish-brown with pale dots (lenticels). They are angular in cross section with narrow ridges extending down from each side of the bud.

Terminal buds are yellowish-brown, hairless, and sticky (resinous). They are ⅜″ to ¾″ long, slender, and 3-sided. They are widest at the middle, tapering slightly to the base and tapering to a long point at the tip. They are not aromatic. Lateral buds are similar but smaller, and diverge from the twig. The leaf scars are large, triangular, and 3-lobed, with 3 large bundle scars and eyelash-like hairs where the bud meets the scar.

The leaves are deciduous, alternate, thick, firm, and not lobed or divided (simple). They are triangle-shaped, 2″ to 4″ long and 2¼″ to 4⅓″ wide. They hang downward on yellowish, flattened, 1½″ to 3⅛″ long leaf stalks. The blades taper at the tip to a long point with concave sides along the tip. They are straight across (truncate) or almost straight across at the base. The upper surface is bright green, shiny or waxy, and hairless. The lower surface is similar but slightly paler green. The margins are coarsely toothed with 5 to 15 teeth per side. The teeth are rounded, forward pointing, and distinctly curved. There are no teeth along the tip or near the leaf stalk. There are usually 1 or 2 warty glands where the leaf blade attaches to the stalk. In autumn the leaves turn yellow to yellowish-orange. Leaves on suckers are similar but often larger.

Male and female flowers are borne on separate plants. They appear before the leaves in early April to early May. Both male and female flowers are borne in crowded, pendulous, short-stalked or almost stalkless catkins on 2^nd year branchlets. Male catkins are 2″ to 4¾″ long, stout, reddish, and densely flowered. Female catkins are 2⅜″ to 4¾″ long, slender, greenish-yellow, and few-flowered. Female catkins elongate when fruiting, becoming 3½″ to 6¾″ long.

The fruit is an egg-shaped, ¼″ to 7 ⁄16″ long, 3- or 4-valved capsule. Each capsule contains numerous seeds. The seeds are released late mid-May to early mid-June. They have cottony hairs attached and are dispersed by wind.

Eastern cottonwood (Populus deltoides ssp. deltoides) leaves have 20 to 25 teeth per side and 3 to 5 basal glands. It does not occur in Minnesota.

The champion plains cottonwood in Minnesota is on state property in Watson, in Chippewa County. In 2001 it was measured at 106′ tall and 394″ in circumference (125½″ in diameter).