white poplar

not listed

NNA - Not applicable

SNA - Not applicable

not listed

Considered a weed in Wisconsin and Tennessee. Not listed in Minnesota.

White poplar is a fast-growing, short-lived, deciduous tree rising on a single trunk from a shallow, spreading root system. In Minnesota, mature trees are usually 40′ to 70′ tall and up to 24″ in diameter at breast height, though large individuals can reach 89′ in height and 78 ″ in diameter. It often has shoots (suckers) rising from the roots up to 100′ from the trunk, and sometimes forms extensive colonies. For this reason, it is sometimes considered a weed.

The trunk is short, much branched, often crooked, and often forked near the base. When growing in a forest, the crown is thin and narrow. When in an open area, it is broad and rounded. The branches are stout, crooked, and spreading to ascending.

The bark on young trees is smooth and greenish-white. After several years it is gray to grayish-brown with dark, conspicuous pores (lenticels). The lenticels are large, raised, corky, and distinctly diamond-shaped. On older trees the bark near the base is thick, dark gray, and rough, with longitudinal furrows and ridges.

Young twigs are slender, greenish-gray, and densely covered with whitish-gray, felt-like hairs. They are round in cross section and have white pith. As they age they become hairless or nearly hairless.

Terminal buds are ⅛″ to ⅜″ long, egg-shaped, and pointed. They are not resinous. They are densely covered with whitish-gray, felt-like hairs. Lateral buds are similar but smaller.

Two types of leaves are produced: early (preformed) leaves; and late (neoformed) leaves. Preformed leaves overwinter in the bud and are fully formed or almost fully formed before the buds burst in the spring. They are the first leaves to mature in the spring. Neoformed leaves are all of the subsequent leaves produced on long shoots. They are formed in the same season that they emerge.

All leaves are deciduous and alternate. The leaf stalks (petioles) are 1″ to 23 ⁄16″ long, shorter than the leaf blades, and are more or less round in cross section, not flattened. They are densely covered with white, woolly hairs. There are no conspicuous glands on the petiole. There is sometimes a pair of cup-shaped glands at or near the base of the leaf blade.

Preformed leaf blades are egg-shaped, unlobed, 1½″ to 2⅜″ long, and slightly less wide. They taper or are angled to a blunt point at the tip, and are rounded or slightly heart-shaped at the base. The upper surface is dark green and shiny, densely hairy at first, becoming thinly hairy just along the main veins when mature. The lower surface is densely covered with persistent, white, felt-like hairs. The margins are minutely hairy and have 3 to 8 broad, coarse teeth or scallops per side as well as scattered small teeth. There is no thin yellow or translucent line or band along the margin. Neoformed leaves are larger, 2⅜″ to 4¾″ long, and are palmately lobed with 3 or 5 lobes. Their shape is similar to a maple leaf. The margins are irregularly finely toothed and scalloped. They are otherwise similar to preformed leaves. The leaves turn reddish-yellow In autumn.

Male (staminate) and female (pistillate) flowers are borne on separate trees. They appear before the leaves in March to May. Both male and female flowers are borne in narrow, crowded, short-stalked or almost stalkless clusters (catkins). The catkins emerge from lateral buds on 2nd year twigs. Staminate catkins are 13 ⁄16″ to 2⅜″ long and pendulous, pistillate catkins 2″ to 4″ long, arched, and drooping.

Each staminate flower consists of a cup-like disk and 6 to 12 stamens, and is subtended by a single, nearly oval, modified leaf (bract). The stamens have anthers that turn bright red before shedding pollen. The bract is toothed, not lobed, and has long, silky hairs along the margins, at least toward the tip. Each pistillate flower consists of a disk, a naked superior ovary, and a single style, and is subtended by a single bract. The style is branched nearly to the base and has a slender stigma at each tip

The fruit is a narrowly egg-shaped, hairless, ⅛″ to 3 ⁄16″ long, 2-valved capsule. They are green at first, turning brown at maturity. The seeds are about 1 ⁄16″ long and are surrounded by long silky hairs that are attached at the base of the seed. They are released in late spring to early summer and are dispersed by wind.

40′ to 70′

No records kept for non-native trees.

Gray to reddish

Moist. Upland forests, stream banks, roadsides, field borders, and old homesites. Full or partial sun; shade intolerant. Well drained soil.

March to May

Sources

2, 3, 4, 7, 8, 22, 24, 28, 29, 30.

Native to Europe, Asia, North Africa, and the Canary Islands. Introduced into North America in 1748. Widely cultivated. Sometimes escapes cultivation. Widely naturalized in the United States and southern Canada.

Uncommon in Minnesota

Form of mature white poplar, South Central Minnesota, December 2017

White poplar, near MN/IA border, 2016

Tree

Branch

Leaves

Leaf Underside

New Growth

Location: South Central Minnesota

Form of mature white poplar

Location: near MN/IA border