Flower:

Open branching cluster of stalked flowers at the tip of the plant and arising from leaf axils in the upper plant. The tiny dandelion-like flowers are ¼ to 1/3 inch across with 15 to 20+ rays (petals) with a few teeth at the tip of a ray. Color is typically yellow but may be tinged red or orange. The bracts (phyllaries) surrounding the base of a flower are variable in size, green often with purple tips, hairless, overlapping, appressed, and the entire structure (involucre) forming a tube about ½ inch (10 to 12 mm) long. Flower stalks are green and hairless.

Leaves:

Leaves are alternate, quite variable, those towards the base of the plant deeply lobed, 4 to 14 inches (10 to 35 cm) long and to ~5 inches wide, gradually becoming smaller as they ascend the stem. The lobes may be broad or narrow; the uppermost leaves may be broad or narrow as well and are mostly unlobed. Surfaces are usually hairless except for sparse hairs along the midvein on the underside. Leaf edges are often wavy and vary from toothless or nearly so to minutely or coarsely toothed.

Leaves are mostly stalkless and are often clasping with a pair of small lobes (auricles) at the base. Stems are single, erect, mostly smooth, green to purplish or spotted purple, sometimes with a waxy bloom, and unbranched except in the flower clusters. Leaves, stems and roots exude a pale orange-brown sap when broken.

Fruit:

Flower heads form seed heads about 1-inch in diameter with the phyllaries spreading out as seed matures. Seed is brown, often mottled, flattened, oval-elliptic, with a stiff, slender beak half to about as long as the seed body. At the tip of the beak is a tuft of white hairs to carry it off in the wind.

Notes:

Canada Wild Lettuce grows in a variety of conditions, from shady, moist woods to dry, gravelly roadsides, and is a highly variable species, particularly in leaf shape. Of the Minnesota Lactuca species, only it and Louisiana Lettuce (Lactuca ludoviciana) have pale orange-brown sap and flattened oval-elliptic seeds with a thread-like beak not longer than the seed body, where the others have milky white sap and different seeds. Louisiana Lettuce also is typically a shorter plant, has blue to purplish flowers, leaves are typically less deeply lobed, and is primarily (but not always) found in prairie habitats.

Of the other MN Lactuca species, besides the milky white sap, Tall Blue Lettuce (Lactuca biennis), may grow side-by-side with L. canadensis but has pale blue to whitish flowers, seeds with a very short (or absent) stout beak and light brown to grayish hairs, leaves usually have soft hairs on most veins, not just the midrib. Prickly Lettuce (Lactuca serriola), a non-native weed common in disturbed areas and may grow as tall as Canada Wild Lettuce, but has somewhat larger yellow flowers, the leaves have prickly hairs along the edges and midvein, seeds are paler brown to grayish, tapering at the base, and have a beak 1 to 2+ times as long as the seed body. Woodland Lettuce (Lactuca floridana), an uncommon species in Minnesota, has blue flowers, seeds much like L. biennis but with white hairs, and leaves often have a large triangular lobe at the tip and long narrow wings at the base.