showy blue lettuce

not listed

N4N5 - Apparently Secure to Secure

SNR - Unranked

not listed

UPL - Obligate upland

FAC - Facultative

FAC - Facultative

Showy blue lettuce is a 1′ to 4′ tall, erect, perennial forb rising on usually a single stem from deep-seated, creeping roots. The stems and leaves contain a milky latex.

The stems are leafy and hairless.

The leaves are bluish-green, alternate, and unlobed or with narrow lobes. The underside of the leaves are often covered with a white, waxy bloom.

The inflorescence is several heads in a branched cluster.

The flower heads are about ¾″ across and have 10 to 50, usually at least 15, ray florets.

The fruit is a reddish-brown achene with fluffy, white bristles attached to the tip.

1′ to 4′

Blue to purple

This plant is easily distinguished from other lettuce species by its large, showy flowers.

Canada lettuce (Lactuca canadensis) has yellow flowers.

Prairie lettuce (Lactuca ludoviciana) has prickles along the leaf margins and on the midvein on the underside of the leaf.

Prickly lettuce (Lactuca serriola) has yellow flowers. The leaves have prickles on the leaf margins and on the underside of the midvein.

The blue species of Lactuca are extremely variable and identifying characteristics overlap, factors which, taken together, make the species difficult to separate.

Tall blue lettuce (Lactuca biennis) has smaller flower heads that are about ⅜″ across. The achene has grayish-brown bristles attached to the tip.

Woodland lettuce (Lactuca floridana var. floridana) has smaller flower heads that are about ⅜″ across.

Moist. Meadows, thickets, prairies.

June to September

Sources

2, 3, 4, 5, 7, 28.

Native

Considerable disagreement exists about the proper scientific name for this plant. At least six names are currently (3/17/2021) in use by widely respected authorities.

ITIS³⁷ classifies it as Mulgedium oblongifolium;

GRIN as Lactuca tatarica ssp. pulchella;

The Plant List³⁶ and FNA⁴⁵ as Mulgedium pulchellum;

PLANTS³ as Lactuca tatarica var. pulchella;

The Global Compositae Checklist³⁹ classifies Lactuca tatarica ssp. pulchella as Lactuca tatarica, with no subspecies or varieties recognized, and Lactuca tatarica var. pulchella as Mulgedium pulchellum; and

Plants of the World Online as Lactuca pulchella.

Closer to home, both Minnesota DNR (MNTaxa) and Bell Herbarium⁴ classify it as Mulgedium pulchellum.

Chadde, in Flora of Minnesota, Second Edition (2019), classifies it as Lactuca pulchella.