Wild Lettuce Identification Guide For North America

One of the more common ‘types’ of plants to grace North America, but get almost no interest from gardeners is Wild Lettuce. You are likely to have encountered one of these plants whether hiking, finding it in your garden (unwanted sprouting) or even growing through a crack in the sidewalk!

There are over a dozen species of Wild Lettuce present in North America^[1][2]. Most are native, and some are invasive. But unfortunately they are all normally just referred to by their common name, Wild Lettuce. Well, in this guide I’ll speak to the ecological role these plants play within our environment and ecosystem, as well as help you to differentiate and identify the most common species (native and established) in North America.

As weedy as wild lettuce plants can be, they do serve a role in our ecosystem (at least the native ones) in that the flowers do feed pollinators. Additionally Finches have been known to eat the seeds, and deer/livestock have been known to forage on the leaves.

Identification characteristics that are common to all lettuces

Before jumping into specific lettuce identification I want to cover some common characteristics of wild lettuce. All mature lettuce leaves are alternate along the stalk, will have a prominent mid-rib running parallel to the leaf length, and the underside of the length and is hairy.

All Lettuces have flowers that somewhat resemble the common dandelion (they’re in the same family) both when bloom and as seed heads. In fact the seed heads have the little tufts of hair that can carry the seed far and wide.

These flowers are quite beautiful when examined in isolation. But rarely could this plant be considered showy. This is because the flowerheads are just too small to really standout relative to the rest of the plant.

Furthermore, if the leaves or stalk is cut, a milky-white sap will emerge. And many of the wild species have pinnatifid (irregularly lobed) leaves that will be quite unique.

And this sap that these Wild Lettuces emit? Well, they have been used as a painkiller as well as having other medical uses for centuries^[3]. It doesn’t take much research to find numerous recipes and methods for people who make their own natural medicines using the sap and other parts of Wild Lettuce. Now, I won’t be providing you any information on that topic as it isn’t my specialty. However, there is lots of info out there, but I can’t vouch for any of it.

Wild Lettuce Identification and Characteristics reference table

Species	Lifecycle	Stalk	Leaves	Flower
Lactuca biennis	Annual or biennial	Round green stems with a waxy or powdery coating that comes off when rubbed. Overall height can approach 3-6′.	Alternate lanceolate to ovate leaves that are pinnatifid, up to 15″ long by 7″ wide.	Panicles of flowerheads that consist of ray flowers (daisy-like), 1/4-3/8″ diameter. Color can be any shade from blue, to white, to yellow. Can be 10-50 ray flowers in a single flowerhead.
Lactuca canadensis	Biennial	3-8′ tall, round, light green stalk with red/purple streaks.	Alternate, up to 3″x10″, lanceolate-oblong. Large leaves have deep pinnate lobes. Sometimes margins are serrated, short fine hairs underside central vein.	Panicles up to 2′ long of flowerheads that are similar to dandelions. Flowerheads are 1/4-5/16″ diameter, yellow to reddish-orange. The achenes (seeds) are dark brown.
Lactuca floridana	Annual or biennial	Smooth round stems that are purple to green in color.	Opposite leaves, oblong to elliptic, the margins are smooth to dente.	Pyramidal panicles, individual florets are 3/8″-1/2″ diameter. Petals are blue to white.
Lactuca graminifolia	Biennial	Hairy to glabrous, round, 1-5′ tall, green to purple-green.	Alternate, lance-linear shape, most often entire margins or dente. Can be pinnately lobed	Peduncles of 6-50 florets, yellow-blue, pink, or white in color. 1/4″diameter
Lactuca hirsuta	Biennial	3-7′ tall, round stem light green to purple in color. The stalk is hairy near the bottom, becoming more smooth as it ascends.	Alternate leaves that are pinnatifid and irregularly lobed with an overall ovate shape. Margins are ciliate to denticulate.	12″ panicles of flowerheads occur at the top. Individual flowerheads are 1/4-3/8″ diameter with 10-30 ray flowers tha t are lighter shade of red-purple to pink. There will be purple bracts at the base of the flowerhead.
Lactucaludoviciana	Biennial	2-5′ tall, round, light green stalk	Basal leaves the first year, 6″ long x 2″ wide, elliptic-lanceolate or obovate. In 2nd year, alternate leaves 2″ wide by 8″ long, elliptic-lanceolate, margins can be pinnatifid or un-lobed, with dentate margins	Panicles of flowerheads that are roughly 1’x1′. Individual flowerheads don’t always open, but are 1/4″-3/4″ diameter. There are 20-60 ray florets (petals). Color can range from light blue to yellow-white.
Lactuca pulchella[4]	Annual or biennial	1-3′ tall, round green stalk, smooth	Alternate linear-lanceolate leaves, 1-3″ long.	Panicles of blue, 1″ diameter flowerheads. 10-30 ray florets.
Lactuca saligna	Annual	1′ tall, round, light-green to light purple stalk.	Alternate linear leaves, 1-4″ long, entire to prickly/denticulate margins	Panicles of 1/2″ diameter yellow flowers with 8-20 ray florets
Lactuca sativa	Annual or biennial	6″-24″ tall, round green stalk, smooth	Alternate, ovate shaped leave 4-7″ long, pinnately divided	Panicles of blue to yellow flowers, 1″ diameter
Lactuca serriola	Annual / Biennial	2-7′ tall, round, green to white. Sometimes with thorns near base.	Alternate leaves, up to 4″ wide by 12″ long, with larger size at base. Pinnately lobed with prickly (spinulose) margins and on central vein on underside.	Panicles of flowerheads with pale-yellow flowers near the top of central stem and branches. Flowers are 5/16″ diameter with ~ 20 petals that are toothed @ end
Lactuca tatarica (synonym Mulgedium pulchellum)[5]	Perennial	1-2′ tall, glabrous, round green stalk	Alternate gray-green leaves ellpitic, up to 7″ long by 2″ wide, pinnatifid lobed. Margins are spinulose to smooth, or denticulate	Inflorescence is from racemes to panicles of blue 1″ diameter flowerheads. 10-20 blue ray florets per ead.

Species of Wild Lettuce commonly found in North America

Below I’ll have images showing the various species of Wild Lettuce as well as maps depicting their native range to the state/province level. Click on the images to enlarge.

Tall Blue Lettuce – Latuca biennis

Often found in disturbed areas, this native is annual or biennial. It can grow quite tall, commonly upwards of 6′! The roots were used by Native Americans to treat a variety of gastronomical ailments.

Wild Lettuce – Latuca canadensis

Easily confused with the highly invasive species, Lactuca serriola, you can differentiate this species in that it is smooth except for the sparse hairs under the midrib, and that L. serriola has more ‘blueish’ colored leaves. But you can find this species in part shade to part sun inhabiting woodland edges and roadsides.

Of all the wild lettuces, the hairs on the leaf mid-rib for this specific species are a bit inconsistent. Make sure you check multiple leaves before making your ID.

Florida Blue Lettuce / Woodland Lettuce – Latuca floridana

A very tall plant reaching upwards of 7′ in optimum conditions, Florida Blue Lettuce can be an annual or biennial in moist areas. The individual blue-white flowers are quite pretty when examined up close, although the overall plant wouldn’t be considered showy as the flowers relative to the plant size are quite small.

While the young leaves can be eaten raw, once they get older they develop a bitter taste.

Grassleaf Lettuce – Latuca graminifolia

A shorter type of wild lettuce, Grassleaf Lettuce typically grows 1-2′ tall in full sun and well drained soil. It’s leaves are smaller and linear, and the flowers are highly variable in color from pink to yellow or even white.

Tall Hairy Lettuce – Latuca hirsuta

A biennial, Tall Hairy Lettuce spends it’s first year as a clump of basal leaves while developing it’s taproot. Commonly found throughout Eastern North America, it prefers drier soils and grows in clearings, roadsides, and along the forest edge.

One key identification trait of this species is that the panicles of flowerheads are more open than other species, and the secondary branches can be nearly as long as the primary. This gives it a larger, more spreading appearance, but probably takes away from the showiness of the overall plant as the flowers aren’t as packed together.

Prairie Lettuce – Latuca ludoviciana

As a biennial Prairie Lettuce spends it’s first year as a rosette of basal leaves that are roughly 2″x6″ long. But in it’s second year it can reach 4-5′ tall in dry to medium moist soil and full sun. The key to identifying this species from other is that it will produce a brown sap rather than the typical white sap of other species.

Common Blue Lettuce – Latuca pulchella

Common throughout North America with the exception of the South East, Common Blue Lettuce grows upwards of 2′ tall and is a prolific self-seeder. It can often be confused with L. biennis, but can be differentiated as the latter has brown seeds.

Willowleaf Lettuce – Latuca saligna

This wild lettuce is quite weedy and invasive in North America. Although commonly encountered from the Mid-Atlantic to Eastern Kansas, Willowleaf Lettuce is native to Europe and Western Asia. Typically it grows 6″-36″ tall in full sun.

Lettuce – Latuca sativa

Yes, this species, Latuca sativa is commonly known as lettuce. It has many varieties such as Ice Berg….but yes, this is the common lettuce you can purchase in grocery stores the world over. Like all lettuces, if you let it grow long enough, it will bolt and produce seed. And thus it has become an established invasive in several states from California to Maine.

If you see this lettuce when young, you may see the customary ‘head’ of lettuce. After bolting, it will grow 2′ tall with panicles of 1″ blue to yellow flowerheads.

Prickly Lettuce – Latuca serriola

If you’ve found your way to this guide, it is probably because of this annoying weed. Prickly Lettuce is well established throughout North America. It tends to stand out in that it has very prominent prickles on the leaves (making it painful to pull bare-handed), and the leaves have a blueish-green color.

If you have this plant in a flower bed – pull it. Put on some canvas gloves and rip it out while young before the taproot can develop. The thing is, they are pretty successful self-seeders and you will be guaranteed find more the coming seasons.

Blue Lettuce – Latuca tatarica

Found along roadsides, waterways, meadows, and often growing in poor-draining soil, Blue Lettuce can reach 2′ tall in full sun. A perennial, it spreads via self-seeding and is used as forage by many mammals.

Find more native plants here