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Native Plant Trust: Go Botany Discover thousands of New England plants

Lactuca canadensis — tall lettuce

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Facts

The leaves of tall lettuce are high in several vitamins and can be eaten raw when young or boiled later in the season. Native Americans used an infusion to treat pain, as a stimulant, and for calming the nerves. The milky sap was used topically to treat warts and poison ivy.

Habitat

Anthropogenic (man-made or disturbed habitats), forest edges, meadows and fields

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf type
leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
Leaf arrangement
alternate: there is one leaf per node along the stem
Leaf blade edges
  • the edge of the leaf blade has lobes, or it has both teeth and lobes
  • the edge of the leaf blade has no teeth or lobes
  • the edge of the leaf blade has teeth
Flower type in flower heads
the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray
Ray flower color
  • blue to purple
  • yellow
Tuft or plume on fruit
at least a part of the plume is made up of fine bristles
Spines on plant
the plant has no spines
Leaf blade length
100–350 mm
Disk flower number
0
Show all characteristics

  • Flowers

    Bases of bract appendages
    NA
    Disk flower color
    NA
    Disk flower lobe number
    0
    Disk flower number
    0
    Disk flower proportions
    NA
    Disk flower reproductive parts
    NA
    Disk flower shape
    NA
    Flower head outer flowers
    at the outer edge of the flower head, each flower has a single enlarged lobe or strap
    Flower head platform
    the base has no bristles or papery scales
    Flower head platform surface
    NA
    Flower head shape
    the sides of the flower head are roughly parallel, like a cylinder
    Flower type in flower heads
    the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray
    Height of flower head base
    10–15 mm
    Inflorescence branching (Solidago)
    NA
    Inflorescence shape
    • the inflorescence is flat-topped in profile
    • the inflorescence is not flat-topped but appears rounded, with some flower heads distinctly higher than others
    Ovary beak
    there is a beak on the ovary
    Ovary cross-section
    the ovary is compressed (flattened)
    Ovary hair type
    the ovary has no hairs on it
    Ovary hairs
    the ovary has no hairs on it
    Ovary profile
    • in profile, the ovary is roughly egg-shaped, but widest above the middle
    • in profile, the ovary is roughly elliptical (widest in the middle, tapering to both ends)
    Ovary surface
    the ovary surface is textured with tiny points, bumps or wrinkles
    Ray flower color
    • blue to purple
    • yellow
    Ray flower reproductive parts
    the ray flowers have both carpels and stamens
    Ray flowers
    • 11-15
    • 16-25
    Reproductive system
    all the flowers on the plant contain both carpels and stamens
    Rim at top of ovary
    the central flowers have a disk-shaped platform above the ovary
    Scale tip
    NA
    Smaller bracts at base of bracts
    there is a cycle of much smaller bracts outside the cycle of larger and longer bracts
    Style branch number
    there are no obvious branches on the style
    Width of flower head base
    4–6 mm

  • Fruits or seeds

    Ovary beak length
    1–3 mm
    Ovary width in developed fruit
    1.5–1.8 mm
    Seed hair tuft color
    the pappus hairs are white or off-white
    Seed hair tuft length
    5–7 mm
    Seed hair tuft tips
    the pappus hairs are slender
    Seed tuft scale number
    0
    Seed tuft type
    the pappus is made of very fine hairs or bristles
    Top of disk flower ovary
    NA
    Tuft or plume on fruit
    at least a part of the plume is made up of fine bristles

  • Glands or sap

    Leaf blade glands
    the leaf blades have no glandular (translucent) dots or scales
    Sap
    the sap is milky and opaque, and may be white or colored

  • Growth form

    Growth form
    the plant has one or more free-standing stems
    Plant lifespan
    • the plant is annual, it lacks evidence of previous years' growth
    • the plant is biennial, it appears as either first year (non-reproductive) plants or second year plants with flowers or fruit
    Spines on plant
    the plant has no spines
    Underground organs
    there is a thickened taproot on the plant

  • Leaves

    Hairs on underside of leaf blade
    • the underside of the leaf is fuzzy or hairy
    • the underside of the leaf is not hairy, or has very few hairs
    Leaf arrangement
    alternate: there is one leaf per node along the stem
    Leaf blade base
    • the leaf has no petiole
    • the leaf has no petiole and at the base it clasps the stem, or goes all the way around the stem so the stem appears to pierce the leaf
    Leaf blade base shape
    the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow
    Leaf blade bloom
    there is a noticeable powdery or waxy bloom on the underside of the leaf
    Leaf blade edges
    • the edge of the leaf blade has lobes, or it has both teeth and lobes
    • the edge of the leaf blade has no teeth or lobes
    • the edge of the leaf blade has teeth
    Leaf blade length
    100–350 mm
    Leaf blade shape
    • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
    • the leaf blade is linear (very narrow with more or less parallel sides)
    • the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is oblong (rectangular but with rounded ends)
    • the leaf blade is obovate (egg-shaped, but with the widest point above the middle of the leaf blade)
    • the leaf blade is spatulate (spoon-shaped; narrow near the base, then suddenly widening to a rounded tip)
    Leaf blade surface colors
    there is no noticeable color variation on the upper surface of the leaf
    Leaf blade tip
    • the tip of the leaf blade is acuminate (tapers to a long, thin point)
    • the tip of the leaf blade is acute (sharply pointed)
    Leaf blade width
    15–120 mm
    Leaf disposition
    the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
    Leaf spines
    there are no spines on the leaf edges
    Leaf stalk
    the leaves have no leaf stalks, but attach directly to the stem
    Leaf tip extension
    NA
    Leaf type
    leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
    Leaflet number
    0
    Specific leaf type
    • the leaf has a row of two or more lobes on each side of the central axis
    • the leaves are simple (i.e., lobed or unlobed but not separated into leaflets

  • Place

    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of forests
    • man-made or disturbed habitats
    • meadows or fields

  • Scent

    Plant odor
    the plant does not have much of an odor

  • Stem, shoot, branch

    Flowering stem cross-section
    the flowering stem is circular, or with lots of small angles
    Leaves on stem
    there is at least one full leaf above the base of the flowering stem
    Stem bloom
    • the stem has a powdery or waxy film on it that can be rubbed away
    • there is no powdery or waxy film on the stem
    Stem internode hair direction
    the hairs point mostly upwards to outwards
    Stem internode hair length
    At least 0 mm
    Stem internode hairs
    • the stem has hairs between the nodes
    • the stem has no hairs between the nodes
    Stem wings
    the stem does not have wings on it

Wetland status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

In New England

Distribution

Connecticut
present
Maine
present
Massachusetts
present
New Hampshire
present
Rhode Island
present
Vermont
present

Conservation status

Exact status definitions can vary from state to state. For details, please check with your state.

Massachusetts
widespread (S-rank: S5)

From Flora Novae Angliae dichotomous key

2.  Lactuca canadensis L. N

tall lettuce. Lactuca canadensis L. var. integrifolia (Bigelow) Torr. & Gray; L. canadensis L. var. latifolia Kuntze; L. canadensis L. var. longifolia (Michx.) Farw.; L. canadensis L. var. obovata Wieg.; L. sagittifolia Ell. • CT, MA, ME, NH, RI, VT. Fields, roadsides, forest edges and clearings.

1×2. Lactuca biennis × Lactuca canadensis → Lactuca ×‌morssii B. L. Robins. is a rare lettuce hybrid known from MA, ME. It is intermediate between the parental taxa or sometimes combines characteristics. It usually has blue ray flowers and off-white pappus bristles, the cypsela bodies intermediate or as in each parent (see key for differences in beak length and nerving of faces).

Native to North America?

Yes and no (some introduced)

Sometimes confused with

Lactuca biennis:
flowers usually blue and mature ovary beakless or with a short, stout beak 0.1-0.5 mm long (vs. L. canadensis, with flowers usually yellow and mature ovary with a slender, elongate beak 1-6 mm long).
Lactuca hirsuta:
involucre 15–22 mm tall in fruit, cypsela body 7–10 mm long including the beak, and pappus 8–12 mm long (vs. L. Canadensis, with the involucre 10–15 mm tall in fruit, cypsela body 4.5–6 mm long including the beak, and pappus 5–7 mm long).

Synonyms

  • Lactuca canadensis var. integrifolia (Bigelow) Torr. & Gray
  • Lactuca canadensis var. latifolia Kuntze
  • Lactuca canadensis var. longifolia (Michx.) Farw.
  • Lactuca canadensis var. obovata Wieg.
  • Lactuca sagittifolia Ell.

Family

Asteraceae

Genus

Lactuca