Lactuca laciniatus, wall lettuce
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Herbaceous

Lactuca laciniatus

wall lettuce

AsteraceaeEurope, western Asia

At a Glance

TypeAnnual
HabitUpright
FoliageDeciduous
Height12-36 inches (30-90 cm)
Width6-12 inches (15-30 cm)

Overview

Mycelis muralis (syn. Lactuca muralis) is a slender, glabrous annual or short-lived perennial in the daisy family (Asteraceae) reaching 12–36 inches (30–90 cm) tall with a 6–12 inch (15–30 cm) spread. Stems are erect, slender, wiry, freely branching in the upper half, smooth, and exuding milky latex when broken. Basal and lower stem leaves are lyrate-pinnatifid, 2–6 inches (5–15 cm) long, with a large, triangular terminal lobe and 2–4 pairs of smaller, angular lateral lobes; thin-textured, dark green, often with a purplish tinge. Upper stem leaves are smaller, often unlobed, clasping. Flower heads are small, 0.3–0.4 inch (7–10 mm) across, with exactly 5 yellow ligulate florets — a distinctive and diagnostic count. Heads are borne in loose, open panicles. Fruit is a dark achene with a white pappus for wind dispersal. A single plant produces 500–3,000 seeds. Colonizes shaded walls, rocky outcrops, woodland edges, and shaded urban sites. Less competitive than other Asteraceae weeds in open, sunny habitats.

Native Range

Native to Europe and western Asia, occurring on shaded walls, rocky banks, woodland edges, and disturbed shaded ground from sea level to approximately 6,000 feet (1,800 m). Naturalized in the Pacific Northwest, northeastern United States, and British Columbia, primarily in shaded urban and peri-urban settings.

Suggested Uses

Used in Asteraceae identification courses for teaching the diagnostic 5-floret head count. Included in shade-tolerant weed identification. The lyrate leaf shape is used in leaf morphology exercises. Studied in urban ecology as a colonizer of walls and shaded hardscape.

How to Identify

Identified by the exactly 5 yellow ligulate florets per head — unique among common Asteraceae weeds. Distinguished from Lactuca serriola (prickly lettuce) by the much smaller overall size, the 5-flowered heads (versus 12–20 florets), and the absence of prickles on the leaf midrib. Distinguished from Lapsana communis (nipplewort) by the milky latex (absent in Lapsana), the lyrate leaf shape, and the pappus (absent in Lapsana). The thin, often purplish leaves with a large triangular terminal lobe are characteristic.

Appearance

Size & Dimensions

Height1' - 3'
Width/Spread6" - 1'

Colors

Flower Colors

yellow

Foliage Colors

green
purple

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~6 weeks
J
F
M
A
M
J
J
A
S
O
N
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Summer
Flowers from June through August. Individual heads open for 1 day. The loose panicle produces heads over 4–6 weeks. Self-pollinating. Seeds mature 2 weeks after flowering and disperse by wind via the pappus. In the Pacific Northwest, peak flowering occurs in July.

Detailed Descriptions

Flower Description

Yellow

Foliage Description

Dark green to purplish, lyrate-pinnatifid with a large triangular terminal lobe and smaller lateral lobes; thin, glabrous

Growing Conditions

Sun Requirements

Partial Shade
Full Shade
Requires 2-6 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 8.0(Neutral)
357912
Soil Types
loamsiltrocky
Drainage
well drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Care & Maintenance

Care Guide

Hand-pulling before seed set is straightforward; the slender taproot extracts easily from crevices and moist soil. The annual or short-lived habit means consistent removal before seed set for 1–2 years substantially reduces populations. Less aggressive than many Asteraceae weeds; rarely forms dense stands. Shade tolerance allows colonization of walls, rockeries, and shaded bed edges where other weeds are less competitive.

Pruning

No pruning applicable. Plants are removed by pulling before seed maturity. The slender habit and shallow roots make removal easy. In wall crevices, removal of the root from between stones may require a narrow tool.

Maintenance Level

low

⚠️ Toxicity Warning

Non-toxic