Wall Lettuce
Kingdom: Plantae, Division: Tracheophyta, Class: Magnoliopsida, Order: Asterales, Family: Asteraceae, Genus: Lactuca, Species: Lactuca muralis · Asteraceae (Sunflower or Daisy family) · Simple, deeply pinnately lobed (lyrate); note that this specimen primarily shows the flowering herbarium branch with minimal cauline leaves.
Species
Lactuca muralis (formerly Mycelis muralis)
Leaf Type
Simple, deeply pinnately lobed (lyrate); note that this specimen primarily shows the flowering herbarium branch with minimal cauline leaves.
Family
Asteraceae (Sunflower or Daisy family)
Shape
The basal leaves are lyrate-pinnatifid with a large terminal lobe; stem leaves are smaller, alternate, and clasping.
Size
Flowering stem shown is roughly 8-12 inches long; typical basal leaves range from 2-7 inches long.
Margin
Dentate to irregularly toothed on the lobes.
Arrangement
Alternate along the flowering stem; basal leaves form a rosette.
Rarity
Very Common; often considered a weed in its native and introduced ranges.
Color & Pattern
Stem is typically green to purplish; flowers are a distinct pale yellow. Leaves are dark green above and often have a purplish tint on the underside.
Venation Pattern
Pinnate venation with a prominent midrib.
Texture & Surface
Smooth (glabrous) and slightly thin or papery when dried.
Description
A slender, hairless biennial or perennial herb characterized by a thin, often purple-tinged stem that exudes a milky latex when broken. It produces delicate, open panicles of small yellow flower heads, each containing exactly five ray florets.
Key Features
The most diagnostic feature is the flower head containing only 5 yellow ray florets (looking like 5 petals) and the thin, wiry, dark flowering stalks.
Habitat
Typically found in shady woodlands, old walls, rocky outcrops, and disturbed urban areas with moist, calcareous soils.
Geographic Range
Native to Europe and Western Asia; widely naturalized in North America, particularly the Pacific Northwest and Northeast.
Condition Notes
Pressed herbarium specimen; flowers have retained some yellow pigment, though the stem has darkened significantly due to the drying process. Good condition for identification.
Interesting Facts
Unlike many members of the Asteraceae family that have dozens of florets per head, Wall Lettuce is unique for its consistent count of five ray florets.
Medicinal & Uses
No significant modern medicinal or commercial uses; historically used as a minor salad green in some cultures, though quite bitter.
Ecological Role
Provides nectar for small bees and hoverflies; seeds are dispersed by wind via a white pappus.
Similar Species
Lapsana communis (Nipplewort), which has more florets per head, and various Rattlesnake-roots (Prenanthes spp.).
Foraging Tips
Look for it in the late spring and summer in shady, damp crevices of stone walls or at the base of trees in deciduous forests.
Toxicity Warning
Non-toxic, though the milky sap (latex) can be a mild skin irritant for sensitive individuals. Generally considered safe but unpalatable due to bitterness.