Facts about Wall Lettuce

Lactuca muralis, or Mycelis muralis (L.) Dumort commonly known as wall Lettuce is a perennial flowering plant of the genus Lactuca in the family Asteraceae, subfamily Cichorioideae, tribe Cichorieae. Members of this tribe have flowers composed of either ray florets or disk florets, but never both. Wall Lettuce has always been easy to identify because it has only 5 petals on its ray flower, unlike any similar species. The plant is native to southern Europe and western Asia; it is invasive in Alaska and the Pacific Northwest. It has been found from eastern Canada south to New York and west to Minnesota. In New England, it is currently mapped in Maine, Massachusetts, New Hampshire, and Vermont. It can be found in woodlands, especially Beech. It is also found in cancerous soils, and walls. Apart from wall lettuce it is also known as ivy-leaved lettuce. The specific Latin epithet muralist is understood as growing on walls.

Wall Lettuce Facts

Plant Description

Wall Lettuce is a slender, hairless, biennial or perennial, herbaceous, flowering plant that normally grows about 25 to 150 cm (10 to 59 in) tall. The plant is found growing in shady spruce woods and rich mixed swamps, broad-leaved forests on the lower parts of mountains and rocky places, stream valleys, springs, clear-fell areas, beside walls and ruins, parks, gardens, pavements, roadsides, fields, waste lots, walls, rocks, sometimes in beech woods. Stems are erect, 2-3 ft. (0.6-0.9 m) tall, branched above and may one or more stems from a fibrous root. The stem surface is glabrous, often glucose, and exudes milky juice when broken.

Leaves

The lower leaves are lyre-shaped, pinnate shaped about 2.5-7 in. (6.4-17.8 cm) long, 1-3 in. (2.5-7.6 cm) wide, glabrous and deeply lobed, with broad, terminal segments. The lobes are triangular in shape, the terminal lobe being the largest. The upper leaves are stalked less, smaller, less lobed and they clasp the stems with rounded toothed lobes. All leaves are red-tinged.

Flower

The flower heads are yellow, small, 1 cm (1⁄2 in) wide more or less, on branches 90 degrees to the main stem. It flowers from June until September. It has 5 yellow ray florets.

Its main characteristic is an open airy clump of yellow flowers. Each flower is actually a composite flower, consisting of five petal-like flowers (strap or ray flowers), each approximately 5–7 mm (0.20–0.28 in) in length. There are no disc flowers.

Fruit

Fertile flowers are followed by short beaked, spindle shaped, achene’s that are approximately 0.13 in. (0.33 cm) long, several-nerved, and black or brown. The papas have simple white hairs, the inner longer than the outer that may disperse seeds long distances by wind.

Controlling Methods

It’s easy to pull it once you know how to spot it. Wear gloves, since the milky sap can irritate some people’s skin. Pull gently and firmly by the base of the stem and it should pop out; or use a trowel if you need leverage. If the plant has a flower or wispy seed heads, pull them off and put in a plastic bag for disposal; the rest of the plant can be composted, left on the ground to dry, or placed in a black plastic bag or a tarp to prevent re-growth.

References:

https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=503893#null
https://pfaf.org/user/Plant.aspx?LatinName=Lactuca+muralis
https://plants.usda.gov/core/profile?symbol=MYMU
https://en.wikipedia.org/wiki/Lactuca_muralis
https://www.invasiveplantatlas.org/subject.html?sub=13084
http://www.theplantlist.org/tpl1.1/record/gcc-116089
https://gd.eppo.int/taxon/MYLMU
https://gobotany.nativeplanttrust.org/species/mycelis/muralis/
https://cisma-suasco.org/invasive/wall-lettuce/

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