''Lactuca muralis'', the wall lettuce, is a
perennial
In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...
in the tribe
Cichorieae
The Cichorieae (also called Lactuceae) are a tribe in the plant family Asteraceae that includes 93 genera, more than 1,600 sexually reproductive species and more than 7,000 apomictic species. They are found primarily in temperate regions of the E ...
within the family
Asteraceae
Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...
. It is also referred to as ''Mycelis muralis''.
[Parnell, J. and Curtis, T. 2012. ''Webb's An Irish Flora''. Cork University Press. ]
Its chief characteristic is its open airy clumps of yellow flowers. Each "flower" is actually a composite flower, consisting of 4–5 petal-like flowers (strap or ray flowers), each approximately in length. There are no disc flowers. ''Lactuca muralis'' grows about tall with the lower leaves
pinnate
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and ...
ly toothed and clasping.
Description
''Lactuca muralis'' is slender, hairless herb
growing from tall. It often has purplish stems, and exudes a milky juice.
The lower leaves are lyre shaped, pinnate shaped. The lobes are triangular in shape, the terminal lobe being the largest.
[Clapham, A.R., Tutin, T.G. and Warburg, E.F. 1968 ''Excursion Flora of the British Isles Second Edition''. Cambridge] The upper leaves are stalkless, smaller and less lobed. All leaves are red tinged.
The achenes are short beaked, spindle shaped and black. The
pappus has simple white hairs,
the inner longer than the outer.
The flower heads are yellow, small with only 4–5 yellow ray florets.
wide more or less, on branches 90 degrees to the main stem, in loose panicle.
[Webb, D.A., Parnell, J. and Doogue. D. 1996. ''An Irish Flora''. Dundalgan Press (W. Tempest) Ltd. ] It flowers from June until September.
''Lactuca muralis'' is similar to ''
Lactuca serriola'' L. and ''
Lactuca virosa
''Lactuca virosa'' is a plant in the ''Lactuca'' (lettuce) genus, often ingested for its mild analgesic and sedative effects. It is related to common lettuce (''Lactuca sativa, L. sativa''), and is often called wild lettuce, bitter lettuce, lait ...
'' L. but clearly distinguished by having only 5 florets.
Taxonomy
The
specific Latin epithet ''muralis'' is interpreted as 'growing on walls'.
Distribution and ecology
''Lactuca muralis'' is a native of Europe but has invaded shady roadsides, paths and logged areas of the
Pacific Northwest
The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...
and New England It has become naturalized in parts of
Northern Ireland
Northern Ireland ( ; ) is a Countries of the United Kingdom, part of the United Kingdom in the north-east of the island of Ireland. It has been #Descriptions, variously described as a country, province or region. Northern Ireland shares Repub ...
as long ago as 1913.
[Hackney, P. Ed. 1992. ''Stewart and Corry's Flora of the North-east of Ireland''. Institute of Irish Studies and The Queen's University of Belfast. (HB)] It was first recorded in
The Burren
The Burren ( ; ) is a karst/glaciokarst landscape centred in County Clare, on the west coast of Republic of Ireland, Ireland. , where it is now frequent, in 1939.
It can be found in woodlands, especially
Beech
Beech (genus ''Fagus'') is a genus of deciduous trees in the family Fagaceae, native to subtropical (accessory forest element) and temperate (as dominant element of Mesophyte, mesophytic forests) Eurasia and North America. There are 14 accepted ...
.
It is also found in calcareous soils, and walls.
References
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{{Taxonbar, from1=Q15629257, from2=Q1546483
muralis
Flora of Europe
Plants described in 1753
Taxa named by Carl Linnaeus