(L.) Gaertn. 1791 not Fresen. 1832
Its chief characteristic is an 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 5–7 mm in length. There are no disc flowers. Lactuca muralis grows about 2–4 feet tall with the lower leaves pinnately toothed and clasping.
Lactuca muralis is slender, hairless herb growing from 25 to 150 cm 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 upper leaves are stalkless, smaller and less lobed. All leaves are red tinged.
The flower heads are yellow, small with only 4-5 yellow ray florets.1 cm wide more or less, on branches 90 degrees to the main stem, in loose panicle. It flowers from June until September. Lactuca muralis is similar to Lactuca serriola L. and Lactuca virosa L. but clearly distinguished having only 5 florets.
Distribution and ecology
Lactuca muralis is a native of Europe but has invaded shady roadsides, paths and logged areas of the Pacific Northwest. It has become naturalized in parts of Northern Ireland as long ago as 1913.
- Tropicos, Lactuca muralis (L.) Gaertn.
- Parnell, J. and Curtis, T. 2012. Webb's An Irish Flora. Cork University Press. ISBN 978-185918-4783
- Altervista Flora Italiana, Lactuca muralis (L.) Gaertn. includes photos and European distribution map
- Blamey, Fitter, Fitter, Marjorie, Richard, Alistair (2003). Wild Flowers of Britain and Ireland. A & C Black - London. pp. 302–303. ISBN 0-7136-5944-0.
- Sterry, Paul (2006). Complete British Wild Flowers. HarperColins Publishers Ltd. pp. 212–213. ISBN 978-0-00-781484-8.
- Webb, D.A., Parnell, J. and Doogue. D. 1996. An Irish Flora. Dundalgan Press (W. Tempest) Ltd. ISBN 0 85221 131 7
- Rose, Francis (1981). The Wild Flower Key. Frederick Warne & Co. pp. 390–391. ISBN 0-7232-2419-6.
- Martin, W.K.1965. The Concise British Flora in Colour Ebury Press
- Archibald William Smith A Gardener's Handbook of Plant Names: Their Meanings and Origins, p. 160, at Google Books
- Turner and Gustafson, Wildflowers of the Pacific Northwest.
- 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. ISBN 0 85389 446 9(HB)
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