''Lactuca ludoviciana'', the biannual lettuce, is a North American species of

wild lettuce Wild lettuce is a common name for several lactucarium-containing plants related to lettuce (''Lactuca sativa''). The name most often refers to ''Lactuca virosa'' (Europe, Asia, introduced to North America), though it may also refer to: * ''Lactuc ...

. It is widespread across much of central and western Canada and the western and central United States from

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

west to

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

and south to

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, and

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

. Most of the known populations are on the

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

; populations west of there may well represent naturalizations. ''Lactuca ludoviciana'' is a biennial herb in the dandelion tribe within the daisy family growing from a

taproot A taproot is a large, central, and dominant root from which other roots sprout laterally. Typically a taproot is somewhat straight and very thick, is tapering in shape, and grows directly downward. In some plants, such as the carrot, the taproo ...

a height of up to 150 cm (5 feet). The top of the stem bears a multibranched

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

with many

flower heads A pseudanthium (Greek for "false flower"; ) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, compos ...

. Each head contains 20-50 yellow ray florets but no disc florets. It has been seen to

hybridize Hybridization (or hybridisation) may refer to: *Hybridization (biology), the process of combining different varieties of organisms to create a hybrid *Orbital hybridization, in chemistry, the mixing of atomic orbitals into new hybrid orbitals *Nu ...

wildly with ''

Lactuca canadensis ''Lactuca canadensis'' is a species of wild lettuce known by the common names Canada lettuce, Canada wild lettuce, tall lettuce, and Florida blue lettuce.Weakley, Alan S''. Flora of the Southern and Mid-Atlantic States.'' UNC Herbarium, North Car ...

'', and it is difficult to differentiate between the two species.

References

External links

Photo of herbarium specimen at Missouri Botanical Garden, collected in Missouri in 1893
ludoviciana Flora of North America Plants described in 1818 {{Cichorieae-stub