Lactuca biennis
Encyclopedia
Lactuca biennis is a species of wild lettuce
known by the common names tall blue lettuce and blue wood lettuce. It is native to the eastern half of the United States and Canada, but it can also be found in much of the western half as an introduced species
. This is a biennial herb in the daisy family
growing from a taproot
to heights anywhere from one half to four meters. There are deeply lobed, toothed leaves all along the stem. The top of the stem bears a multibranched inflorescence
with many flower heads
. Each head is just over a centimeter wide and has many whitish to light blue ray florets. The fruit is a mottled achene
about half a centimeter long with a brownish pappus
.
The species was described botanically in 1940.
Lactuca
Lactuca, commonly known as lettuce, is a genus of flowering plants in the daisy family Asteraceae. The genus includes about 100 species, distributed worldwide, but mainly in temperate Eurasia....
known by the common names tall blue lettuce and blue wood lettuce. It is native to the eastern half of the United States and Canada, but it can also be found in much of the western half as an introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
. This is a biennial herb in the daisy family
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
growing from a taproot
Taproot
A taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...
to heights anywhere from one half to four meters. There are deeply lobed, toothed leaves all along the stem. The top of the stem bears a multibranched inflorescence
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. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
with many flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
. Each head is just over a centimeter wide and has many whitish to light blue ray florets. The fruit is a mottled achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
about half a centimeter long with a brownish pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
.
The species was described botanically in 1940.