Japanese name: トゲチシャ（刺萵苣） Scientific name:Lactuca serriola
[Overview]
An annual or biennial 1–2 m tall, found on waste ground and roadsides.
There are many fine prickles on the lower part of the stem, on the leaf margins, and on the midrib on the underside of the leaves.
The stem is erect and tinged with red.
There are basal leaves and stem leaves; the basal leaves are obovate-oblong, 15 cm long and 5 cm wide, and pinnately lobed.
The stem leaves are alternate, oblanceolate to oblong and pinnately lobed, with the leaf base spreading sideways to clasp the stem.
The leaf margins are toothed.
The leaf base is twisted, so the leaves stand vertically (with the margins facing up).
The stem branches in the upper part and bears many flower heads.
The flower heads are 1–1.5 cm across, cream to pale yellow, and consist of 15–25 ray florets.
The fruit is an achene with a pappus.
[History]
It was collected in Otaru, Hokkaido in 1949 and has since become naturalized in various places.
