PRICKLY LETTUCE (Lactuca serriola) скачать в хорошем качестве

PRICKLY LETTUCE (Lactuca serriola)

How to identify Prickly Lettuce (Lactuca serriola) This plant is commonly called prickly lettuce. It is a member of the sunflower family Asteraceae, and is native to Eurasia and north Africa. It has become naturalized around much of the world, and is very common in almost all of north America. It is a biennial that blooms from mid to late summer. The plant grows as a single, tall, thin stem. The stem is usually tinted brownish red and is covered in rows of thin prickles. The leaves of this plant can be oblong and smooth on the lower portion of the stem, but become large and very strongly toothed. They are dark green in color, with a distinct light green to cream colored midrib and veins. The margin and midrib are covered in neat rows of thin prickles. Flowers are small, about one quarter to half an inch in size, and bright yellow in color. They appear on thin, irregularly branched stalks which form from the midpoint or the top of the main plant stem, each small branch topped with a single flower head. The seed heads are small balls of parachuted seeds. This plant only reproduces via seeds, and grows from a deep, thin taproot. The whole plant is filled with a milky white latex sap. Occasionally the plant will have a smooth, light green stem, as opposed to a reddish stem with prickles. This plant prefers strong full or partial sun, and grows in disturbed but relatively stable soil and likes moisture. It is very common in waste sites, gardens, and along roadsides and buildings. This plant tends to punch through thick bedding materials. This plant orients its leaves along a north-south axis as means of avoiding damage from the midday sun, and thus can be used as a reliable compass. Young plants are edible, but will become mildly toxic after they mature. Prickly lettuce is closely related to wild lettuce, Lactuca virosa, but can be easily distinguished by its deeply lobed leaves and full covering of prickles, which wild lettuce lacks. Perennial Sow thistle (Sonchus arvensis) is a weed which looks very similar and can be easily confused with prickly lettuce. However, Sow thistle lacks the prickles on the leaf midrib that is found on prickly lettuce, and is generally a much paler green in color. In addition, Sow thistle spreads using rhizomes, which prickly lettuce does not possess. Sources: Weeds of the West, 5th Edition (1991) by Tom D. Whitson, published by the Western Society of Weed Science University of California Agriculture and Natural Resources IPM – Weed Gallery http://ipm.ucanr.edu/ United States Department of Agriculture – Plant Database https://plants.usda.gov