ANNUAL SOW THISTLE (Sonchus oleraceus) скачать в хорошем качестве

ANNUAL SOW THISTLE (Sonchus oleraceus)

How To Identify Annual Sow Thistle (Sonchus oleraceus) This is Annual Sow Thistle, a member of the Asteraceae family. It is native to Europe and is an invasive species around the world. It is an annual that flowers from spring to fall. The plant has a basal rosette of leaves, from which grows a tall, thin, fleshy stem. The stem is smooth and light green, and will develop a red or purple coloration over time. The leaves are highly variable and can make identification difficult. They are usually very deeply lobed, and have a distinct, large triangular tip, with fine teeth along their margin. The upper leaves lack a petiole and wrap around the stem, are usually unlobed and taper to a long, thin point, and have long, thin teeth along their margins. The leaves are smooth and hairless, and are light green with a faint bluish hue and will develop a reddish or purplish coloration. The plant has loose clusters of flower heads at the tops of its stems. The flower heads are about ¾ inches wide and are bright or pale yellow in color. The bracts have a distinct, vase-like shape, and the stalks and bracts may be sparsely covered in gland-tipped hairs. Once pollinated they will produce small balls of tufted seeds. The plant grows from a taproot and only reproduces via seed. The whole plant is filled with a milky latex sap. Annual Sow Thistle likes moist, disturbed soils, and prefers full sun but will tolerate shady areas. It is common in cultivated fields, gardens, orchards and vineyards, roadsides, and waste areas. The plant is edible and is eaten as a vegetable in some areas. Annual Sow Thistle can be difficult to distinguish from other closely-related sow thistle species with which it is often found growing alongside. In addition to this, all of the closely-related sow thistles will readily hybridize with each other. Perennial Sow Thistle has stiffer spines around the leaves, has a slightly different leaf shape, and lacks the distinctly-shaped sessile upper leaves. It has much larger and showier flowers and seed heads, and spreads via underground rhizome. It can easily be distinguished by the dense covering of gland-tipped hairs on the flower bracts and stalks. Prickly Sow Thistle has much stiffer, spinier leaves, and a large, stout stem. The flowers are identical, but the stalks and bracts are completely smooth and lack any of the gland-tipped hairs found on the other species. Prickly lettuce has fine, sharp prickles along the margin and midrib of its leaves, and can be easily differentiated once it flowers. Annual Sow Thistle is highly susceptible to various insect pests, and is often found covered in powdery mildew. It acts as a significant disease vector for many crops. 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