Senecio vulgaris, often known by the common names groundsel and old-man-in-the-spring, is a flowering plant in the family Asteraceae. It is an annual herb, native to the Palaearctic and widely naturalised as a ruderal species in suitable disturbed habitats worldwide.
Halogeton glomeratus is a species of flowering plant in the family Amaranthaceae known by the common names saltlover, Aral barilla, and halogeton. It is native to Russia, Central Asia and China, but the plant is probably better known in the western United States, where it is an introduced species and a notorious noxious weed. This annual herb is a hardy halophyte, thriving in soils far too saline to support many other plants. It also grows in alkali soils such as those on alkali flats and disturbed, barren habitat. It can be found in sagebrush and shadscale habitat, and it grows well in areas with cold winters.
Rumex acetosella, commonly known as red sorrel, sheep's sorrel, field sorrel and sour weed, is a species of flowering plant in the buckwheat family Polygonaceae. Native to Eurasia and the British Isles, the plant and its subspecies are common perennial weeds. It has green arrowhead-shaped leaves and red-tinted deeply ridged stems, and it sprouts from an aggressive and spreading rhizome. The flowers emerge from a tall, upright stem. Female flowers are maroon in color.
Erigeron canadensis is an annual plant native throughout most of North America and Central America. It is also widely naturalized in Eurasia and Australia. Common names include horseweed, Canadian horseweed, Canadian fleabane, coltstail, marestail, and butterweed. It was the first weed to have developed glyphosate resistance, reported in 2001 from Delaware.
Carduus pycnocephalus, with common names including Italian thistle, Italian plumeless thistle, and Plymouth thistle, is a species of thistle. It is native to: the Mediterranean region in southern Europe, North Africa, and Western Asia; East Europe and the Caucasus; and the Indian Subcontinent.
Pilosella caespitosa is like several other Pilosella species and has a similar appearance to many of the hawkweeds.
Carduus tenuiflorus, known variously as slender-flower thistle, sheep thistle, shore thistle, slender thistle, winged plumeless thistle, winged slender thistle and winged thistle, is a species of flowering plant in the family Asteraceae. It is native to Europe and North Africa, and an introduced species elsewhere.
Chorispora tenella is a species of flowering plant in the mustard family known by several common names, including purple mustard, blue mustard, musk mustard, and crossflower. This mustard is native to parts of Eurasia but is well known in other parts of the world, particularly in temperate regions, as an introduced species and a noxious weed.
Crupina is a small genus of plants in the tribe Cardueae within the family Asteraceae.
Helianthus ciliaris is a species of sunflower known by the common names Texas blueweed and yerba parda.
Leontodon saxatilis is a species of hawkbit known by the common names lesser hawkbit, rough hawkbit, and hairy hawkbit. It is native to Europe and North Africa but can be found in many other places across the globe as an introduced species and often a noxious weed. This is a dandelion-like herb growing patches of many erect, leafless stems from a basal rosette of leaves. The leaves are 2 to 15 centimeters long, 0.5 to 2.5 centimeters wide, entire or lobed, and green in color. Atop the stems are solitary flower heads which are ligulate, containing layered rings of ray florets with no disc florets. The florets are yellow with toothed tips. The fruit is a cylindrical achene with a pappus of scales. Fruits near the center of the flower head are rough, while those growing along the edges of the head are smooth.
Ambrosia confertiflora is a North American species of ragweed known by the common name weakleaf bur ragweed.
Helminthotheca echioides, known as bristlyoxtongue, is a sprawling annual or biennial herb native to Europe and North Africa. It was originally placed within the genus Picris but is often separated within the small genus Helminthotheca alongside a few other plants which also have the distinctive outer row of bracts around the flowerheads. It is a ruderal plant, found on waste ground and agricultural soils around the world, and in some places it is considered a troublesome weed.
Lappula squarrosa is a species of flowering plant in the borage family known by several common names, including European stickseed, bur forget-me-not, bluebur, and bristly sheepbur. It is native to Europe and Asia, where it is common, and it is an introduced species in much of North America and Africa. It is well known as a noxious weed where it is naturalized and also in many parts of its native range. This is an annual herb producing an erect stem often with sprays of many long, bending branches, its form varying in different regions and climates. The plant may approach a meter in height. The stems are lined with linear to oval leaves up to 5 centimeters long and coated in whitish hairs, and the herbage emits a scent generally considered unpleasant. The inflorescence is a long, leafy raceme of tiny flowers near the ends of the branches. Each flower is 2 to 4 millimeters wide with five light blue corolla lobes. White-flowered plants are occasionally seen. The fruit is a cluster of four nutlets which are coated in hooked prickles. The seeds are dispersed when the prickles get caught on animal coats and human clothing, and when they are moved by wind.
Lessingia arachnoidea is a rare species of flowering plant in the family Asteraceae known by the common name Crystal Springs lessingia. It is endemic to California, where it is known from a few occurrences in the vicinity of Crystal Springs Reservoir on the San Francisco Peninsula and southward to serpentine soil in Woodside. It may also exist in Sonoma County to the north. The plant grows in chaparral, scrub, grasslands and other local plant communities, on serpentine soils.
Kyhosia is a monotypic genus of flowering plants in the family Asteraceae containing the single species Kyhosia bolanderi, which is known by the common names Bolander's madia and kyhosia.
Jensia yosemitana is a species of flowering plant in the family Asteraceae known by the common name Yosemite tarweed. It is endemic to California, where it has a scattered distribution across the Sierra Nevada and its foothills. Some of the populations lie inside Yosemite National Park.
Xanthium spinosum is a species of flowering plant in the aster family known by many common names, including spiny cocklebur, prickly burweed and Bathurst burr. This species is part of the genus Xanthium that encompasses 25 different species of flowering plants of the daisy family, Asteraceae, and sunflower tribe.
Centaurea macrocephala is a species of flowering plant in the family Asteraceae, and a member of the thistle tribe, Cynareae. It has many common names, including bighead knapweed, big yellow centaurea, lemon fluff, yellow bachelor's button, yellow hardhat, and Armenian basketflower.
Meadow knapweed is a fertile hybrid between black knapweed and brown knapweed. It is also known by the common names of hybrid knapweed or protean knapweed. The taxonomic status of the species is uncertain, and meadow knapweed has been variously described as different species. The Flora of North America refers to meadow knapweed as the nothospecies Centaurea × moncktonii.
