Chorizanthe polygonoides is a species of flowering plant in the buckwheat family known by the common name knotweed spineflower. It is native to California and Baja California, where it grows widely scattered in many types of habitat. It is a petite plant taking a prostrate form with stems just a few centimeters long at maximum. It may be green to red in color and is hairy in texture. The leaves are no more than a centimeter long and the flower is under two millimeters wide. The minute flower is surrounded by three hairy point-tipped bracts.

Chorizanthe procumbens is a species of flowering plant in the buckwheat family known by the common name prostrate spineflower. It is native to California and Baja California, where it grows in scrub and chaparral habitat. It is variable in appearance, up to 25 centimeters long or much shorter, usually growing prostrate along the ground. It is often yellowish green in color but there are grayish and reddish forms. The inflorescence is a cluster of flowers with each minute white or yellow flower surrounded by spine-tipped bracts.

Chorizanthe pungens is a species of flowering plant in the buckwheat family known by the common name Monterey spineflower. It is endemic to California, where it is known from the San Francisco Bay Area south along the Central Coast. It grows mainly in coastal habitat and that of the hills and mountains overlooking the coastline. This is a generally erect but sometimes spreading or prostrate plant with stems up to half a meter in length. It is green to gray to red in color and usually hairy in texture. The leaves are located at the base of the plant; there are also bracts along the stem at the bases of the inflorescences which look like leaves. The inflorescence is a dense cluster of flowers, each flower surrounded by six white to pink hairy bracts tipped in hooked awns. The flower itself is only a few millimeters wide with jagged tepals. Varieties: There are two varieties of this species:var. pungens is the more commonvar. hartwegiana is known only from the Santa Cruz Mountains north of Santa Cruz. This variety, known as the Ben Lomond spineflower, is treated as a federally listed endangered species. It is found in the same type of unique habitat, known as the Zayante sandhills, as other local rare endemic life forms such as the Ben Lomond wallflower Erysimum teretifolium and the Zayante band-winged grasshopper Trimerotropis infantilis. Threats to this plant and other endemic species include the destruction of the local habitat during sand mining.

Chorizanthe rectispina is a species of flowering plant in the buckwheat family known by the common names prickly spineflower and straight-awned spineflower. It is endemic to California, where it is known from about twenty occurrences from Monterey to Santa Barbara Counties. It grows in dry habitat types such as chaparral and woodland in the hills of the Central Coast Ranges. It is a low, spreading plant with stems up to about 25 centimeters long, grayish to greenish in color and hairy in texture. The inflorescence is a cluster of flowers, each flower surrounded by six hairy bracts which are grayish to pink in color and tipped with awns. One bract is longer than the others and has a straight awn, and the other smaller bracts may have hooked awns. The tiny flower at the center of the bract array is a few millimeters wide and white and yellow in color.

Chorizanthe rigida, with the common names of devil's spineflower, rigid spineflower, spiny-herb, rigid spiny-herb, is an annual plant in the Polygonaceae family the buckwheats. It is a member of the genus Chorizanthe, the spineflowers and is found in the southwestern United States and northwest Mexico, in the states of California, Nevada, Utah, Arizona, Baja California, and Sonora. Chorizanthe rigida is a common desert plant found in the Sonoran and Mojave Desert - in bajadas (washes), flat mesas that flood with annual rains, and rocky hillsides and ridgelines. A locale range example is its presence in most habitats of the Muggins Mountains Wilderness in southeastern Arizona. In desert flats, the short 3 inch plant can be easily obscured, by downstream-washed debris that easily collects on the spineflower skeleton. Thus small hillocks of debris are found, a spineflower in the core; possibly this is the advantageous form of germinating at least the source location into a second generation. In flat mesas the plant can be hidden under clumps and not seen. On a roadside, its skeleton will be left as a single erect plant, the taller plants being found in the highest water-pooled areas.

Chorizanthe robusta is a species of flowering plant in the buckwheat family. It is endemic to California, where it is a rare, federally listed endangered species. C. robusta is variable in form, growing decumbent or erect and reaching a maximum length of half a meter. It is grayish in color and hairy. The inflorescence is made up of several flowers with each flower surrounded by white or pink bracts with hooked tips. The flower itself is just a few millimeters long and white to pink in color. Varieties: It is composed of two varieties:var. robusta, known generally as the robust spineflower, which is known only from southern Santa Cruz and Monterey Counties,var. hartwegii, the Scotts Valley spineflower, which is known from a few locations in Scotts Valley in Santa Cruz County. The plant is closely related to Chorizanthe pungens, another rare endemic from the area.

Chorizanthe spinosa is an uncommon species of flowering plant in the buckwheat family known by the common name Mojave spineflower. It is endemic to California, where it is known only from the scrub habitat at the western edges of the Mojave Desert. Chorizanthe spinosa is prostrate or upright, reaching up to 40 centimeters in length. It is grayish in color and hairy in texture. The inflorescence is an open or dense cluster of flowers, with each flower surrounded by green, gray, or pink bracts. There are generally five bracts per flower, with one bract much longer than the others. The bracts are tipped with straight awns. The flower at the center is only about 3 millimeters wide and usually white in color.

Chorizanthe staticoides is a species of flowering plant in the buckwheat family known by the common name Turkish rugging. It is endemic to California, where it is a common member of the flora in the chaparral and scrub habitats in a number of regions. This is a plant which is quite variable in morphology, producing small patches on the ground or growing erect to heights over half a meter. The leaves measure from just a few millimeters to about 8 centimeters long. Most of them grow at the base of the fuzzy green or reddish stem. The top of the stem branches neatly into flat-topped flower clusters packed densely with tiny flowers. Each flower has a cylindrical base of six sharp-tipped leafs in shades of red to purple or green. Within this involucre is the pink to red flower which is a few millimeters wide and contains nine tiny stamens.

Chorizanthe stellulata is a species of flowering plant in the buckwheat family known by the common name starlet spineflower. It is endemic to California, where it grows in the dry woodlands of the low mountains and foothills along the central part of the state, such as the Sierra Nevada foothills. The plant takes an erect form, reaching up to 30 centimeters tall. The leaves are located at the base of the plant, and there is also a whorl of leaves at mid-stem. The inflorescence is a dense cluster of flowers, each flower surrounded by hairy, bristly white bracts tipped with hooked awns. The flower is 4 or 5 millimeters long and white to pink in color.

Chorizanthe uniaristata is a species of flowering plant in the buckwheat family known by the common name one-awn spineflower. It is endemic to central California, where it is known from several of the local mountain ranges, as well as the Central Coast. It grows in sandy, gravelly, and rocky soils in chaparral and woodland. This plant has upright or decumbent stems up to about 25 centimeters in length. It is hairy and gray, green, or reddish in color. The inflorescence is a cluster of flowers, with each flower surrounded by an array of six hairy bracts. One bract is much longer than the others and has a long, straight awn; the other bracts have hooked awns. The flower is 2 or 3 millimeters long and usually white.

Chorizanthe valida is a rare species of flowering plant in the buckwheat family known by the common name Sonoma spineflower. It is endemic to West Marin, Marin County, California, where it is known from only one remaining natural population at Point Reyes National Seashore. It was thought to be extinct until 1980 when the Point Reyes population was discovered. Chorizanthe valida is a federally listed endangered species.

Chorizanthe ventricosa, common name Priest Valley spineflower, is a plant species endemic to a small region in the Coastal Ranges of west-central California. It is found only on serpentine outcrops in grasslands and pine-oak woodlands at elevations of 500-1000 m. It has been reported from 4 counties: Monterey, San Benito, Fresno and San Luis Obispo. Chorizanthe ventricosa is an herb up to 70 cm tall, forming large spreading colonies. Leaves are up to 5 cm long. Flowers are formed in clusters up to 6 cm across, with green bracts with pointed tips giving the impression of spines. Flowers are 2-colored, white or yellow plus red or maroon.

Chorizanthe watsonii is a species of flowering plant in the buckwheat family known by the common name fivetooth spineflower. It is native to the western United States from Washington to the Mojave Desert. It grows in many types of plant communities from desert scrub to woodland and sagebrush. This small plant grows a woolly erect stem up to about 15 centimeters tall. The inflorescence is a cluster of flowers surrounded by five hairy greenish bracts tipped with hooked awns. The flower is about 2 millimeters wide and yellow in color.

Chorizanthe wheeleri is a rare species of flowering plant in the buckwheat family known by the common names Santa Barbara spineflower and Wheeler's spineflower. It is endemic to Santa Cruz and Santa Rosa Islands, two of the Channel Islands of California. It resembles the closely related plant known as Turkish rugging (Chorizanthe staticoides) and any reported mainland occurrences are actually specimens of this much more common species.

Chorizanthe xanti is a species of flowering plant in the buckwheat family known by the common name Riverside spineflower. It is endemic to California, where it grows in several of the mountain ranges from the Sierra Nevada to the Southern California Transverse Ranges in forest, woodland, and scrub habitats. Chorizanthe xanti is generally erect in form, reaching up to about 30 centimeters in height, and reddish in color and coated in thin to dense hairs. The inflorescence is a loose cluster of flowers, each flower surrounded by six reddish, curly-haired bracts tipped with hooked awns. The flower is up to 6 millimeters wide and pink to red in color. There are two varieties of this species. Chorizanthe xanti is generally erect in form, reaching up to about 30 centimeters in height, and reddish in color and coated in thin to dense hairs. The inflorescence is a loose cluster of flowers, each flower surrounded by six reddish, curly-haired bracts tipped with hooked awns. The flower is up to 6 millimeters wide and pink to red in color. There are two varieties of this species. The rarer, var. leucotheca, is known only from the San Jacinto and San Bernardino Mountains. It has a much more thickly woolly inflorescence than the more common variety.

Chrysolepis chrysophylla is a species of flowering plant in the beech family known by the common names golden chinquapin, giant chinquapin, and western chinquapin. It is native to the Pacific coast of the United States from west-central Washington to central California. This plant is a shrub or tree. Shrubby forms of the plant occur in dry areas, higher elevations, and poor soils. The plant grows into a tree up to 45 metres (148 ft) tall in cooler, moister areas such as valley bottoms and north-facing slopes, and foggy and rainy areas. The bark is thin and smooth on young trunks; on older specimens it becomes thicker and platy. The open crown of the large tree is conical in shape. The leathery evergreen leaves are dark green on the upper sides and golden underneath. The leaves are folded upward along the midrib. The species is monoecious, with individuals bearing both male and female flowers. White male flowers are borne in the leaf axils, and a cluster of female flowers is borne beneath them. A spiny bur contains one to three nuts. There is generally a burl at the base of the tree. The tree may sprout from adventitious buds in the burl, a form of vegetative reproduction that is more common in dry areas where it is less likely that seedlings would become established. The tree may live up to 500 years.

Golden Chinquapin (Chrysolepis chrysophylla var. chrysophylla) is a native tree or shrub that grows in central and northern California. It is moderately fast growing and long-lived. It grows in an upright form to a height of 100 feet, with active growth during the spring and summer. Flowers are yellow and bloom in the mid spring. Leaves are medium green, and remain on the plant throughout the year. It tends to grow at elevations from 0-6600 feet.

Giant Chinquapin (Chrysolepis chrysophylla var. minor) is a native tree or shrub that grows in central and northern California. It tends to grow at elevations from 0-5900 feet.

Bush Chinquapin (Chrysolepis sempervirens) is a native shrub that grows in northern, southern and central California. It is slow growing and moderately long-lived. It grows in a semi-upright form to a height of 7 feet, with active growth during the spring and summer. Flowers are green and bloom in the mid summer. Leaves are medium green, and remain on the plant throughout the year. It tends to grow in rocky slopes, at elevations from 2500-11000 feet.

Long Flowered Rabbitbrush (Chrysothamnus depressus) is a native shrub that grows in Southern California, primarily in the Desert Mountains and Mojave Desert regions. It tends to grow in rocky crevices, at elevations from 3300-6900 feet.

Chrysothamnus greenei called Greene' rabbitbrush , is a North American species of flowering plants in the aster tribe within the sunflower family. It has been found in eastern California (Mono + Inyo Counties), Nevada, Arizona, New Mexico, Utah, Colorado, and southern Wyoming (Sweetwater County). Chrysothamnus greenei is a branching shrub up to 50 cm (20 inches) tall with gray bark. It has many small, yellow flower heads clumped into dense arrays. The species grows in sandy locations in desert regions.

Chrysothamnus viscidiflorus is a species of shrub in the daisy family known by the common names yellow rabbitbrush and green rabbitbrush. It is native to western North America, from British Columbia to California to Nebraska, where it grows in sagebrush and woodland habitat. It grows easily in alkaline and saline soils, and thrives on soils that are rich in calcium. It rapidly establishes in disturbed habitat, including burns, flooded washes, and rockslides, so it is a valuable shrub for revegetating damaged land such as overgrazed rangeland and abandoned mining areas. This shrub grows up to about 1.5 meters in height with spreading brittle pale-colored stem branches. The leaves are up to a few centimeters long and may be thin and thready or up to a centimeter wide and oblong in shape. They are hairy, resinous, and sticky. The flower cluster is a bushy cluster of flower heads, each head one half to one centimeter long. The flower head is lined with sticky yellow-green phyllaries and contains several yellowish protruding flowers. The fruit is a hairy achene a few millimeters long with a wispy pappus at the tip.

Chylismia brevipes is a species of wildflower in the Onagraceae (Evening Primrose) family that is native to the American desert southwest. It is known by the common names Yellow Cups, Mojave Suncup, and Golden Suncup. This is a hairy annual with tall stems often reaching over half a meter in height and surrounded by basal leaves which may be simple or composed of several leaflets. It produces an flower cluster which has one to several blooms in it. The flowers are bright yellow, often with reddish speckling at the base of each petal. The center of the flower has a long pistil and several shorter stamens with large anthers. The fruits are hanging capsules which may be several centimeters long.

Golden Suncup (Camissonia brevipes ssp. brevipes) is a native annual herb that grows in Southern and Central California, primarily in the Desert Mountains, the Mojave Desert and Sonoran Desert regions. It tends to grow in sandy or rocky slopes, at elevations from 0-5900 feet.

Cicuta douglasii (Western water hemlock) is a poisonous plant in the family Apiaceae. It is a perennial plant that grows in wet places such as marshes, stream banks, slough margins, ditches, meadows, and wet pastures. The roots of this plant are thick and tuberous, with many smaller tubers coming from the main tuber. This root structure allows the water hemlock to adapt and survive wet conditions. Water hemlock is most abundant in British Columbia, and is indigenous to North America. In North America it primarily grows from the base of the Rocky Mountains to the Pacific coast, stretching all the way from Alaska down to California. Water necessities limit this plant from growing in open rangelands. The characteristics of water hemlock include its stem which is 0.5-2 meters tall with purplish spots, thick roots, and leaves that are compound pinnate and alternate. The leaflets are usually 5-8 centimeter long and 1-2 centimeter wide with jagged edges. The flowers on it are compound umbellate flower clusters with many small, white flowers. There are two seeds for each flower. Seed dispersal for water hemlock seeds comes from means of wind, water, machinery, on clothing, and through transported soil. The seeds germinate in spring, and flowers mature near the end of June and beginning of July. In addition to sprouting new plants from seeds, rootstocks can also product new plants. These are formed in the fall from the basal meristem, and when they detach the following spring, they may form a new plant.

Cicuta maculata is a species of flowering plant in the carrot family known by several common names, including spotted water hemlock, spotted parsley, and spotted cowbane. It is native to nearly all of North America, from northern Canada to southern Mexico. This is a rhizomatous perennial herb producing a hollow erect stem to a maximum height between 1 and 1.5 meters. The long leaves are made up of several lance-shaped, pointed, serrated leaflets. Each shiny green leaflet is 2 to 10 centimeters long and the entire leaf may be up to 40 centimeters long. The flower cluster of white flowers is similar in appearance to many other species in the carrot family. It is a compound umbel with a many clusters of flowers. The dry tan-brown fruit is a few millimeters long. The plant is occasionally mistaken for parsnips, due to its clusters of white tuberous roots; this is an often fatal error, as the Cicuta is extremely poisonous. Indeed, spotted water hemlock is considered to be North America's most toxic plant. Cicuta is fatal when swallowed, causing violent and painful convulsions. Though a number of people have died from water hemlock poisoning over the centuries, livestock have long been the worst affected (hence the name "cowbane"), causing death in as little as 15 minutes.

Cirsium andrewsii is an uncommon species of thistle known by the common name Franciscan thistle. It is endemic to California, where it is known from the coastline of the San Francisco Bay Area from Marin to San Mateo Counties. There are also reports of isolated populations in the Klamath Mountains and in the Sierra Nevada. Cirsium andrewsii grows in coastal habitats such as sea bluffs and canyons, and is sometimes found on serpentine soils. The species is biennial to perennial, producing an erect, leafy stem which can reach two meters in height. It is highly branched, dense to clumpy, fleshy, and cobwebby with fibers, especially when new. The leaves are woolly or cobwebby, spiny along the edges, and sometimes lack lobes or deep cuts. They are borne on petioles with winged, spiny margins, some spines exceeding a centimeter in length. The inflorescence produces one or more flower heads, each up to 3 centimeters long by 5 wide, wispy with cobwebby fibers, and lined with very spiny phyllaries. The flower head is packed with dark purplish-pink flowers up to about 2. 5 centimeters in length. The fruit is an achene with a dark brown body about half a centimeter long and a pappus about 1. 5 centimeters long.

Cirsium arizonicum (Arizona thistle) is a North American species of thistle in the sunflower family, native to the southwestern United States and northwestern Mexico. It has been found in Arizona, southeastern California, New Mexico, Nevada, Colorado, Utah, Sonora, and northwestern Chihuahua. Cirsium arizonicum is a herbaceous plant that can be either biennial or perennial, reaching 30-150 cm in height. The spiny leaves are oblong-obovate with pinate lobes; the basal leaves are larger, 10-40 cm long, while leaves on the upper stem can be only 3 cm long. The inflorescence is 3-4 cm in length and 1. 5-2 cm diameter, red to pink or purple, with all the florets of similar form (no division into disc and ray florets); individual plants are very variable in the number of heads produced, from one to 100. Flowering is from mid spring to mid fall. The species occurs in mountains, at elevations of 900-3,600 m.

Cirsium brevistylum is a species of thistle known by the common names Indian thistle and clustered thistle. It is native to western North America from southwestern British Columbia to California, where it grows in moist areas in many types of habitat, from mountain forests to chaparral and coastal marshes. This native thistle is annual or biennial, reaching two meters in height and known to exceed three meters at times. There is usually a single stem which may branch toward the top and is coated in hairs and webby fibers. The leaves are deeply cut into many lobes lined with twisted teeth, the longest leaves near the base of the plant reaching about 25 centimeters long. The leaves are borne on winged petioles with many spines. The flower cluster bears one to many flower heads, both at the ends of the stem branches and in the leaf axils. The flower head reaches about 3 centimeters long by 4 wide and is lined with cobwebby, bristly, spine-tipped phyllaries. The flower head is packed with white or pink flowers about 2 centimeters long. The fruit is a brown achene a few millimeters long topped with a pappus one to two centimeters in length.

Cirsium ciliolatum is a species of thistle known by the common name Ashland thistle. It is endemic to the Klamath Mountains, where it is known from only a few occurrences in Jackson and Josephine Counties in Oregon, as well as neighboring Humboldt and Siskiyou Counties in California. It is related to Cirsium undulatum and may be more accurately described as a variety of that species. Cirsium ciliolatum is a perennial herb growing from a rootstock branching with runner roots to a maximum height near 200 cm (79 in). It is cobwebby with fibers. The gray-green woolly leaves are smooth along the edges to deeply lobed, sometimes spiny and cobwebby, and up to 25 centimeters at the longest. The inflorescence is a cluster of several flower heads each about 2 centimeters long and up to 5 wide. The head is lined with sticky, spiny phyllaries and packed with white to lavender flowers. The fruit is an achene with a thick body a few millimeters long and a pappus about 1. 5 centimeters in length.

Cirsium crassicaule is a species of thistle known by the common name slough thistle. It is endemic to the San Joaquin Valley of California, where it is known primarily from freshwater wetlands. It has been found in only a few locations in Kern, Kings, and San Joaquin Counties. Cirsium crassicaule is an annual or biennial herb known to reach 300 cm (10 feet) in height. The thick stem is hollow and may be nearly 10 centimeters (4 inches) wide at the base. It is coated in hairs and cobwebby fibers. The woolly, webby, spiny leaves are deeply cut into many lobes, the lobes often lined with teeth. The longest leaves near the base of the plant may be 70 centimeters (28 inches) long.

Cirsium cymosum is a North American species of thistle known by the common name peregrine thistle. It is native to the western United States, where it has been found in California, Oregon, Nevada, Utah, Idaho, Wyoming, and Montana. Cirsium cymosum is a biennial or perennial herb with a maximum height just 100 cm (39 in). It is coated in soft and coarse hairs and sometimes cobwebby fibers. The spiny leaves may reach 30 to 50 centimeters (12 to 20 inches) in length, especially toward the base of the stem. They are deeply cut into lobes which are lined with sharp teeth. The inflorescence is a cluster of flower heads each up to 3 centimeters long and 5 wide. The head is lined with sticky, spiny phyllaries and filled with dull white flowers. The fruit is an achene with a dark-colored body just under a centimeter long and a pappus of hairs up to 2. 5 centimetres (0. 98 inches) in length.

Cirsium douglasii is a species of thistle known by the common names Douglas' thistle and California swamp thistle. It is native to the central coast and northern California ranges, foothills, and plateaus, and adjacent parts of southern Oregon and northwest Nevada. It grows in wet places in a number of types of habitat. This native thistle, Cirsium douglasii, is a biennial or short-lived perennial herb growing up to 2. 5 metres (8. 2 ft) tall, with a branching woolly stem. The longest gray-tomentose leaves, located about the base of the plant, are up to 1 metre (3. 3 ft) long. They are sometimes lobed or toothed and are borne on a spiny petiole. The inflorescence is a cluster of several flower heads surrounded by small leaves. Each flower head is up to 3 centimetres (1. 2 in) long and lined with purple-tipped spiny phyllaries. The head contains purple or white flowers. The fruit is a dark-colored achene 2-4. 5 millimetres (0. 079-0. 177 in) long/diameter with a pappus which may reach 2 centimetres (0. 79 in) in length. VarietiesCirsium douglasii var. breweri (A. Gray) D. J. Keil & C. E. Turner - California, Oregon, NevadaCirsium douglasii var. douglasii - California

Cirsium fontinale or Fountain thistle is an flowering perennial herb of the Asteraceae family, endemic to a limited region within northern and central California at an elevation not exceeding 750 meters. Occurrences appear limited to serpentine seeps and streams within portions of the San Francisco Bay Area and Outer South Coast Ranges. The Cirsium genus is commonly known as the "thistle" genus, Cirsium being the Greek word for thistle. There are three recognized varieties of this species: All the taxa within Cirsium fontinale have erect stems with leaves very strongly wavy margins. These tall plants may attain a height of 2.2 meters, but may exist in the form of only 0.5 meters. A given plant may have one or more stems, and the plants are sometimes short-lived, dying after flowering only once, even though the species is acknowledged to be perennial. Lower leaves are typically petioled or tapered, but mostly spiny-lobed; petioles are either spiny-lobed or toothed.

Cirsium hydrophilum is a species of thistle which is endemic to California, where it is found only in the San Francisco Bay Area and the Sacramento-San Joaquin River Delta. This native thistle grows in wet boggy habitats. Cirsium hydrophilum may reach 2 metres (6. 6 ft) in height with a branching, cobwebby stem. The leaves are longest near the base of the plant, approaching 90 centimetres (35 in) in length. They are cut into toothed lobes and covered in spines, particularly along the petiole. The inflorescence bears one or more flower heads, each up to 3 centimetres (1. 2 in) long. The head is lined with sticky, twisted, spiny phyllaries and contains pink to purple flowers. The fruit is an achene a 2-4 millimetres (0. 079-0. 157 in) long topped with a pappus of about 1. 5 centimetres (0. 59 in) centimeters. Varieties: There are two very localized varieties:The rare Cirsium hydrophilum var. hydrophilum, the Suisun thistle, is known from two occurrences in the Suisun Marsh, in the salt marsh habitat of the Delta in Solano County. It is treated as a federally listed endangered species. The very rare Cirsium hydrophilum var. vaseyi, Mt. Tamalpais thistle or Vasey's thistle, is known from about twenty occurrences on Mount Tamalpais in Marin County, in Vacaville, California in Solano County, and inside the Presidio in the City of San Francisco. It is currently not a listed federal or state endangered species.