Overview
Cirsium wrightii (Wright’s marsh thistle; Grey) was described by Asa Gray in the Smithsonian Contributions to Knowledge Vol. V (Gray 1853), and by Coulter (1891). Cirsium wrightii is a member of the Asteraceae (sunflower) family, produces a 3- to 8-foot (ft.) (0.9- to 2.4-meter (m)) single stalk covered with succulent leaves. Depending on environmental conditions, it can exhibit life history characteristics of a biennial plant (a plant completing development in 2 years, and producing flowers in its second year) or a weak monocarpic perennial (a plant that lives two or more years, then flowers, sets seed, and dies). The species occurs in wet, alkaline soils in spring seeps and marshy edges of streams and ponds between 3,450 and 7,850 ft. (1,150 and 2,390 m) in elevation.
Historically found in Arizona, New Mexico, Texas, and Mexico, C. wrightii has been a candidate for listing under the Endangered Species Act of 1973, as amended (Act), since 2010 (75 FR 67925). The State of New Mexico lists C. wrightii as endangered under the New Mexico Endangered Plant Species Act (9-10-10 NMSA). Cirsium wrightii occurs in some of the same New Mexican cienegas occupied by the federally threatened Helianthus paradoxus (Pecos sunflower).
Scientific Name
Identification Numbers
Characteristics
Habitat
Cirsium wrightii is a wetland thistle that occurs in wet meadows associated with alkaline springs and seeps (cienegas). Cirsium wrightii was historically known to occur in Arizona and New Mexico in the United States, and Chihuahua and Sonora in Mexico (Sivinski 2012).
Land on which the natural dominant plant forms are grasses and forbs.
A dense growth of trees and underbrush covering a large tract.
A landmass that projects conspicuously above its surroundings and is higher than a hill.
A natural body of running water.
Of or relating to cities and the people who live in them.
Environments influenced by humans in a less substantial way than cities. This can include agriculture, silvaculture, aquaculture, etc.
Areas such as marshes or swamps that are covered often intermittently with shallow water or have soil saturated with moisture.
Areas where ground water meets the surface.
Physical Characteristics
Cirsium wrightii is distinctive among southwestern thistles. It is characterized by its tall (3- to 8-foot (ft.) (0.9- to 2.4-meter (m)), erect growth form which has a single central stalk that is densely covered with succulent leaves which are strongly decurrent (with bases of leaves extending down the stem as two wings). The plant is prickly with short black spines and has short taproots with many slender fibrous lateral roots (Sivinski 1996a, Arizona Game and Fish Department 2001). Numerous slender flowering branches emerge at broad angles from the stalk, starting about one-third up the length of the plant. The flowering branches at the top of the plant are the longest. Each branch is terminated by one or a few small flowering heads, which have numerous slender phyllaries (small bracts forming the flower head of a composite plant) (Sivinski 1996a). Flowering occurs August to October (Sivinski 1996a). Flowers are white to pale pink in areas of the Sacramento Mountains of New Mexico, but are vivid pink in the Pecos Valley (Sivinski 1996b).
Life Cycle
Depending on environmental conditions, Cirsium wrightii can display life history traits of a biennial (a plant completing development in 2 years, flowering in its second year) or a weak monocarpic perennial (a plant that flowers, sets seed, and then dies). Cross pollination is achieved by insect pollinators, primarily bees. Like other species in the genus Cirsium, C. wrightii produces numerous seeds per flowering plant. After germination, seedlings develop into an intermediate rosette form for most of a year or longer before bolting (producing a stem) and growing into the mature, flowering plant. It does not reproduce vegetatively (asexually from parent plant).
Depending on environmental conditions, Cirsium wrightii can display life history traits of a biennial (a plant completing development in 2 years, flowering in its second year) or a weak monocarpic perennial (a plant that flowers, sets seed, and then dies). Cross pollination is achieved by insect pollinators, primarily bees. Like other species in the genus Cirsium, C. wrightii produces numerous seeds per flowering plant. After germination, seedlings develop into an intermediate rosette form for most of a year or longer before bolting (producing a stem) and growing into the mature, flowering plant. It does not reproduce vegetatively (asexually from parent plant).
Similar Species
Cirsium wrightii keys close to two nonnative plants, C. arvense and C. palustre (Baker 2011). In the field, C. wrightii may be easily distinguished from the other two species by its tall stature; large, somewhat succulent, nearly glabrous (smooth surface) basal leaves; small heads; and green phyllaries with glutinous (sticky) ridges and very small terminal spines (at the ends of phyllaries; i.e., composite flower heads) (Baker 2011).
Geography
Cirsium wrightii is a wetland thistle that occurs in wet meadows associated with alkaline springs and seeps (cienegas). Cirsium wrightii was historically known to occur in Arizona and New Mexico in the United States, and Chihuahua and Sonora in Mexico (Sivinski 2012). The single location in Arizona was a historical 1851 collection from San Bernardino Cienega, which straddles the international border with Mexico, and no longer has suitable wetland habitat on the Arizona side of the line (Baker 2011). Reports of Cirsium wrightii from Texas were common (Keil 2006, Sivinski 1996), but in subsequent examinations of Texas specimens purporting to be C. wrightii, the majority of specimens were found to be C. texanum or other Cirsium species (75 FR 67928). David Keil mentions seeing a specimen of C. wrightii from Texas, but did not recall in which herbarium the specimen is located (Keil 2011 in Sivinski 2012). In 2018, an herbarium specimen collected from Presidio County, TX in 2003, was re-examined and determined to be C. wrightii (Newsom 2018). Similarly, another herbarium specimen collected from Pecos County, TX, in 1849 was re-examined and determined to be C. wrightii.
In 2018, C. wrightii was rediscovered in Mexico in one of five surveyed locations (Sánchez Escalante et.al. 2019). Other possible Mexican locations of C. wrightii have not been specifically studied or surveyed, however, some of its United States populations are known to be extirpated or declining (Sivinski 2012). The only confirmed extant populations in the United States are in the New Mexican counties of Chaves, Eddy, Guadalupe, Otero and Socorro.
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