Cirsium neomexicanum, New Mexico Thistle
Scientific Name: Cirsium neomexicanum
Common Name: New Mexico Thistle
Also Called: Desert Thistle, Foss Thistle, Lavender Thistle, Utah Thistle (Spanish: Cardo Santo)
Family: Asteraceae, Sunflower Family
Synonyms: (Carduus inamoenus, Cirsium arcuum, Cirsium neomexicanum var. neomexicanum, Cirsium neomexicanum var. utahense, Carduus nevadensis, Cirsium humboldtense, Cirsium utahense, Cirsium wallowense)
Duration: Biennial or short lived perennial.
Size: 6 feet or more.
Growth Form: Forb/herb; erect, main stem, some branching above, spotted with cobweb like patches of short soft hairs; all parts with long stiff sharp spines.
Leaves: Green or greenish-gray; highly variable along stems; basal rosettes, upper oblong-elliptic to oblanceolate, deeply pinnatifid, uppermost leaves shorter, wing like bracts; spiny throughout.
Flower Color: Pink or purple, lavender or white; disk flowers only, large showy flower heads 2 or 3 inches wide, surrounded by sharp spine tipped bracts or phyllaries; solitary or 2 or 3 flower heads on tips of peduncles, loose corymb-like arrays.
Flowering Season: March to September, successful blooms following winter and spring rains and again after heavy summer monsoon rainfall.
Elevation: 1,000 to 6,500 feet.
Habitat Preferences: Plains, mesas, rocky hillsides, foothills, roadsides and washes.
Recorded Range: In the United States in AZ, CA, CO, NM, NV and UT and in northwest Mexico. New Mexico Thistle is scattered throughout most of Arizona.
North America & US County Distribution Map for Cirsium neomexicanum.
U.S. Weed Information: No data available.
Invasive/Noxious Weed Information: In North America the genus Cirsium is listed as a Noxious Weed by the States of Arkansas and Iowa. Plants included here are invasive or noxious.
Wetland Indicator: No data available.
Threatened/Endangered Information: No data available
In the Southwestern United States: Arizona has 19 species of Cirsium, California has 26 species, Nevada has 16 species, New Mexico has 19 species, Texas has 12 species, Utah has 23 species. All data is approximate and subject to taxonomic changes.
Comments: New Mexico Thistle is not an aggressive noxious weed however the genus Cirsium is often included in many weed lists presumably through its relationship to aggressive thistles such as the European invasive Bull Thistle, Cirsium vulgare. It attracts many different insects including bees, wasps and butterflies. A southwestern species, the geographic range of New Mexico Thistle suggests it to be a Mojave Desert species although it is native to and common in both the Mojave and Sonoran Deserts.
For a comprehensive thoroughly documented review of New Mexico Thistle see the USDA USFS Fire Effects Information System, or FEIS.
Cirsium neomexicanum flowers is attractive to many native bees (nectar and pollen) and insects. The Xerces Society for Invertebrate Conservation acknowledges in their 2017 publication "Native Thistles: A Conservation Practitioner's Guide" that "native thistles are misunderstood and wrongly maligned group of wildflowers..." when in fact native thistles provide resources for many species of bees, butterflies and other wildlife which rely heavily on these species plants. "Monarch butterflies visit native thistle flowers more than any other wildflowers in some regions during their migration back to Mexico".
Seeds from New Mexico Thistle (and other thistles) have been found to be one of the favorite foods of goldfinches and many other birds.
The genus Cirsium is from the Greek word "kirsion" "a kind of a thistle" which is translated from the Greek word "kirsos" meaning "swollen vein or welt"; a reference to their remedy against swollen veins and welts as thistles were quite often used as a remedy for these types of ailments.
The species epithet neomexicanum is a direct reference meaning of or from or otherwise honoring New Mexico.
New Mexico Thistle has been used for medicinal purposes by Navajo and Yavapai Indians.
See species account from Native American Ethnobotany, University of Michigan, Dearborn.