May 31, 2023

The good, the bad and the endangered: New Mexico’s thistles are more than just weeds

Lincoln National Forest Botanist Phillip Hughes points to a meadow where Wright's Thistle has been known to grow.

Nicole Maxwell/New Mexico Political Report

Lincoln National Forest Botanist Phillip Hughes points to a meadow where Wright's Thistle has been known to grow.

In a meadow near Silver Lake in the Sacramento Mountains, one can look out onto a small patch of habitat containing several species of plant and animal life 

Although spring is too early to see many of the species of plant life, such as a few species of thistles which do not bloom until late summer, other plant and animal species are already present, including the New Mexico Meadow Jumping Mouse, Sacramento Mountain Butterfly, the Mexican Spotted Owl along with invasive species like the Musk Thistle.

“It’s an island,” District Biologist for the Sacramento Ranger District Philip Hughes said, referring to the species of plants and animals that are endemic to the Sacramento Mountains. Endemic means these species live in a specific geographical area and do not grow naturally elsewhere.

Recently, the Wright’s marsh thistle was listed as threatened. This thistle is native to marshlands in New Mexico, such as those seen in the meadow near Silver Lake and in a preserve in Santa Rosa, Bitter Lakes National Wildlife Refuge in Roswell and in the Rio Grande Valley.

There are 12 native species of thistles in New Mexico, state Botanist Erika Rowe told NM Political Report.

“We have some property in Santa Rosa… associated with the ciénega springs,” Rowe said. “There are these sort of natural seepage kind of meadows this kind of habitat (Wright’s Thistle) really prefers, they’re kind of alkaline seepage meadows that are very unique and kind of have a constant flow of water through the system.”

More: Flower found in marshes of southern New Mexico listed as threatened

The New Mexico Native Plant Society released a New Mexico Thistle Identification Guide in 2016 to help distinguish between native thistle species and non-native invasive noxious species such as the creeping thistle, bull thistle, Scotch thistle and the musk thistle.

“Creeping thistle is the most problematic and pernicious non-native thistle in New Mexico,” according to the guide. “Patches of stems from root sprouts can become huge and dense to the exclusion of native wetland vegetation. It is damaging to riparian and wetland ecosystems at springs, wet mountain meadows and the margins of ponds and creeks.”

The bull thistle is a 3-5 foot tall biennial mostly seen along roadsides in 4,500-9,800 feet elevations and can be controlled by hand digging.

The Scotch thistle is a large attractive plant native to Scotland that is not a welcome plant in New Mexico. The national emblem of Scotland, it came to New Mexico sometime in the 1980s and can be found in “disturbed soils in riparian areas and through grasslands, piñon-juniper woodlands, ponderosa pine forests (and) 4,000-7,600 feet elevation,” the guide states. It can be identified by its gray filamented stems and spiny wing-like leaves going down the stems and purple flowers.

Then there is the musk thistle with its large purple flower that grows in large amounts on disturbed soils such as roadsides, urban development, fallow farm fields and grazed mountain pastures, the guide states. Every once in a while, musk thistles grow naturally in undisturbed habitats.

In an effort to control musk thistle growth, the seedhead weevil was introduced to New Mexico but has, so far not been effective in higher elevations due to the thistle’s late bloom and has been attacking some native thistles, according to the guide.

The musk thistle looks strikingly similar to the endangered Sacramento Mountains Thistle.

Aside from the invasive thistle species, there are two endangered species of thistle including the Sacramento Mountains Thistle which is only known to grow in the Sacramentos and the recently listed threatened Wright’s Thistle.

The guide says the Sacramento Mountains Thistle is one of the native thistles the seedhead weevil has been destroying. Similar to the musk thistle, it has a purple flower but is not as prolific as the musk thistle. The Sacramento Mountains Thistle is threatened due to insect predators, grazing and aquifer depletion.

Wright’s Thistle has a white or light purplish-pink flower with semi-succulent or leathery leaves, the guide states.

Other species of thistle that grow naturally in New Mexico and are not endangered include the Arizona Thistle which is native to the western half of New Mexico and can be found in rocky slopes and canyons in higher elevations; the Alpine Thistle which is endemic to the Sangre de Cristo Mountains in northern New Mexico; Graham’s Thistle which is very rare and has only been found in southern Catron County and New Mexico Thistle which flowers in late spring instead of late summer as most thistles do and can be found in most of New Mexico.