Texas Invasives

Sign up for the iWire to get breaking news, event info and the species spotlight.

Go Back | Printer Friendly Fact Sheet

Federal Noxious Weed

TDA Noxious Weed

TPWD Prohibited Exotic Species

Invasive Plant Atlas of the US

NOTE:

means species is on that list.

Carduus tenuiflorus

Slender-flowered thistle

Synonym(s):
Family: Asteraceae
Duration and Habit: Annual Herb

Photographer: Joseph M. DiTomaso
Source: University of California - Davis

Description

Slenderflower or winged thistle is a winter annual broadleaf weed that is similar in appearance to Italian thistle, C. pycnocephalus. Plants grow up to 100 cm tall with triangular shaped stem wings that are up to one centimeter and tipped with a spine. The underside of leaves and stems are covered with cobwebby hairs. Terminal inflorescences can contain from 5 to 15 small pinkish corollas. First flower buds have been observed as close as 4 to 6 inches from the rosette.

Native Lookalikes: Currently no information available here yet, or there are no native Texas species that could be confused with Slender-flowered thistle.

Ecological Threat: Has a tendency to form dense stands and is an aggressive annual which can interfere and displace native prairie grasses.

Biology & Spread: Flowers in early spring through summer (Apr-July). Seed is readily spread by the wind and is also dispersed by hay cutting and bailing operations. Likely to be seen in disturbed areas, roadsides, overgrazed pastures and utility right of ways.

History: Introduced to California, Oregon and the Pacific NW from Southern Europe (Mediterranean region. Unknown in North Central Texas until ~1990.

U.S. Habitat: Usually associated with pastures, disturbed areas, and vacant lots. Often invading native prairies.

Distribution

U.S. Nativity: Introduced

Native Origin: Southern Europe

U.S. Present: CA, NJ, OR, PA, TX, WA

Distribution in Texas: North and Central Texas

Mapping

Invaders of Texas Map: Carduus tenuiflorus
EDDMapS: Carduus tenuiflorus
USDA Plants Texas County Map: Carduus tenuiflorus

Native Alternatives

Management

Mechanical removal is known to be effective if done prior to seed dispersal but must be repeated for 3-5 years to exhaust the seed bank. Thistle is also responds to very dilute chemical treatments containing 2-4-D (personal communication with Curt Decker, Resource Conservation Biologist, Fossil Rim Wildlife Ranch).

USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS. MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.

Text References

Shinners and Mahler's Illustrated , Flora of North Central Texas, (G.Diggs, B. Lipscomp and R.J.O'kennon), BRIT Press 1999

Flora of North America @ www.efloras.org volumes 19,20 & 21 pages 91,94.

Gassmann, A. and L.T. Kok.2002. SLENDERFLOWER THISTLE (WINGED SLENDER OR SEASIDE THISTLE). in Biological Control of Invasive Plants in the Eastern United States. USDA Natural Resources Conservation Service website www.nrcs.usda.gov.