Laennecia coulteri (A. Gray) G.L. Nesom

Coulter's Horseweed
Asteraceae (Sunflower Family)


Coulter's horseweed is an erect, glandular-pubescent annual with densely soft-hairy herbage and a simple stem paniculately branched above growing to some 40" tall.  The leaves are narrowly oblong from 3/4" to 3" long, coarsely toothed or shallowly spreading-lobed, the lowest leaves petioled and the upper cauline sessile and ± clasping, villous or hirsute.  The numerous small heads are on peduncles to 3/8" long. The involucres are approximately 1/8" high and slightly more than that in diameter, and have phyllaries that are linear-attentuate and densely glandular with green mid-veins. There are as many as 125-250 ray flowers without ligules and 5-15 disk flowers with soft whitish pappi. Coulter's horseweed occupies generally disturbed places below 3000', occasionally in most flats in coastal sage scrub, particularly in the Imperial Valley and Channel Islands, blooming from May to October.

Click here for Latin name derivations: 1) Laennecia 2) coulteri.
Pronunciation: lee-NEE-see-a KOLE-ter-eye.
Formerly Conyza coulteri.
Click here for Botanical Term Meanings.