Laennecia coulteri (A. Gray) G.L. Nesom  
Family: Asteraceae
Coulter's horseweed,  more...
[Conyza coulteri A. Gray,  more]
Laennecia coulteri image
Max Licher  
Annuals, 10-150 cm. Leaf blades: bases ± clasping, faces usually both hirtellous to villous and ± gland-ular-viscid; proximal broadly spatulate to oblong, 20-50 × 10-20 mm, obscurely lobed or coarsely toothed; distal oblong to elliptic, 10-20 × 3-10 mm, coarsely toothed from near bases or entire. Heads in racemiform-paniculiform arrays. Involucres 2.5-3+ mm. Receptacles 2-3 mm diam. Pistillate florets 60-100+; corollas: lengths ± 1 / 2 styles, laminae 0. Disc florets 5-20. Cypselae pale tan, 0.5-1 mm, glabrous or sparsely strigillose (hairs 0.05-0.1 mm), sometimes stipitate- or sessile-glandular; pappi fragile or readily falling, of 10-30 whitish bristles in 1 series, (2.5-)3.5-4 mm. 2n = 18. Flowering year round, mostly fall. Stream banks, roadsides, other disturbed sites, clays or sands, often alkaline soils; -60-1800 m; Ariz., Calif., Colo., Nev., N.Mex., Tex., Utah; Mexico. J. M. Kingsbury (1964) reported Laënnecia coulteri (as Conyza coulteri) to be toxic to livestock.

Plant: Taprooted annual forb to 1 m; herbage sticky glandular Leaves: Taprooted annual forb to 1 m; herbage sticky glandular; leaves mostly alternate, clasping, oblong-lanceolate, 2-15 mm wide, regularly toothed or shallowly lobed Flowers: inflorescence many-flowered elongate panicles; flower heads ~3mm across, discoid; pistillate flowers filiform, in several series along outside of head; hermaphrodite flowers yellow toward center of head; pappus of white capillary bristles. Notes: stems striate References: Veg. & Flora of the Sonoran Desert, ASU specimens
Laennecia coulteri image
Max Licher  
Laennecia coulteri image
Max Licher  
Laennecia coulteri image
Max Licher  
Laennecia coulteri image
Max Licher  
More Images        Web Links       View Parent Taxon       Close window