Anthemis cotula L.

Stinking Chamomile, Dog Fennel

Anthemis_cotula_plant.jpg
STATS

Introduced
CC = *
CW = 3
MOC = 50

© SRTurner

Family - Asteraceae/Anthemideae

Habit - Taprooted annual forb, aromatic with an unpleasant odor. Foliage sparsely to densely pubescent with somewhat appressed, sometimes 2-branched hairs.

Stems - Ascending to erect, to 50 cm, finely ridged, usually branched above the midpoint.

Anthemis_cotula_stem1.jpg Stem and node.

© SRTurner

Anthemis_cotula_stem2.jpg Stem and leaves.

© SRTurner

Leaves - Basal and alternate, deeply lobed. Basal leaves often wilted at flowering time. Blades 1-6 cm long, oblanceolate to elliptic or ovate, deeply 2 or 3 times pinnately lobed, the basal lobes sometimes appearing fascicled, the ultimate segments linear, 0.5-4.0 mm long, sharply pointed, mostly 1-veined.

Anthemis_cotula_leaf1.jpg Leaf adaxial.

© SRTurner

Anthemis_cotula_leaf2.jpg Leaf abaxial.

© SRTurner

Inflorescences - Solitary heads at branch tips, the stalks 3-8 cm long at flowering.

Heads - Radiate. Involucre cup-shaped to hemispheric, 2.5-5.0 mm long, the bracts more or less in 2 or 3 loosely overlapping series, the outer ones somewhat shorter, elliptic-lanceolate to narrowly oblong or narrowly ovate-triangular, rounded to bluntly pointed at the tip, sparsely to moderately hairy, tan to brown, often with a narrow, green or brown midvein, the midrib not keeled, the margins broad, thin and papery, somewhat irregular to unevenly fringed. Receptacle hemispheric at flowering, elongating to conical or cylindrical at fruiting, solid, with chaffy bracts confined to the central portion.

Anthemis_cotula_head1.jpg Flowering head.

© SRTurner

Anthemis_cotula_receptacle.jpg Sectioned head, showing receptacle. Tips of chaffy bracts are visible as small green projections above the disk florets.

© SRTurner

Anthemis_cotula_involucre.jpg Involucre.

© SRTurner

Anthemis_cotula_head2.jpg Young head.

© SRTurner

Flowers - Ray florets 10-20, sterile, the corolla white, 5-9 mm long, sometimes inconspicuously glandular. Disc florets perfect, numerous, the corollas yellow, 1.5-3.0 mm long, the 5 lobes often minutely glandular. Pappus absent or a very short collar.

Anthemis_cotula_florets.jpg Disk and ray florets. Styles are sometimes visible in the ray florets, but these are undivided and nonfunctional.

The tips of the chaffy bracts are visible in this view as tiny green projections among the central disk florets.

© SRTurner

Fruits - Achenes 1-2 mm long, the ribs appearing strongly cross-wrinkled or tubercled, often also with glands between the ribs.

Flowering - May - October.

Habitat - Forest openings, streambanks, fields, orchards, barnyards, ditches, railroads, roadsides, open, disturbed areas.

Origin - Native to Europe.

Lookalikes - Anthemis arvensis, Matricaria chamomilla, Tripleurospermum inodorum.

Other info. - This small daisy-like plant is found in scattered localities throughout much of Missouri and much of the continental U.S., though it is rare or absent in much of the Plains and (Rocky) Mountain areas. It is recognized by its small, daisy-like flowering heads and highly dissected foliage which emits a foul odor when bruised. This latter trait is probably the fastest means of differentiating the plant from its lookalikes, which it strongly resembles. More technical characters include the solid, conical receptacle, sterile ray florets, and presence of narrow, awl-like chaffy bracts toward the center of the head.

This species is not particularly common in Missouri. Its prevalence in barnyards and pastures suggest that it may be spread as a contaminant in hay.

Photographs taken at the Whiskey Creek sheep farm, near Krakow, Franklin County, MO, 6-16-2021 (SRTurner).