Anthemis arvensis L.
CC = *
CW = 5
MOC = 12
Family - Asteraceae/Anthemideae
Habit - Taprooted annual forb.
Stems - Erect to ascending, to 50 cm, multiple from the base, branching, cobwebby pubescent (less so near base), green to red in strong sun.
Leaves - Alternate and basal (basal leaves sometimes withered by flowering time), sessile or short-petiolate with winged petioles and slightly broadened and more or less clasping bases. Leaf blades to 4 cm, deeply 1-3 times pinnately lobed, hairy and glandular, the ultimate segments mostly linear to threadlike, sharply pointed at the tip, mostly 1-veined. Foliage aromatic which bruised.
Inflorescence - Solitary, terminal, pedunculate flower heads.
Heads - Involucre 1.2 cm in diameter, 4-5 mm tall. Phyllaries in one or two series, slightly overlapping, to 5 mm long, 2 mm broad, scarious, with a green midvein, arachnoid pubescent externally, glabrous internally. Receptacle conical. Chaffy bracts present; these thin, translucent, 3 mm long, 0.4 mm broad, slightly folded, glabrous, acuminate, linear.
Ray flowers - Pistillate, fertile, 15 per head. Ligule white, 1.5 cm long, 5-6mm broad, glabrous, 2-3-notched at apex, oblong. Corolla tube to 2 mm long, greenish. Style bifurcate, exserted. Pappus none.
Disk flowers - Disk to 1.2 cm broad, becoming globose with age. Corolla -3 mm long, translucent at base, becoming yellow at apex, 5-lobed, expanded in apical 1/2. Lobes acute, to 0.6 mm long, recurved. Stamens 5, adnate at base of corolla tube constriction. Filaments very short. Anthers yellow, included, 1.1 mm long, connate around style. Style barely exserted beyond anthers, translucent-yellow. Stigmatic portion of style 0.5mm long. Pappus none.
Flowering - May - September.
Fruits - Achenes 1.7-2.2 mm long, the ribs smooth or slightly uneven, glabrous.
Habitat - Fields, roadsides, railroads.
Origin - Native to Europe.
Other info. - This species can be found in a few scattered locations in Missouri but is uncommon. It can be identified by its divided leaves and Chrysanthemum-like flower heads. It could be confused with plants in the Matricaria or Tripleurospermum genera, which can look similar. It can be differentiated from those by the presence of chaffy bracts within the flowering head, which the other genera lack.
Photographs taken in Brown Summit, NC., 5-17-02, and off Hwy 24, TN., 5-10-04.