Herbage with vile odor. Leaf blades mostly obovate, 20-35 mm, ultimate lobes linear to spatulate or oblanceolate, 0.5-1 mm wide, sparsely puberulent or strigillose, minutely gland-dotted (in pits). Heads borne singly or 2-4 in corymbiform arrays. Peduncles 1-2(-8) cm, ebracteate. Involucres 3-3.5 × 4-6 mm. Receptacles ± conic to subspheric, muricate. Disc corollas 1.5-2 mm. Cypselae slightly curved, 0.6-0.8 mm, sparingly dotted with minute, glistening oil glands; pappi coroniform, 0.05-0.1 mm, margins subentire or minutely dentate. 2n = 12.
Flowering Mar-Jun. Disturbed sites, coastal scrub; 500-900 m; introduced; Ariz., Calif.; South Africa.
FNA 2006, Jepson 2012
Duration: Annual Nativity: Non-Native Lifeform: Forb/Herb General: Herbaceous annuals, to 50 cm tall, stems 1-5 or more from bases, erect to ascending, branching from the base or throughout, puberulent to sparsely covered with stiff, slender bristles (strigillose), glabrous to gland dotted (in pits), herbage strongly scented with a vile odor. Leaves: Small, alternate, mostly obovate, 1-4 cm long or more, 2-3-pinnately dissected with linear segments 20-35 mm long, ultimate lobes linear to spatulate or oblanceolate, 0.5-1 mm wide, sparsely puberulent or minutely strigose (with minute, stiff hairs), dotted minute resin glands. Flowers: Yellow and showy in globose, discoid heads, ill-smelling, disc flowers generally 100-250 or more, corollas tubular, 4-lobed, 1.5-2 mm long, receptacles conic to subspheric, muricate, involucres 3-3.5 mm long and 4-6 mm diameter, anthers minute, with lanceolate tips and rounded or cordate bases, styles short with truncate branches and bushy tips, heads also bushy, borne singly or 2-4 in corymbiform arrays on bractless peduncles 1-8 cm long. Fruits: Cypselae (achenes) cylindric or 4-angled and ribbed, faces resin-gland-dotted, 0.5-1 mm long, slightly curved, sparingly dotted with minute, glistening oil glands. Pappi minute, in a narrow crown, 0.05-0.1 mm long with subentire or minutely dentate margin Ecology: Found on roadsides, river bottoms, waste ground and disturbed areas from 1,500-3,000 ft (457-914 m); flowers February-June. Distribution: Arizona, California; South Africa. Notes: The showy, yellow and spherical discoid heads and small pinnatifid leaves of this species standout in arid environments. Nicknamed pineapple weed for the smell. The recent systematics of this plant give a realignment with Oncosiphon for the nomenclature for this species. This is a potentially nasty invasive plant, it is spreading via southern California. Ethnobotany: Prolific uses as medicinal, from gynecological aid to antidiarrheal, to cold remedy, to heart medicine, to use as food. Synonyms: Cotula pilulifera, Matricaria globifera, Pentzia globifera, Matricaria discoidea Editor: LCrumbacher 2012 Etymology: Oncosiphon comes from the Greek onkos, "bulb, mass," and siphon, "tube," alluding to the tube of the corolla, while piluliferum means bearing little balls or globules, in this case referring to the globular flowering heads.