Weak-leaf Bur Ragweed
Ambrosia confertiflora
Photographed along Rackensack Wash near Camp Creek, Maricopa Co., Arizona, Oct 2009.
PERENNIAL HERB: Regrows from underground rhizomes which spread out thus
forming colonies of this plant. Mostly less than ½ meter
tall
LEAVES: Leaves are twice, or more, pinnately disected into narrow
segments.
RANGE: In the Sonoran Desert found in canyons, near riparian habitats,
in mesquite bosque openings, mostly at the higher elevations. Common also in
high desert habitats such as juniper woodlands, chaparral and grasslands.
Widely distributed from California east into south-central USA.
FLOWERS: Flowering may occur in late spring and again in late summer and
fall depending on rainfall. The greenish flowers are not showy, but the copious
pollen dispersed by the wind is responsible for hayfever symptoms in many
people. On the spikes female flower heads are below the smaller exclusively
male-flowered heads above.
FRUIT: The seeds are enclosed in a weak bur.
UNARMED. No thorns, burs have weak barbs.