SKELETONLEAF BURSAGE, Ambrosia
tomentosa Nutt. 1, top of plant; 2, root system and
young plant; 3, male flowers; 4, seed. Perennial,
reproducing by seeds and deep creeping rhizomes. Stems bushy, branched,
usually 1 to 2 feet (30 to 60 cm) tall. Leaves alternate, divided
into narrow lobes, hairy on underside, 2 to 5 inches (5 to 12.5 cm) long.
Flowers small, male and female borne separately but on the same
plant. Male flowers in small drooping heads along tips of branches; female
in axils of upper leaves. Burs surrounding female flowers bear 1 to 3 seeds,
have sharp spines when mature. Found in moist cultivated fields,
waste places, pastures, and irrigated areas, especially if poorly drained.
WOOLLYLEAF BURSAGE, Ambrosia grayi (A.,
Nels.) Shinners. A species closely related to the above. Leaves
covered with short woolly hairs on both surfaces, terminal lobe quite large.
Bur has curved rather than straight spines.