Tucson Bur Ragweed
Ambrosia cordifolia
Photographed in Pima Canyon, Sta. Catalina Mts., Pima Co., Arizona. April 22, 2009.
SHRUB : Weakly woody shrub up to 1½ meters
tall. Tends to form small thickets.
LEAVES: Leaves are broadly heart-shaped with coarsely toothed margins.
RANGE: In the Sonoran Desert canyons near Tucson, Arizona. Less common
towards southwest. Absent in deserts near Phoenix.
FRUIT: The seeds are enclosed in a bur.
FLOWERS: Feb. to March. These are composite flowers with male and female
flowers in separate heads on the same plant. The terminal spikes have several
heads of only female flowers below and a larger number of exclusively
male-flowered heads above. The petals are vestigial yet the male flowers appear
yellow because of the copious pollen.
Anemophilous pollination means that during the spring blooming period
allergy patients will sufferer and most everyone else will at least notice the
abundant grit in the eyes.
UNARMED. No thorns.