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Tucson Bur Ragweed

Ambrosia cordifolia

photo © by Michael Plagens

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.

Asteraceae -- Sunflower Family

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Copyright Michael J. Plagens, 1999-2009