Species - Ragweed
Spring - Fall
Ambrosia is an annual and perennial weed and tree. Species can only grow a few inches long or more than four feet tall. The stems are erect, recumbent or drooping and many grow from rhizomes. The leaves can be alternately, opposite or both arranged. The leaves have many shapes, sometimes pinnately or palmately divided into lobes. The sides are smooth or serrated. Some are hairy and mostly glandular. Ambrosia is monoecious, usually forming inflorescences with both stalk and pistil flowers. The inflorescences are usually in the form of a spike or grape usually consisting of stamina flowers with several pistil clusters around the base. Staminate flowers have stamens surrounded by white or purple flowers. Pistillate flowers have fertile eggs surrounded by numerous phyllaries and smaller, smaller flowers. Instead of the wind, the flowers grow and the fruits develop. They are burrs, sometimes decorated with backs, wings or thorns. Many Ambrosia species occur in desert and semi-desert areas, and many ruderal species grow in habitat types.
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Image from Wikipedia