San Pedro, CA
Eriogonum inflatum, the Desert Trumpet, is a perennial plant of the family Polygonaceae. The plant possesses very small yellow or pink flowers and an inflated stem just below branching segments. Eriogonum: from the Greek erion, "wool", and gonu, "joint or knee", in reference to the hairy or woolly joints of some of the species of the genus, but not particularly inflatum. It is found in the Mojave Desert and other deserts.
The swelling of the stems was assumed to have been influenced by the presence of gall insects, most notably of the genus Onyerus. The female wasp produces a small hole on the inflated portion of the Desert Trumpet, packs the cavity with larvae and lays her eggs upon them, providing a food source, and a protected environment for the offspring. Irritation caused by this process was said to have enlarged the cavity over time. Recently, research performed by a world authority on the genus Eriogonum, Dr. J. L. Reveal of the University of Maryland, College Park, revealed the swollen stem of Eriogonum inflatum is due to high concentrations of carbon dioxide in the solid stem and seems to be related to gas regulation.
Some insects utilize the swollen stem as a larder, but the inflation is not caused by the larval feeding of gall insects.
May 8th, 2012
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