Family, Composite. Leaves, much cut and thin, opposite and alternate.
This unwelcome weed, when examined under the microscope, shows the fertile and sterile flowers in different heads on the same plant. The spikes of flowers above are staminate. Below, in the leaf-axils, are 3 pistillate flowers. Often the plant exhales rather a disagreeable odor. Its pollen is said to produce hay-fever. It has a strong, spreading root.
Mr. W. H. Gibson has found something curious and likable in this ugly weed. He says: "The pith obtained from the stem is lighter and more buoyant than any vegetable tissue of like bulk. It seems almost to float as it falls from your hand, while its cross-fracture, with its iridescent sheen, certainly brings reminders of the rainbow in the realms of the gods." Dr. Gray says the generic name Ambrosia "is ill-chosen for these worthless and coarse weeds."
Mr. Burroughs says: "Ambrosia, 'food for the gods'! It must be food for the gods, if anything, for, as far as I have observed, nothing terrestrial eats it, not even a billy-goat."