Common Ragweed

Common Ragweed
Common Ragweed. Ambrosia artimisiifolia.
Asteraceae, the daisy, sunflower or composite family.

Plant: Course, usually much branched plant 1'-5', often hairy, with dissected leaves and many erect, elongated clusters of small green flowers. Annual.
Flowers: Green, tiny, with no apparent petals. Two types. Male (staminate) flowers in long spike-like clusters up to 6" long, Typically many per plant. Individual florets resemble downturned cups on short stems containing bunches of stamens. Female (pistillate) flowers are inconspicuous, and occur singly or in small groups in the leaf axils.
Leaves: Usually alternate, highly dissected, pinnately or bipinnately lobed, to 4" long.
Fruit: Small, seedlike.
Blooming: August-October
Habitat: Waste areas, fields, roadsides.

Comments: Ragweed is highly variable in appearance, with several recognized varieties. A common weed, the plant is wind-pollinated, consistent with the inconspicuous flowers. The pollen is a primary cause of hay fever. Given this, the genus name (ambrosia, nectar of the gods) seems a bit incongruous. The seeds are an important winter food source for some birds.

Where to find it: Mostly along the roads and lawn boundaries.