WESTERN RAGWEED, Ambrosia psilostachya DC. 1, male flowers on spike; 2, female flowers; 3, seed; 4, entire plant. Perennial, reproducing by rootstocks and seeds. Stem erect, normally less than 20 inches (50 cm) tall, hairy, bushy, branched above, often growing in dense patches. Leaves with short petioles, alternate or opposite, ovate-lanceolate, with very deep lobes, sometimes compound, rough. Flowers of two kinds. Male flowers in clusters on ends of stems and branches; female flowers few, without petals, in axils of upper leaves. Seed about 1/8 inch (3 mm) long, with a woody hull that has a pointed tip surrounded by short spines. Found in prairies, plains, and uncultivated areas. The pollen is a hazard to hay fever sufferers. Also known as perennial ragweed.