Polymerissa

Polymerissa is a genus of flowering plants in the family Asteraceae, native to South America. The genus is characterized by its small, annual herbs, which typically grow to a height of 10-30 centimeters. The leaves are alternate, simple, and often have a hairy texture. The inflorescences are composed of one to several flower heads, each containing 20-40 disc florets and no ray florets. The disc florets are yellow and have five lobes. The fruit is a cypsela, which is a dry, one-seeded fruit with a pappus for dispersal.

Polymerissa is named after the Greek word "poly," meaning many, and "meris," meaning part, referring to the many-parted disc florets. The genus was first described by the German botanist Carl Friedrich Philipp von Martius in 1840. There are currently four recognized species in the genus Polymerissa, including Polymerissa acaulis, Polymerissa aculeata, Polymerissa corymbosa, and Polymerissa involucrata.

Polymerissa species are often found in open habitats such as grasslands, rocky outcrops, and disturbed areas. They are known for their rapid growth and ability to colonize disturbed sites. The plants are often used in restoration efforts to stabilize soil and prevent erosion. Polymerissa species are not typically cultivated as ornamentals, but they can be grown in gardens for their attractive flowers and low maintenance requirements.