About Isocarpha oppositifolia (L.) Cass.
Isocarpha oppositifolia, commonly called the Rio Grande pearlhead, is a New World plant species belonging to the Asteraceae family. It has a wide distribution across eastern and southern Mexico, Central America, the West Indies including Cuba, Jamaica, the Bahamas, the Cayman Islands, and Trinidad, and northern South America including Colombia and Venezuela. Its range extends northward, barely crossing to the north side of the Río Grande into the two southernmost counties of Texas: Cameron and Hidalgo. This species grows as an herb or subshrub reaching up to 150 cm (4.9 ft) in height. Its leaves can grow up to 15 cm (5.9 in) long, and are usually narrow though they may sometimes be egg-shaped. A single plant produces multiple flower heads, each borne on a long flower stalk. Each flower head holds 60 to 150 disc flowers and has no ray flowers.
