Isocarpha oppositifolia

Isocarpha oppositifolia, the Rio Grande pearlhead,^[2] is a New World species of plants in the family Asteraceae. It is widely distributed in eastern and southern Mexico, Central America, the West Indies (Cuba, Jamaica, Bahamas, Caymans, Trinidad), and northern South America (Colombia, Venezuela). The range extends northward, just barely crossing to the north side of the Río Grande in the two southernmost counties in Texas (Cameron + Hidalgo).^[3][4]

Isocarpha oppositifolia
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Asterales
Family:	Asteraceae
Genus:	Isocarpha
Species:	I. oppositifolia
Binomial name
Isocarpha oppositifolia (L.) Cass. 1822, conserved name not R.Br. 1817
Synonyms[1]
Synonymy Calea oppositifolia (L.) L. Dunantia achyranthes DC. Isocarpha angustata Griseb. Isocarpha atriplicifolia subsp. glabrata (S.F.Blake) Borhidi Isocarpha glabrata S.F.Blake Isocarpha oppositifolia (L.) R.Br. Isocarpha tricephala Cass. Santolina oppositifolia L. 1759

Isocarpha oppositifolia is an herb or subshrub up to 150 cm (4.9 ft) tall. Leaves are up to 15 cm (5.9 in) long, usually narrow but sometimes egg-shaped. One plant produces several flower heads, each a long flower stalk, each head with 60-150 disc flowers but no ray flowers.^[4]