Spermacoce ovalifolia

Spermacoce ovalifolia, the broadleaf false buttonweed, is a species of plants in the Rubiaceae. It is native to Mexico, Central America, parts of the Caribbean (Cuba, Puerto Rico, Haiti, Trinidad, and the Windward Islands), and South America (Venezuela, Colombia, Ecuador, Peru, Bolivia, Brazil, Paraguay).
"Spermacoce ovalifolia" is an annual herb about 30 cm tall. Leaves are ovate, up to 4 cm long. flowers are very small, in dense axillary clusters.