Shrubby false buttonweed

Spermacoce verticillata, shrubby false buttonweed, is an erect to ascending perennial herb or subshrub in the Rubiaceae native to tropical South America and the Caribbean, now widely naturalised across the tropics of Africa, Asia, and the Pacific. It grows 30-90 cm tall from a woody base, with quadrangular, finely puberulent stems that branch from the lower nodes. The narrowly lanceolate to elliptic leaves are opposite, 2-8 cm long, with strongly developed lateral veins, scabrid surfaces, and interpetiolar stipules fringed with several bristly lobes characteristic of the family. Small, white, four-lobed, salverform flowers about 3-4 mm across are produced in dense, globular, axillary whorls clustered at the upper nodes, giving the inflorescence the appearance of a pincushion. The fruits are tiny, two-seeded capsules. The species thrives on roadsides, sandy waste ground, and pastures, and is regarded as a weed in many parts of its introduced range.