Habit: Spermacoce tenuior grows as an annual up to 50 cm in height. The leaves are arranged oppositely with stipules between the petioles. The leaves are linear to oblong lanceolate up to 5 cm long (typically shorter), with an acute leaf apex and an entire margin.
The complete, perfect, actinomorphic flowers occur in heads in leaf axils. A stipular sheath subtends the flowering “head”. The calyx has 4 unfused, pubescent, sepals. The corolla has 4 fused white petals that form a short tube with a pubescent throat. There are 4 stamens that are fused to the perianth forming a hypanthium. The ovary is inferior with 2 locules with few ovules. The fruit is a bivalved pubescent capsule at maturity.
Habitat: Spermacoce tenuior grows in open areas in Human Altered environments (yards, roadsides, disturbed areas).
Distribution: Spermacoce tenuior occurs throughout the Lucayan Archipelago, the Caribbean region, North America and all tropical and subtropical regions of the world.
Medicinal/Cultural/Economic usage: Spermacoce tenuior is not known to be used medicinally in the Lucayan Archipelago.