Description from Flora of China
Herbs, annual or perennial, hemiparasitic. Leaves opposite, lower ones usually small, increasing in size upward. Inflorescences terminal spikes or racemes; bracts larger than leaves, opposite, palmately veined, margin callous thickened dentate. Calyx tubular to campanulate, 4-lobed, more deeply parted medianly than laterally. Corolla tube tubular, apically inflated; limb 2-lipped; lower lip 3-lobed, lobe apices often emarginate; upper lip straight, galeate, lobes revolute. Stamens 4, didynamous, anthers connivent and enclosed by galea; locules parallel and free, pointed at base but posterior 2 anthers each with 1 locule spurred, all 4 with barbate hairs along slit. Stigma slightly dilated, entire or 2-lobed. Capsule compressed, 2-grooved, loculicidal, apex obtuse. Seeds numerous, small, ellipsoid, with cross striate wings.
About 200 species: cosmopolitan; 11 species in China, belonging to 2 disjunct sections.
The taxa in this genus often are hemiparasitic on grasses.
The Taiwan species of Euphrasia all belong to E. sect. Paradoxae Pugsley, which includes perennial taxa that also occur in tropical alpine mountains on SE Asian islands, New Guinea, New Zealand, and Juan Fernandez Island of Chile. All the other Chinese species of Euphrasia belong to E. sect. Semicalcaratae Bentham, which includes annual taxa that occur in the northern hemisphere temperate zones as well as alpine mountains in the northern subtropics.