rhinanthus

from The Century Dictionary.

• noun A genus of gamopetalous plants of the order Scrophularineæ and tribe Euphrasieæ. It is characterized by a long two-lipped corolla, the upper lip entire, straight, compressed, and helmet-like; by a swollen and compressed four-toothed calyx, inflated in fruit; by four unequal stamens with equal anther-cells; and by a roundish capsule containing few winged seeds. The 2 or 3 very variable species are natives of temperate and northern regions in Europe, Asia, and America. They are annual erect herbs, more or less parasitic on the roots of grasses. They bear opposite crenate leaves, and yellow, violet, or bluish flowers sessile in the axils of deep-cut floral leaves, the upper flowers condensed into a spike. R. Crista-galli of the northern Old World is the common rattle, yellow rattle, or rattlebox of Great Britain: also called penny-grass and cockscomb. It is often injurious to herbage on account of its parasitic habit.