Images: ©Jouko Lehmuskallio
Narrow-leaved Rattle
Rhinanthus serotinus
- Family: Figwort Family – Scrophulariaceae
- Growing form: Annual herb. Semiparasite.
- Height: 30–50 cm (12–20 in.). Stem much-branched, with short red stripes, quadrangular.
- Flower: Irregular (zygomorphic), ca. 20 mm (0.8 in.) long. Corolla bilabiate with a long upwards curved tube, pale yellow, hood-like upper lip with 2 violet teeth (1.5 mm long), lower lip 3-lobed. Sepals 4, united, calyx laterally flattened, inflated. Flowers subtended by lanceolate, almost yellow bracts. Stamens 4. Pistil of 2 fused carpels. Flowers borne in spike-like groups at end of stem and branches.
- Leaves: Opposite. Stalkless, lanceolate to almost linear, margins toothed. Leaves with 12–16 (ssp. vernalis) or 15–25 (ssp. apterus) pairs of veins.
- Fruit: A brown, flattened capsule enclosed within the calyx.
- Habitat: Ssp. vernalis: Roadsides, ditchbanks, field margins, fallows, seashore meadows. Ssp. apterus: Especially rye fields.
- Flowering time: June–August.
The narrow-leaved rattle absorbs nutrients from the roots of neighbouring plants. The shoot of this species is yellowish-green, the stem often dark-mottled.
In Finland, two subspecies are recognized. Ssp. vernalis has leaves with 12–16 pairs of veins, whereas the leaves of ssp. apterus have 15–25 pairs. The former is the common native variant, often met with in seashore meadows. Ssp. apterus is a rarely encountered casual weed.
