Anagallis arvensis L.

Scarlet Pimpernel

© SRTurner

Family - Primulaceae

Habit - Annual forb with fibrous roots.

	Roots.
© SRTurner

Stems - Spreading, branched at base, to 30 cm, branching, 4-angled, glabrous, sometimes rooting at the nodes.

	Stem.
© DETenaglia

	Stem and node.
© SRTurner

Leaves - Opposite, entire, sessile, ovate, to 1.6 cm long, 1.0 cm broad, clasping or not, with brown speckles below, glabrous, margins somewhat tuberculate.

	Leaves, adaxial.
© SRTurner

	Leaf, abaxial.
© SRTurner

	Pressed leaves.
© DETenaglia

Inflorescence - Solitary flowers from leaf axils. Peduncles to 2 cm, glabrous, recurved in fruit.

	Inflorescence.
© SRTurner

Flowers - Calyces of 5 free sepals, 3-4 mm long, the margins membranous. Corollas deeply 5-lobed, 3-5 mm long, saucer-shaped, the lobes obovate, usually orange-red, less commonly white or blue, the margins with inconspicuous stalked glands or minutely toothed. Stamens 5, the filaments attached at the corolla base, hairy, purple toward the tip, the anthers yellow. Ovary globose, with numerous ovules, the single style 1.5-2.0 mm long, slender.

	Calyx.
© SRTurner

	Corolla.
© DETenaglia

	Corolla.
© SRTurner

	Flower and young fruit.
© SRTurner

Fruits - Globose capsules, 3-4 mm long, golden brown, membranous, with circumscissile dehiscence. Seeds numerous, angular, the surface tuberculate, dark brown.

	Immature fruits.
© SRTurner

	Mature fruit.
© DETenaglia

Flowering - May - September.

Habitat - Roadsides, pastures, waste ground, disturbed sites. Typically in moist soil.

Origin - Native to Eurasia.

Lookalikes - None.

Other info. - This pretty little plant can be found in scattered locations throughout much of Missouri, though it is not particularly common. It is easy to identify because of its sessile, opposite leaves, orange-red flowers, and globose fruits. The flowers look like nothing else which grows wild in the state. The fruits of this species are globose, circumscissile capsules which contain many tiny seeds. The plant can form mats, since it sometimes roots at nodes.

Steyermark and Yatskievych both list two forms for the state. Subspecies arvensis, shown above, has red-orange corollas, and ssp. caerulea has blue corollas. The latter form is much less common but perhaps more striking.

Anagallis arvensis produces toxins that are poisonous to livestock, and an irritant in the plant hairs can cause dermatitis in humans. The common name "poor man's weatherglass" comes from the propensity of the flowers to close in cloudy weather and reopen in sun.

Photographs taken off Highway 64, outside of St, Louis, MO., 8-7-05 (DETenaglia); also adjacent to I-57 in Iroquois County, IL, and at the Whiskey Creek Sheep Farm, near Krakow, Franklin County, MO, 6-3-2021 (SRTurner).