Mirabilis nyctaginea

Native

Dry. Prairies, disturbed sites. Full sun.

May to August

Pink to purple

1′ to 3′

This is a 1′ to 3′ tall, erect, perennial forb rising from a thick, dark, fleshy or woody, taproot.

The stems are hairless near the bottom and have 2 lines of fine, short hairs further upwards. They are usually erect or curve upward from the base, occasionally they recline on the ground with the tips ascending. They are forked near the top. Only the lower ⅔ of the stems are leaved.

The leaves are opposite, untoothed, green, thin, and usually hairless though sometimes sparsely hairy. They are 1″ to 4″ long, ¾″ to 2½″ wide. They are egg-shaped to round lance-shaped or sometimes triangular. The bases are heart-shaped, blunt, or rounded. The tips are pointed. They are on ¼″ to 1″ long leaf stalks and are held ascending at a 45° to 80° angle.

The inflorescence is several branched clusters at the end of each stem branch and in the upper leaf axils. The clusters appear at the end of long, forked, hairy branches. The clusters have 3 to 5 flowers each.

The flowers are ⅜″ wide. They have little or no fragrance. There are 5 pink to purple petal-like sepals. The sepals are fused at the base forming a tube, then flare outward. There are 5 bracts, ⅛″ to ¼″ long, at the base of the flower that are fused into a pale green, often tinged pinkish, saucer-shaped or broadly bell-shaped cup. The flowers open in the late afternoon, giving this plant its common name, remain open all night, and close in the morning.

The fruit is a one-seeded achene. It is subtended by the persistent, saucer-shaped fused bracts that have increased in size as the fruit developed, becoming ⅓″ to ⅔″ long.

Hairy four o’clock (Mirabilis hirsuta) has a hairy stem. The leaves are on shorter leaf stalks, are hairy, narrow and lance-shaped, and taper to the base. The bract cups are hairy. The flower clusters are in leaf axils, are loosely clustered on branches, or are scattered in open, widely spreading clusters, not at the end of the stems.

Narrow-leaved four o’clock (Mirabilis linearis) has linear leaves and larger flowers with much longer tubes.