Mirabilis nyctaginea (Michx.) MacMill.

Wild Four-O'Clock


CC = 0
CW = 3
MOC = 65

© SRTurner

Family - Nyctaginaceae

Habit - Perennial forb with woody roots and sometimes a woody base.

Stems - Ascending to erect, to 1.2 m, dichotomously branching, sometimes multiple from the base, somewhat 4-angled, glabrous or sparsely hairy, sometimes slightly glaucous.


© DETenaglia

Leaves - Opposite, simple, petiolate. Main leaf petioles 1-5 cm long. Leaf blades 3-15 cm long, oblong-ovate to triangular-ovate, broadly rounded to more commonly truncate or cordate at the base, narrowed or abruptly tapered to a bluntly or sharply pointed tip, glabrous or nearly so. Margins with some cilia or a few strigose hairs.

Mirabilis_nyctaginea_leaves1.jpg Leaf node.

© SRTurner

Mirabilis_nyctaginea_leaf1.jpg Leaf adaxial.

© SRTurner

Inflorescence - Dense terminal clusters of 3-6 flowers subtended by involucres, these broadly bell-shaped, 5-lobed, 5-6 mm long at flowering, becoming enlarged to 10-15 mm long at fruiting, glabrous or sparsely hairy on the surfaces, densely hairy along the margins, with 3-6 flowers. Pedicels to 1.5 cm.

Mirabilis_nyctaginea_inflorescence.jpg Inflorescence.

© SRTurner

Mirabilis_nyctaginea_inflorescence2.jpg Inflorescence.

© SRTurner

Flowers - Perianth 8-10 mm long, pink to reddish purple. Petals absent. Stamens 3-5. Pistil 1 per flower, the ovary superior but appearing inferior because of the closely enveloping perianth tube, consisting of 1 carpel, with 1 locule, the placentation basal. Style 1, the stigma globose or disclike.

Mirabilis_nyctaginea_involucres.jpg Calyx-like involucres.

© SRTurner

Mirabilis_nyctaginea_calyx.jpg Petalloid calyces.

© SRTurner

Mirabilis_nyctaginea_flower.jpg Flower close-up.

© DETenaglia

Fruits - Achenes 4-6 mm long (including the hardened perianth tube), densely hairy and roughened or finely warty on the sides and ribs, grayish brown to less commonly nearly black.

Mirabilis_nyctaginea_fruit.jpg Developing fruits.

© DETenaglia

Flowering - May - October.

Habitat - Upland prairies, streambanks, pastures, fields, roadsides, railroads, and disturbed areas.

Origin - Native to the U.S.

Lookalikes - None.

Other info. - This species occurs throughout Missouri. It is common across the north-central portion of the continental U.S., becoming scattered in the northeast and uncommon or absent elsewhere. The common term "four o'clock" refers to the tendency of many plants in this family to open their flowers in late afternoon. The flowers typically wither and drop early the next morning. Because of this, it is uncommon to find plants in full, open bloom, and the images above are somewhat atypical in this respect. More commonly the plants are seen in fruit, or with only small bits of the perianth visible as small patches of pink here and there. This, the distinctive involucres enclosing the flowers, and the broad opposite leaves make the plant relatively easy to identify.

Traditionally the plant (root tea) was used to treat fevers and to expel internal parasites. A poultice was applied externally to burns, sores, and swelling. Native Americans used the plant to treat coughs, sore mouth in babies, and in women after childbirth to reduce abdominal swelling. Various references assert that this species is toxic, but details are elusive.

Photographs taken in Marquette, MI., 9-10-03 (DETenaglia); also in Augusta, St. Charles County, MO, 5-11-2010, along the Katy Trail near Marthasville, Warren County, MO, 5-29-2013, on a roadside west of Washington, Franklin County, MO, 9-22-2014, and at Route 66 State Park, St. Louis County, MO, 5-11-2015 (SRTurner).