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four-o'clock, heart-leaf four-o'clock, heart-leaf umbrella-wort, heartleaf umbrellawort four-o'clock, umbrellawort, wild four-o'clock

wing four o'clock

Habit Herbs, forming hemispheric clumps 6–8 dm diam., glabrous or very sparsely puberulent.
Stems

usually erect or ascending, occasionally decumbent, leafy mostly in proximal 2/3 of plant, openly forked distally, 4–15 dm, basally usually glabrous or puberulent in 2 lines, rarely spreading-pubescent; distally stems usually puberulent in 2 lines, occasionally glabrate, rarely spreading glandular-pubescent.

2–4 dm.

Leaves

ascending at 45–80°, abruptly reduced to inflorescence;

petiole 0.2–2 cm;

blade green, ovate-lanceolate to ovate or triangular, 3–10 × 2–6.5 cm, usually ± thin, base obtuse, round, truncate, or cordate, apex acute to acuminate, rarely rounded, surfaces usually glabrous, sometimes puberulent or sparsely hispidulous.

spreading;

petioles of proximal leaves 0.5–0.7 cm;

blades of midstem leaves ovate to widely ovate, 4.5–9 × 3.5–5 cm, base obtuse to rounded, often oblique, apex obtuse, rarely acute.

Inflorescences

terminal and in upper axils, subumbellate clusters at ends of long, forked branches;

peduncle 5–20 mm, usually pubescent with ascending, often curved, glandular or eglandular hairs, crosswalls of hairs pale;

involucres pale green, often tinged pinkish, widely bell-shaped to almost rotate, 4–6 mm in flower, 8–15 mm in fruit, glabrous or glabrate but with minute curved hairs on margins, or rarely puberulent or pilose throughout, 50–90% connate, lobes ovate to broadly ovate.

Involucres

peduncle 3–10 mm;

involucres erect to pendent, 11–30 mm;

bracts 6–9, distinct or to 50% connate, apex acute to obtuse, rarely rounded.

Flowers

(2–)3(–5) per involucre;

perianth usually pink to reddish purple, rarely white, 1 cm.

6–9 per involucre;

perianth usually magenta, occasionally creamy white, bell-shaped, 1.5–1.8 cm.

Fruits

dark grayish brown to reddish brown (ribs and tubercles usually slightly paler), narrowly obovate and tapering at both ends, 3.4–5 mm, shaggy-pubescent with spreading, sometimes tufted, hairs, 0.3–0.4 mm, sometimes also with layer of minute hairs;

ribs usually irregularly and deeply notched, especially toward apex, round to bluntly angled, 0.5–0.75 times width of sulci, 0.5–1 times as wide as high;

sulci with pale small to tall tubercles that are sometimes horizontally lengthened and shelflike.

mottled olive green, with 10 slender, tan ribs, ellipsoid, 5.5–7 mm, rugulose, glabrous, secreting thick, heavy mucilage when wetted.

2n

= 58.

Mirabilis nyctaginea

Mirabilis alipes

Phenology Flowering late spring–early fall. Flowering spring–late summer.
Habitat Weedy areas in dry, often disturbed sites Gravelly or sandy soils in arid brushlands or pinyon-juniper woodlands
Elevation 100-2200 m (300-7200 ft) 1200-2000 m (3900-6600 ft)
Distribution
from FNA
AL; AR; AZ; CA; CO; CT; DC; DE; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; ON; QC; SK; Europe [Introduced in Mexico]
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; CO; NV; UT
[WildflowerSearch map]
[BONAP county map]
Discussion

Mirabilis nyctaginea is considered a noxious weed in some states. The holotype of Mirabilis ×collina Shinners is a hybrid between M. nyctaginea and M. albida. On the Great Plains, M. nyctaginea also appears to intergrade with M. albida. Prominence of the tubercles and redness of the fruits decreases in western populations. Near the Great Lakes, comparatively narrow-leaved plants with sparsely hirsute stems seem to be intergrades between M. nyctaginea and more or less hirsute M. albida. Mirabilis ×serotina Shinners is a hybrid between M. nyctaginea and M. glabra.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Hermidium was once maintained as a genus based on discrete involucral bracts. As discussed by G. E. Pilz (1978), distinct bracts are typical, but involucres with the five outermost bracts united to one-half their length are common.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 4, p. 55. FNA vol. 4, p. 44.
Parent taxa Nyctaginaceae > Mirabilis > sect. Oxybaphus Nyctaginaceae > Mirabilis > sect. Quamoclidion
Sibling taxa
M. albida, M. alipes, M. austrotexana, M. coccinea, M. gigantea, M. glabra, M. greenei, M. jalapa, M. laevis, M. latifolia, M. linearis, M. longiflora, M. macfarlanei, M. melanotricha, M. multiflora, M. oxybaphoides, M. pudica, M. rotundifolia, M. tenuiloba, M. texensis
M. albida, M. austrotexana, M. coccinea, M. gigantea, M. glabra, M. greenei, M. jalapa, M. laevis, M. latifolia, M. linearis, M. longiflora, M. macfarlanei, M. melanotricha, M. multiflora, M. nyctaginea, M. oxybaphoides, M. pudica, M. rotundifolia, M. tenuiloba, M. texensis
Synonyms Allionia nyctaginea, Oxybaphus nyctagineus Hermidium alipes, Hermidium alipes var. pallidium
Name authority (Michaux) MacMillan: Metasp. Minnesota Valley, 217. (1892) (S. Watson) Pilz: Madroño 25: 120. (1978)
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