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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

Colorado four-o'clock, Froebel's four-o'clock, giant four o'clock

Habit Herbs, forming hemispheric clumps 6–10 dm diam., glabrous or densely pubescent.
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.

4–7 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 2–4 cm;

blades of midstem leaves ovate to widely ovate, sometimes suborbiculate, rarely reniform, 5–10 × 4–8 cm, base rounded to cordate, often asymmetric, apex acute or acuminate to obtuse, rarely rounded.

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 4–75 mm;

involucres erect or ascending, 33–35 mm;

bracts 5, usually more than 50% connate, apex acute to obtuse or ovate.

Flowers

(2–)3(–5) per involucre;

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

6 per involucre;

perianth magenta, funnelform, 2.5–6 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.

brown to black, with 10 slender, tan ribs alternating with 10 dark brown ribs, or ribs inconspicuous, ovoid or globose, 6–11 mm, smooth to rugulose, glabrous or pubescent, secreting mucilage or not when wetted.

2n

= 58.

= 66.

Mirabilis nyctaginea

Mirabilis multiflora

Phenology Flowering late spring–early fall.
Habitat Weedy areas in dry, often disturbed sites
Elevation 100-2200 m (300-7200 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
AZ; CA; CO; NM; NV; TX; UT; n Mexico
[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.)

Varieties 3 (3 in the flora).

G. E. Pilz (1978) recognized three partially sympatric varieties based on presence or absence of mucilage production in the fruits, fruit color, and apical acuteness of involucral bracts. Overall, populations are poorly differentiated, and in some areas plants represent a “collage” (Pilz’s term) that combine characteristics of different varieties; S. L. Welsh et al. (1987) recognized no varieties. Mirabilis multiflora is used in the Southwest in a minor way in xeriscapes. Among indigenous peoples, it has been used as food and medicine (V. L. Bohrer 1975; L. S. M. Curtin 1947).

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

Key
1. Fruits tuberculate, mucilaginous when wetted; involucral bracts obtuse
var. glandulosa
1. Fruits smooth to slightly tuberculate, not mucilaginous when wetted; involucral bracts acute
→ 2
2. Fruits dark brown to black, ribs inconspicu- ous
var. multiflora
2. Fruits light brown, with 10 slender, tan, longitudinal ribs alternating with 10 brown, often interrupted ribs.
var. pubescens
Source FNA vol. 4, p. 55. FNA vol. 4, p. 45.
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. 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. nyctaginea, M. oxybaphoides, M. pudica, M. rotundifolia, M. tenuiloba, M. texensis
Subordinate taxa
M. multiflora var. glandulosa, M. multiflora var. multiflora, M. multiflora var. pubescens
Synonyms Allionia nyctaginea, Oxybaphus nyctagineus Oxybaphus multiflorus, Quamoclidion multiflorum
Name authority (Michaux) MacMillan: Metasp. Minnesota Valley, 217. (1892) (Torrey) A. Gray: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 173. (1859)
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