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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

smooth four-o'clock

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.

erect or ascending, sparsely to moderately leafy mostly in proximal 2/3, narrowly forked, usually with main axis, 5–20 dm, glabrous, glandular-puberulent, or puberulent with curved hairs, when pubescent, hairs usually densest distally.

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.

strongly ascending at 5–25°, progressively reduced toward inflorescence;

petiole 0–1.3 cm;

blade glaucous or grayish green, linear to narrowly ovate or ovate-oblong, 5–10 × 0.2–7.5 cm, thick and somewhat coriaceous, base attenuate to obtuse, round, truncate, or subcordate, apex acute to obtuse, occasionally round, surfaces glabrous to short pilose.

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.

usually terminal, sometimes also with short branches in distal axils, open, with main axis and short branches;

peduncle 5–10 mm, usually spreading glandular-pilose, sometimes merely puberulent or glabrous, crosswalls of hairs pale;

involucres pale green, widely bell-shaped, 3–6 mm in flower, 7–12 mm in fruit, glabrous except for few small hairs on margins to spreading glandular-pilose, 60–90% connate, lobes broadly ovate, rounded.

Flowers

(2–)3(–5) per involucre;

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

1–3 per involucre;

perianth white to pale pink, 0.6–0.9 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.

grayish to greenish brown (ribs usually paler), narrowly obovate and tapering at both ends, 4–5.5 mm, usually glabrous, sometimes very lightly puberulent with hairs 0.1 mm;

ribs narrow and keel-like to acute or acute-rounded, 0.2–0.5 times width of sulci, 0.5 times as wide as high, smooth;

sulci lightly to prominently tuberculate.

2n

= 58.

Mirabilis nyctaginea

Mirabilis glabra

Phenology Flowering late spring–early fall. Flowering late spring–early fall.
Habitat Weedy areas in dry, often disturbed sites Sandy soils in grasslands or among oaks, juniper, or mesquite, disturbed areas
Elevation 100-2200 m (300-7200 ft) 500-2100 m (1600-6900 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; CO; KS; NE; NM; OK; TX; UT; Mexico (Chihuahua)
[WildflowerSearch 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.)

As traditionally treated, Mirabilis carletonii (stems short pilose) and M. exaltata (stems glabrous), both from the eastern portion of the range of M. glabra, have leaves broader than 10 mm. Correlated with this is the presence of two to three flowers in the involucres. The narrower-leaved M. glabra, in the strict sense, has one or occasionally two flowers per involucre.

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

Source FNA vol. 4, p. 55. FNA vol. 4, p. 56.
Parent taxa Nyctaginaceae > Mirabilis > sect. Oxybaphus Nyctaginaceae > Mirabilis > sect. Oxybaphus
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. 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 Oxybaphus glaber, Allionia carletonii, Allionia exaltata, Allionia glabra, M. carletonii, M. exaltata, Oxybaphus carletonii, Oxybaphus exaltatus
Name authority (Michaux) MacMillan: Metasp. Minnesota Valley, 217. (1892) (S. Watson) Standley: Publ. Field Mus. Nat. Hist., Bot. Ser. 8: 304. (1931)
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