Mirabilis nyctaginea |
Mirabilis rotundifolia |
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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 |
roundleaf four o'clock |
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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, 2–3 dm, leafy mostly in proximal 1/2, openly forked distally, spreading-soft hirsute throughout. |
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. |
usually widely ascending at 60–80°, abruptly reduced below inflorescence; petiole 0–0.9 cm; blade green adaxially, glaucescent abaxially, broadly ovate, ovate-triangular, or round, 4–7 × 3–6 cm, thick, moderately coriaceous, base cordate to round or cuneate, apex obtuse to round, surfaces glabrous or soft hirsute adaxially, soft hirsute abaxially. |
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. |
primarily terminal, few branched, open; peduncle 3–6 mm, spreading-pubescent, sometimes somewhat glandular, crosswalls of hairs pale; involucres grayish green, widely bell-shaped, 4–6 mm in flower, 7–8 mm in fruit, spreading-pubescent, 40–50% connate, lobes ovate. |
Flowers | (2–)3(–5) per involucre; perianth usually pink to reddish purple, rarely white, 1 cm. |
3 per involucre; perianth purplish pink, 0.9–1.1 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. |
pale olive brown, narrowly obovoid, 4–5 mm, ± evenly puberulent with hairs 0.1 mm; ribs round, 0.3–0.5 times width of sulci, 0.5 times as wide as high, slightly rugose (more so on side); sulci slightly darker than ribs, slightly rugose. |
2n | = 58. |
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Mirabilis nyctaginea |
Mirabilis rotundifolia |
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Phenology | Flowering late spring–early fall. | Flowering late spring-mid summer. |
Habitat | Weedy areas in dry, often disturbed sites | Open, calcareous, shaley outcrops |
Elevation | 100-2200 m (300-7200 ft) | 1600-1700 m (5200-5600 ft) |
Distribution |
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]
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CO |
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.) |
Of conservation concern. Mirabilis rotundifolia is clearly closely related to Mirabilis albida and may be only a variant. Mirabilis rotundifolia is in the Center for Plant Conservation’s National Collection of Endangered Plants. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 4, p. 55. | FNA vol. 4, p. 54. |
Parent taxa | Nyctaginaceae > Mirabilis > sect. Oxybaphus | Nyctaginaceae > Mirabilis > sect. Oxybaphus |
Sibling taxa | ||
Synonyms | Allionia nyctaginea, Oxybaphus nyctagineus | Allionia rotundifolia |
Name authority | (Michaux) MacMillan: Metasp. Minnesota Valley, 217. (1892) | (Greene) Standley: Publ. Field Mus. Nat. Hist., Bot. Ser. 8: 305. (1931) |
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