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black-hair umbrellawort, four o'clock, mountain four-o'clock, Standley's four o'clock

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

Stems

erect or strongly ascending, leafy mostly in proximal 2/3 of plant, openly forked distally, 5–12 dm, pubescent basally with minute curved hairs in 2 lines, spreading glandular-pilose distally.

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.

Leaves

ascending at 10–60°, progressively reduced toward infloresence;

petiole 0.8–3 cm;

blade bright green, narrowly triangular-ovate to ovate, 3–10 × 0.8–4 cm, ± thin, base acute, obtuse, truncate, or cordate, apex acute to attenuate, or obtuse, often rounded at tip, surfaces glabrous or rarely puberulent.

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.

Inflorescences

axillary and terminal, few branched, ± evenly forked and open;

peduncle 2–9 mm, spreading glandular-villous, crosswalls of hairs dark purple or black;

involucres blushed with dark violet or black, at least in median region, widely bell-shaped, 3–6 mm in flower, 4–7 mm in fruit, spreading viscid-villous, 40–50% connate, lobes oblong to ovate, apex broadly acute.

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.

Flowers

3 per involucre;

perianth bright purple-pink, 0.9–1.2 cm.

(2–)3(–5) per involucre;

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

Fruits

dark grayish to blackish brown, sometimes dark, dull, reddish brown, narrowly obovoid, 3–4 mm, spreading-pilose, hairs often apearing loosely shaggy and somewhat tufted, (0.1–)0.2–0.3 mm;

ribs ± same color as sulci, low and round, 0.7–1 times width of sulci, 0.5 times as wide as high, slightly rugose or warty;

sulci almost smooth to slightly rugose or with very low tubercules.

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.

2n

= 58.

Mirabilis melanotricha

Mirabilis nyctaginea

Phenology Flowering mid summer–early fall. Flowering late spring–early fall.
Habitat Conifer woodlands, mountain meadows, roadsides Weedy areas in dry, often disturbed sites
Elevation 1900-3000 m (6200-9800 ft) 100-2200 m (300-7200 ft)
Distribution
from FNA
AZ; CO; NM; TX; Mexico
[WildflowerSearch map]
[BONAP county map]
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]
Discussion

The erect habit, bright green and usually glabrous foliage, and dark involucres of Mirabilis melanotricha are distinctive in combination. Once collected and pressed, M. melanotricha becomes yet another “difficult” Mirabilis. In 1911, P. C. Standley noted that this species (as Allionia melanotricha) was one of the most variable in the genus, and in 1918 he submerged it in A. comata, which in the field is a grayish green, clump-forming, glandular-pubescent plant with decumbent-ascending stems. Mirabilis melanotricha occurs in more mesic situations mostly at elevations above M. comata (here in synonymy in M. albida). It intergrades into M. linearis along its northern edge and lower elevations in New Mexico through M. linearis var. decipiens (Standley) S. L. Welsh. In the northeastern portion of its range, it may intergrade with M. nyctaginea; fruits in that region sometimes are slightly more reddish and more tuberculate than usual. Along the eastern portion of its range, it also intergrades into M. albida, as plants become more pubescent and fleshy. B. L. Turner (1993b) noted that M. comata (apparently in the sense of its common usage, as applied to plants here classified as M. melanotricha) might remain distinct from his concept of M. albida, which included C. F. Reed’s (1969) comprehensive M. oblongifolia.

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

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.)

Source FNA vol. 4, p. 52. FNA vol. 4, p. 55.
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. multiflora, M. nyctaginea, 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. multiflora, M. oxybaphoides, M. pudica, M. rotundifolia, M. tenuiloba, M. texensis
Synonyms Allionia melanotricha Allionia nyctaginea, Oxybaphus nyctagineus
Name authority (Standley) Spellenberg: Phytologia 85: 99. (1999) (Michaux) MacMillan: Metasp. Minnesota Valley, 217. (1892)
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