Mirabilis melanotricha
Mirabilis glabra
black-hair umbrellawort, four o'clock, mountain four-o'clock, Standley's four o'clock
smooth four-o'clock
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.
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.
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.
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.
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.
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.
3 per involucre;
perianth bright purple-pink, 0.9–1.2 cm.
1–3 per involucre;
perianth white to pale pink, 0.6–0.9 cm.
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.
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.
Mirabilis melanotricha
Mirabilis glabra
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.)
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.)
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