Mirabilis melanotricha
Mirabilis rotundifolia
black-hair umbrellawort, four o'clock, mountain four-o'clock, Standley's four o'clock
roundleaf 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, 2–3 dm, leafy mostly in proximal 1/2, openly forked distally, spreading-soft hirsute throughout.
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.
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.
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.
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.
3 per involucre;
perianth bright purple-pink, 0.9–1.2 cm.
3 per involucre;
perianth purplish pink, 0.9–1.1 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.
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.
Mirabilis melanotricha
Mirabilis rotundifolia
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.)
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.)
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