Mirabilis melanotricha
Mirabilis coccinea
black-hair umbrellawort, four o'clock, mountain four-o'clock, Standley's four o'clock
red four o'clock, scarlet 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.
ascending to erect, 1.5–9 dm, glabrous basally, glabrous or rarely very sparsely puberulent 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.
usually ascending or spreading at 45–90°, dark grayish green, moderately thick and fleshy;
petiole 0–0.3 cm;
blade linear to linear-lanceolate, 4.5–10 × 0.1–0.5 cm, base attenuate, apex acute, surfaces glabrous or rarely with few small hairs adaxially, glabrous 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.
peduncle 4–8 mm, spreading stiff short hairy or glandular-pubescent, crosswalls of hairs pale;
involucres dark green, opaque, moderately veiny, 4–7 mm in flower, 4–8 mm in fruit, softly hirtellous or glandular-hirtellous, bracts 30–40% connate, lobes narrowly ovate or triangular.
3 per involucre;
perianth bright purple-pink, 0.9–1.2 cm.
perianth bright red-purple, 1.3–2 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, 4.5–6 mm;
ribs round, 0.5–0.8 times width of sulci, 0.5 times as wide as high, smooth or slightly warty or with warts equaling height of ribs;
sulci smooth.
Mirabilis melanotricha
Mirabilis coccinea
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 coccinea is easily confused with M. linearis var. linearis when the flowers are closed. The distinction is more difficult when plants are cleistogamous (phase Allionia gracillima in M. coccinea; phases A. pinetorum and Oxybaphus bodinii in M. linearis). In general, leaves of M. coccinea are oriented at an angle of 45° or greater to the stem, the distal portion of the main axis of the inflorescence is glabrous to 2–3 cm from the flowers, and the peduncles are sparingly short pubescent. In var. linearis, the leaves are generally oriented at 45° or less to the stem, the inflorescence is densely pubescent, and the peduncles are densely spreading-pubescent. Reports of the occurrence of M. coccinea in Texas (e.g., D. S. Correll and M. C. Johnston 1970) are apparently based on literature records and perhaps on a labeling error of a probable isotype collected by Charles Wright. No specimens have been seen from Texas. P. C. Standley (1911) discussed the unique nature of the fruit and perianth of this species relative to sect. Mirabilis and sect. Oxybaphus; in the original description, Torrey noted the species to be intermediate between Oxybaphus and Quamoclidion.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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