Mentzelia aspera |
Mentzelia obscura |
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dal-pega, rough stickleaf, tropical blazingstar, tropical stickleaf |
Pacific blazing star |
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Habit | Plants annual, without caudices or tubers. | Plants candelabra-form, 8–45 cm. |
Stems | erect to decumbent, to 30 cm. |
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Leaves | petiole 10–65 mm; blade hastate to ovate, usually basally lobed, sometimes unlobed, to 18 × 10 cm, base cuneate to truncate, margins serrate to crenate, apex acute. |
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Basal leaves | persisting; petiole present or absent; blade linear-lanceolate to linear, margins usually irregularly deeply lobed, lobes pointed. |
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Cauline leaves | petiole absent; blade ovate-lanceolate to linear, to 15(–22) cm, margins few-lobed or entire. |
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Bracts | green, ovate to ovate-lanceolate, 2.9–8.2 × 1.1–1.9 mm, width 1/8–1/2 length, not concealing capsule, margins entire. |
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Pedicels | (fruiting) 1–3 × 2 mm (often appearing absent because thick and continuous with capsule). |
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Flowers | petals orange or yellow, 5–15 × 3–7 mm, apex cuspidate, hairy abaxially at apex; stamens 20–30, 5 mm, filaments heteromorphic, 5 outermost narrowly spatulate, inner filiform; style 5 mm. |
sepals 2–6 mm; petals yellow to orange proximally, yellow distally, 3–8 mm, apex rounded or acute apex; stamens 20–40, 2–7 mm, filaments monomorphic, filiform, unlobed; styles 2–6 mm. |
Capsules | subcylindric to clavate, 9–30 × 3–3.5 mm, base tapering gradually, capsule and pedicel not well-differentiated. |
clavate, 11–31 × 1.5–3 mm, axillary curved to 250° at maturity, usually inconspicuously longitudinally ribbed. |
Seeds | 5–9 per capsule, pyriform to oblong, without transverse folds. |
15–50, in 2+ rows distal to mid fruit, tan, usually not, occasionally sparsely, dark-mottled, usually irregularly polygonal, occasionally triangular prisms proximal to mid fruit, surface colliculate under 10x magnification; recurved flap over hilum absent; seed coat cell outer periclinal wall domed, domes on seed edges less than 1/2 as tall as wide at maturity. |
2n | = 20. |
= 36. |
Mentzelia aspera |
Mentzelia obscura |
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Phenology | Flowering Aug–Oct. | Flowering Feb–May. |
Habitat | Arroyo and canyon bottoms, grasslands, desert scrub, riparian cottonwood and willow vegetation. | Sandy to rocky washes or slopes, desert scrub, Joshua-tree woodlands, roadsides. |
Elevation | 100–2000 m. (300–6600 ft.) | 200–1700 m. (700–5600 ft.) |
Distribution |
AZ; Mexico; Central America; South America; West Indies [Introduced in Atlantic Islands (Cape Verde Islands)]
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AZ; CA; NV; UT; Mexico (Baja California, Sonora)
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Discussion | Mentzelia aspera is uncommon in southern Arizona. It is the most widespread species of the genus and is regarded as weedy by some authors (H. J. Thompson and A. M. Powell 1981). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Mentzelia obscura is morphologically intermediate to M. desertorum and M. albicaulis and is known to occur in mixed populations with both species. Reliable discrimination among these species usually requires mature seeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 528. | FNA vol. 12, p. 540. |
Parent taxa | Loasaceae > Mentzelia > sect. Mentzelia | Loasaceae > Mentzelia > sect. Trachyphytum |
Sibling taxa | ||
Name authority | Linnaeus: Sp. Pl. 1: 516. (1753) | H. J. Thompson & J. E. Roberts: Phytologia 21: 284. (1971) |
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