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desert blazing star

Habit Plants candelabra-form, 5–40 cm.
Basal leaves

persisting;

petiole present or absent;

blade linear, margins usually shallowly lobed, lobes rounded.

Cauline leaves

petiole absent;

blade ovate-lanceolate to linear, to 12 cm, margins shallowly lobed or entire.

Bracts

green, ovate to ovate-lanceolate, 3.6–4.7 × 1.6–2.3 mm, width 1/3–1/2 length, not concealing capsule, margins entire.

Flowers

sepals 2–4 mm;

petals yellow to orange proximally, yellow distally, 2–6 mm, apex acute or rounded;

stamens 10–30, 2–4 mm, filaments monomorphic, filiform, unlobed;

styles 2–4 mm.

Capsules

clavate, 12–27 × 1–2.5 mm, axillary curved to 180° at maturity, usually inconspicuously longitudinally ribbed.

Seeds

10–50, 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 tessellate under 10x magnification; recurved flap over hilum absent;

seed coat cell outer periclinal wall flat to slightly convex.

2n

= 18.

Mentzelia desertorum

Phenology Flowering Feb–Mar.
Habitat Sandy flats, washes, creosote-bush scrub.
Elevation 30–1000 m. (100–3300 ft.)
Distribution
from FNA
AZ; CA; Mexico (Baja California, Sonora)
[BONAP county map]
Discussion

Mentzelia desertorum, a diploid, is most similar morphologically to the tetraploid M. obscura, and the two species may be difficult to distinguish prior to seed maturation. However, many populations of M. desertorum have narrow basal leaves with short, widely spaced lobes that are unique among species within sect. Trachyphytum.

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

Source FNA vol. 12, p. 536.
Parent taxa Loasaceae > Mentzelia > sect. Trachyphytum
Sibling taxa
M. affinis, M. albescens, M. albicaulis, M. argillicola, M. argillosa, M. aspera, M. asperula, M. candelariae, M. canyonensis, M. chrysantha, M. collomiae, M. congesta, M. conspicua, M. crocea, M. cronquistii, M. decapetala, M. densa, M. dispersa, M. eremophila, M. filifolia, M. floridana, M. flumensevera, M. goodrichii, M. gracilenta, M. hirsutissima, M. holmgreniorum, M. hualapaiensis, M. humilis, M. integra, M. involucrata, M. inyoensis, M. isolata, M. jonesii, M. laciniata, M. laevicaulis, M. lagarosa, M. leucophylla, M. librina, M. lindheimeri, M. lindleyi, M. longiloba, M. marginata, M. memorabilis, M. mexicana, M. micrantha, M. mollis, M. monoensis, M. montana, M. multicaulis, M. multiflora, M. nitens, M. nuda, M. obscura, M. oligosperma, M. oreophila, M. pachyrhiza, M. packardiae, M. paradoxensis, M. pectinata, M. perennis, M. polita, M. procera, M. pterosperma, M. puberula, M. pumila, M. ravenii, M. reflexa, M. reverchonii, M. rhizomata, M. rusbyi, M. saxicola, M. shultziorum, M. sivinskii, M. speciosa, M. springeri, M. strictissima, M. thompsonii, M. tiehmii, M. todiltoensis, M. torreyi, M. tricuspis, M. tridentata, M. uintahensis, M. veatchiana
Synonyms Acrolasia desertorum
Name authority (Davidson) H. J. Thompson & J. E. Roberts: Phytologia 21: 280. (1971)
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