Mentzelia micrantha

(Hooker & Arnott) Torrey & A. Gray

Fl. N. Amer. 1: 535. 1840.

Common names: San Luis or chaparral blazingstar
Illustrated
Basionym: Bartonia micrantha Hooker & Arnott Bot. Beechey Voy., 343, plate 85. 1839
Treatment appears in FNA Volume 12. Treatment on page 538. Mentioned on page 498, 531, 532.

Plants wandlike or candelabra-form, 10–80 cm. Basal leaves persisting; petiole present or absent; blade lanceolate to linear, margins irregularly deeply lobed to dentate. Cauline leaves: petiole present or absent (proximal leaves), absent (distal leaves); blade lanceolate to linear (proximal leaves), orbiculate to lanceolate (distal leaves), to 18 cm, margins irregularly deeply lobed to dentate proximally, dentate or entire distally. Bracts green, orbiculate to ovate, 3.4–6.6 × 2.5–5.9 mm, width 3/4 to ± equal length, often concealing capsule, margins sinuate or entire. Flowers: sepals 1–3 mm; petals yellow, 2-5 mm, apex acute; stamens 10–20, 1.5–4 mm, filaments heteromorphic, 5 outermost elliptic, distally 2-lobed, inner filiform, unlobed; styles 2–3 (–5) mm. Capsules cylindric, 6–13 × 1.5–2.5 mm, axillary curved to 20° at maturity, usually inconspicuously, occasionally prominently, longitudinally ribbed. Seeds 4–10, in 1 row distal to mid fruit, dark-brown or tan, dark-mottled, triangular prisms, surface ±smooth to minutely tessellate under 10× magnification; recurved flap over hilum absent; seed-coat cell outer periclinal wall flat. 2n = 18.


Phenology: Flowering Apr–Jun.
Habitat: Open, often recently-burned or disturbed chaparral or oak woodlands.
Elevation: 0–2300 m.

Distribution

V12 448-distribution-map.jpg

Calif., Mexico (Baja California)

Discussion

Mentzelia micrantha is easily distinguished from other species in sect. Trachyphytum by the presence of two lateral lobes on the filaments of the five outermost stamens. This characteristic is distinct from the filament lobes of some species in sect. Bicuspidaria, which occur on all or most stamens. Phylogenetic studies have found that M. micrantha is not closely related to species in sect. Bicuspidaria (L. Hufford et al. 2003; J. M. Brokaw and Hufford 2010).

Selected References

None.

Lower Taxa

None.

"equal" is not a number."not elongating" is not a number.

... more about "Mentzelia micrantha"
heteromorphic +
filiform +
Joshua M. Brokaw +
(Hooker & Arnott) Torrey & A. Gray +
not +  and persistent +
Bartonia micrantha +
lanceolate;linear orbiculate +
0 cm0 mm <br />0 m <br /> (18 cm180 mm <br />0.18 m <br />) +
orbiculate;ovate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.59 cm5.9 mm <br />0.0059 m <br />) +
0.6 cm6 mm <br />0.006 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
cylindric +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
San Luis or chaparral blazingstar +
Calif. +  and Mexico (Baja California) +
0–2300 m. +
curved +  and straight +
s--shaped +, clavate +, urceolate +, ovoid +, cylindric +, subcylindric +, lingulate +  and cup-shaped +
Open, often recently-burned or disturbed chaparral or oak woodlands. +
free +  and adnate +
unlobed +  and filiform +
cauline +  and basal +
entire +  and dentate +
entire +, sinuate +, lobed to dentate +, lobed +, irregularly deeply lobed +  and dentate +
elliptic +  and linear +
apical +, subapical +  and inferior +
inconspicuous +
connate +  and distinct +
spreading +  and erect +
hairy +  and glabrous +
obovate +, oblanceolate +, elliptic +, ovate +  and spatulate +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
Flowering Apr–Jun. +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
Fl. N. Amer. +
dark-mottled +, tan +  and dark-brown +
triangular +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
persistent +
lanceolate +  and narrowly ovate +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Illustrated +
adnate +, free +  and distinct +
included +  and exserted +
10 +  and 20 +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
decumbent +, clambering +  and erect +
papillate +
3-lobed +  and lingulate +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
less smooth +  and minutely tessellate +
Mentzelia micrantha +
Mentzelia sect. Trachyphytum +
species +
dendritic +  and unbranched +
straight +
candelabra-form +  and wand-like +