Mentzelia longiloba

J. Darlington

Ann. Missouri Bot. Gard. 21: 176. 1934.

Synonyms: Mentzelia multiflora subsp. longiloba (J. Darlington) Felger
Treatment appears in FNA Volume 12. Treatment on page 520. Mentioned on page 501, 502, 524.

Plants biennial or perennial, bushlike or candelabra-form, perennials with ground-level caudices. Stems solitary, erect, straight; branches distal or along entire stem, distal or proximal longest, antrorse, upcurved; hairy. Leaves: blade 35–112 × 4.3–27.1 mm, widest intersinus distance 2.3–15.3 mm, always on some leaves 4+ mm; proximal oblanceolate to elliptic, margins dentate to pinnate, teeth or lobes 12–30(–50), perpendicular to leaf axis or antrorse, 1–9 mm; distal lanceolate, base not clasping, margins serrate to pinnate, teeth or lobes 8–28, perpendicular to slightly antrorse, 0.8–7.5 mm; abaxial surface with simple grappling-hook, complex grappling-hook, and generally needlelike trichomes, adaxial surface with simple grappling-hook and needlelike trichomes. Bracts: margins entire or toothed to pinnate. Flowers: petals golden yellow, 11.3–20.4 × 2.9–7.2[–8.9] mm, apex acute to rounded, glabrous abaxially; stamens golden yellow, 5 outermost petaloid, filaments narrowly spatulate, slightly clawed, 10.4–17.8 × 1.9–5.2[–5.6] mm, with or without anthers, second whorl with anthers; anthers straight after dehiscence, epidermis smooth; styles (5.4–)8.5–10.9(–13) mm. Capsules cup-shaped to cylindric, [7.6–]9.1–16.4 × 5.7–9.2 mm, length usually to 2 times diam., sometimes a few more, base tapering to rounded, not longitudinally ridged. Seeds: coat anticlinal cell walls straight or sinuous, papillae 4–106 per cell.


V12 176-distribution-map.jpg

Ariz., Calif., Colo., N.Mex., Tex., Utah, n Mexico.


Varieties 4 (3 in the flora).

Variety pinacatensis J. J. Schenk & L. Hufford is known from the Mexican state of Sonora.

Selected References



1 Seed coat anticlinal cell walls straight, papillae 4–6 per cell; margins of proximal leaf blades dentate. Mentzelia longiloba var. chihuahuaensis
1 Seed coat anticlinal cell walls sinuous, papillae 10–106 per cell; margins of proximal leaf blades pinnate. > 2
2 5 outermost stamens without anthers; leaf blade margin teeth or lobes perpendicular to leaf axis; seed coat cell papillae 67–106 per cell. Mentzelia longiloba var. longiloba
2 5 outermost stamens with anthers; leaf blade margin teeth or lobes slightly antrorse; seed coat cell papillae 10–21 per cell. Mentzelia longiloba var. yavapaiensis