Isocoma menziesii

(Hooker & Arnott) G. L. Nesom
Phytologia 70: 93. 1991.
Common names: Pacific jimmyweed Menzies’ goldenbush
Basionym: Pyrrocoma menziesii Hooker & Arnott Bot. Beechey Voy., 351. 1838
Treatment appears in FNA Volume 20. Treatment on page 442. Mentioned on page 440.

Herbage glabrous or villlous, sometimes stipitate-glandular, not resinous. Leaf blades obovate to spatulate or oblanceolate to nearly linear, 5–40 mm, margins entire or toothed to lobed. Involucres (6–)7–9 × 6–8 mm. Phyllary apices green to yellowish, not aristate, sometimes with weakly developed, non- or weakly spinulose projection, gland-dotted, without resin pockets or pockets small, weakly developed (var. decumbens and var. menziesii). Florets (15–)18–25(–28); corollas 5–7 mm. Cypsela ribs not forming apical horns.


Varieties 5 (5 in the flora).

Selected References



1 Leaf blades mostly obovate, thick-fleshy, margins coarsely serrate; stems decumbent, prostrate, or pendent; herbage glabrous Isocoma menziesii var. sedoides
1 Leaf blades obovate to oblanceolate, usually not thick-fleshy, margins entire or toothed (if so then at least stems densely villous); stems erect to ascending or decumbent; herbage glabrous, villous, tomentose, or stipitate-glandular > 2
2 Herbage essentially glabrous, stipitate-glandular > 3
2 Herbage glabrous, villous, or tomentose, not prominently glandular or glands beneath other vestiture > 4
3 Stems prostrate to decumbent or ± erect; leaves 5–22 × 2–4 mm; heads in corymbiform to loose, paniculiform arrays; cypselae 2.3–3.6 mm; San Diego County southward Isocoma menziesii var. decumbens
3 Stems strictly erect; leaves 20–40 × 4–10 mm; heads in corymbiform arrays; cypselae (3.8–)4.5–5 mm; San Benito and Santa Clara counties Isocoma menziesii var. diabolica
4 Plants densely tomentose or villous > 5
4 Plants glabrous or glabrate > 6
5 Herbage finely and closely grayish-arachnoid-tomentose; leaf blades narrowly oblanceolate, 5–22 × 2–4 mm, margins entire or with 1–2 pairs of teeth distally Isocoma menziesii var. decumbens
5 Herbage hirtellous, villoso-pilose, or densely gray-tomentose (hairs flattened, vitreous, long); leaf blades linear to oblanceolate or spatulate-oblong, 10–40 × 2–6(–9) mm, at least proximal leaves with toothed margins Isocoma menziesii var. vernonioides
6 Leaf margins entire or with 1–2 pairs of teeth or shallow lobes distally Isocoma menziesii var. menziesii
6 At least proximal leaves toothed along most margins Isocoma menziesii var. vernonioides