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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

ISOCOMA GOLDENBUSH
Subshrub; herbage glabrous, minutely scabrous, sessile- or stalked-glandular, long-soft-hairy, or tomentose. Stem: prostrate to erect, ± striate below, yellow-white or gray to red-brown, glabrous or variously hairy, often dotted with sessile resin glands. Leaf: alternate, sometimes clustered in axils, entire, toothed, or pinnately lobed, gland-dotted, sometimes gummy-resinous, light to dark gray-green. Inflorescence: heads discoid, in loose to tight cyme-like clusters, these borne at branch tips or in ± flat-topped or panicle-like 2° clusters; involucre obconic; phyllaries yellow-white proximally, cartilaginous, tips green; receptacle flat, epaleate. Flower: corolla yellow; tube narrowly cylindric, abruptly expanded into larger cylindric throat; lobes short, erect; style branch appendages triangular. Fruit: narrowly obconic, light tan, silky-hairy; hairs white, yellow, tan, or light red-tan; pappus of 1–2 series of white, ± yellow, or red-tan bristles ± 2 × fruit.
16 species: southwestern North America, Mexico. (Greek: equal hair-tuft, from flowers) [Nesom 2006 FNANM 20:439–445] Plants from southern San Diego Co. with pinnately lobed leaves resemble Isocoma tenuisecta Greene, not in California, but are more densely hairy.
Unabridged references: [Nesom 1991 Phytologia 70:69–114]

Key to Isocoma

1. Phyllary tip swollen, with a prominent linear to widely elliptic resin gland (resin glands rarely >= 2), often with additional minute dot-like resin glands

2. Leaves all entire or proximal leaves toothed or lobed ..... I. acradenia (2)

3. Phyllary tips rounded and not or occasionally weakly soft-pointed; flowers 18–24 ..... var. acradenia

3' Phyllary tips blunt to acute (inner ones), abruptly soft-pointed; flowers 20–27 ..... var. bracteosa (2)

2' Leaves all toothed or pinnately lobed

4. Flowers 10–13; phyllaries minutely awn-tipped ..... I. arguta (2)

4' Flowers 12–27; phyllaries rounded and not or minutely awn-tipped ..... I. acradenia (2)

5. Flowers 20–27; phyllaries abruptly soft-pointed ..... var. bracteosa (2)

5' Flowers 12–20; phyllaries rounded and not awn-tipped or very weakly awn-tipped ..... var. eremophila

1' Phyllary tip dotted with minute resin glands (rarely with >= 1 weakly developed larger resin glands)

6. Flowers 10–13; phyllaries minutely awn-tipped ..... I. arguta (2)

6' Flowers 15–28; phyllaries acute, not at all awn-tipped, or with weakly developed projection at tip ..... I. menziesii

7. Leaf oblong-oblanceolate to widely obovate, coarsely serrate, ± thick, fleshy; stem and leaves glabrous, glandless — plants decumbent or prostrate ..... var. sedoides

7' Leaf linear, narrowly oblong, or oblanceolate to obovate, entire, toothed, or shallowly lobed, not fleshy (or if fleshy, at least stem long-soft hairy); stem and leaves glabrous to long-soft hairy, tomentose, or glandular

8. Herbage stalked-glandular, without nonglandular hairs or finely and closely ± gray cobwebby-tomentose

9. Plant prostrate or decumbent to ± erect; leaves 2–4 mm wide; heads in ± flat-topped or panicle-like cluster; fruit generally 2.3–3.6 mm; s South Coast, s Channel Islands, s Peninsular Ranges ..... var. decumbens (2)

9' Plant strictly erect; leaves 4–10 mm wide; heads in ± flat-topped cluster; fruit generally 4–5 mm; s San Francisco Bay Area, n Inner South Coast Ranges ..... var. diabolica (2)

8' Herbage not prominently glandular, otherwise glabrous to long-soft-hairy or tomentose

10. Plant prominently long-soft-hairy or tomentose

11. Herbage finely and closely gray tomentose; leaves narrowly oblanceolate, entire or few-toothed; stems decumbent to erect ..... var. decumbens (2)

11' Herbage with long, spreading ± thick-based hairs; leaves oblanceolate or oblong-oblanceolate, at least proximal leaves toothed along most of margin; stems generally erect ..... var. vernonioides (2)

10' Plant glabrous or slightly hairy, sometimes resinous

12. Leaves entire or few-toothed at tip ..... var. menziesii

12' At least proximal leaves serrate

13. Corolla 6–7 mm; fruit (3.8)4.5–5 mm ..... var. diabolica (2)

13' Corolla 5–7 mm; fruit 2.3–3.6 mm ..... var. vernonioides (2)

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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