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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.

 

CENTROMADIA SPIKEWEED

Bruce G. Baldwin


Annual [perennial herb] 1–12 dm. Stem: prostrate to ± erect. Leaf: simple, basal and cauline, opposite proximally, often withered before flower, most alternate, ± sessile, oblanceolate to linear or lance-linear, proximal generally 1–2 pinnately lobed, lobes toothed or entire, sometimes bristly-ciliate, distal entire, generally spine-tipped, faces glabrous or scabrous and/or coarse- to soft-hairy or puberulent, often also glandular. Inflorescence: heads radiate, congested or in spike- to panicle- or umbel-like clusters; peduncle bracts generally spine-tipped; involucre ± obconic or urn-shaped, 3–8+ mm diam; phyllaries 5–75+, lanceolate or oblanceolate, each ± 1/2-enclosing ray ovary, falling with fruit or both persistent and head or flower branch dispersing as unit, scabrous and/or coarse- to soft-hairy or puberulent, often also glandular; receptacle flat to convex, minutely bristly; paleae subtending all or most disk flowers, free. Ray flower: 5–75+; corolla yellow, ray 2–6 mm. Disk flower: 6–200+, generally staminate; corolla 2–5 mm, yellow, tube < throat, tube/throat glabrous, lobes deltate, abaxially often minutely bristly; anthers ± red to dark purple or yellow to ± brown, tips ovate; style glabrous proximal to branches, tips ovate to awl-shaped, densely bristly. Fruit: ray fruit 2–3 mm, ± compressed, bulging abaxially, glabrous, beaked or elevated adaxially; pappus 0; disk pappus 0 or of 3–12 linear, awl-shaped or oblanceolate scales.
4 species: California, southern Oregon, northern Baja California (alien elsewhere in western United States, New York). (Latin: prickly Madia) [Baldwin & Strother 2006 FNANM 21:276–279] Self-sterile.
Unabridged disk flower: anther bases acute to sagittate.
Unabridged references: [Carlquist et al. 2003 Tarweeds and silverswords: evolution of the Madiinae; Venkatesh 1958 Evolution 39:1236–1241]

Key to Centromadia

1. Disk pappus 0; leaves not or minutely glandular ..... C. pungens

2. Paleae tips barely or not exserted, obtuse to acute, sometimes abruptly sharp-pointed; leaf margins bristly-ciliate, faces glabrous except midribs bristly ..... subsp. laevis

2' Paleae tips often strongly exserted, ± long-tapered, spine-tipped; leaf margins sometimes ciliate, at least near base, faces glabrous, scabrous, or coarsely hairy, midribs often bristly ..... subsp. pungens

1' Disk pappus of 3–5, linear to awl-shaped scales, or 8–12, narrowly oblanceolate to linear scales; leaves sometimes minutely to conspicuously glandular

3. Leaves densely soft- or coarse-hairy, stalked-glandular, glands yellow, brown, or black; anthers ± red to dark purple; disk pappus of 8–12, linear or narrowly oblanceolate scales ..... C. fitchii

3' Leaves glabrous, scabrous-puberulent, or ± coarsely to softly hairy, sometimes glandular, glands yellow; anthers yellow to ± brown or ± red to dark purple; disk pappus of 3–5, linear to awl-shaped scales ..... C. parryi

4. Anthers ± red to dark purple; leaves soft- or ± coarse-hairy or puberulent, stalked-glandular; paleae often with 2 purple lines along inner edges of scarious margins ..... subsp. australis

4' Anthers yellow or ± brown; leaves glabrous, scabrous-puberulent, or ± coarse-hairy, not soft-hairy, glandular or not; paleae lacking purple lines.

5. Leaves scabrous-puberulent and generally ± coarse-hairy or bristly-ciliate, not glandular or glands minute, scattered; involucre 3.5–5 mm; ray 2–3 mm ..... subsp. rudis

5' Leaves glabrous or coarsely hairy to puberulent, glandular or not; involucre 4–10 mm; ray 2.5–5(6) mm.

6. Peduncle bracts seldom glandular, sometimes with minute, stalked, ± yellow glands among nonglandular hairs; ray 2.5–3(4.5) mm ..... subsp. congdonii

6' Peduncle bracts coarsely glandular, glands sessile or short-stalked, yellow; ray 3–5(6) mm ..... subsp. parryi

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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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