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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.

 

HOLOCARPHA TARWEED, TARPLANT

Bruce G. Baldwin


Annual 1–12 dm, aromatic. Stem: ± erect. Leaf: proximal opposite or in rosette, generally withered before flower, most alternate, sessile, linear to oblanceolate, serrate, or minutely so, or entire, coarse-hairy to strigose, silky-, or ± shaggy-hairy, distal sometimes also stalked-glandular and/or gland-dotted, tips of distal leaves generally each with a pit-gland. Inflorescence: heads radiate, 1 or in ± flat-topped, panicle-, raceme-, or spike-like clusters or in tight groups; peduncle bracts each with terminal pit-gland; involucre ± obconic or bell-shaped to ± spheric, 4–8+ mm diam; phyllaries 3–16 in 1 series, elliptic, oblanceolate, or obovate, each generally 1/2 enveloping a subtended ray ovary, falling with fruit, abaxially with pit-gland-tipped cylindrical outgrowths and glabrous or ± shaggy, bristly, and/or sessile- or stalked-glandular; receptacle flat to convex, glabrous; paleae subtending all or most disk flowers. Ray flower: 3–16; corolla yellow, ray 4–6.5 mm, lobes 1/8–1/2 length of ray, ± parallel. Disk flower: 9–90, some bisexual, most staminate; corolla 2.5–5 mm, yellow, tube <= throat, lobes deltate; anthers yellow to ± brown or ± red to dark purple, tips ovate to ovate-deltate; style glabrous proximal to branches, tips awl-shaped to bristle-like, densely hairy. Fruit: ray fruit ± 2.5–4 mm, nearly round in ×-section (except ± flattened adaxially) or ± 3- angled (abaxially generally ± widely 2-faced, adaxially ± flattened to slightly bulging), glabrous, tip beaked, beak adaxial, ascending, pappus 0; disk fruit ± club-shaped, glabrous, tip beakless, pappus 0.
4 species: California. (Greek: whole chaff, for bracts throughout receptacle) [Baldwin & Strother 2006 FNANM 21:287–289] ± identical forms often intersterile in Holocarpha heermannii and Holocarpha virgata. Self-sterile.
Unabridged disk flower: anther bases sagittate.
Unabridged references: [Palmer 1982 Ph.D. Dissertation, Univ of California, Davis]

Key to Holocarpha

1. Anthers yellow to ± brown

2. Stem notably stalked-glandular; phyllaries each with 25–50 pit-gland-tipped outgrowths and minutely sessile- or stalked-glandular and puberulent or minutely bristly; involucre bell-shaped to ± spheric; heads 1 or in panicle- or raceme-like clusters ..... H. heermannii

2' Stem resinous distally, not notably stalked-glandular; phyllaries each with (0)5–15(20) pit-gland-tipped outgrowths and generally glabrous or minutely sessile- or stalked-glandular (bristly); involucre ± obconic to ± spheric; heads in flat-topped or panicle-like clusters ..... H. obconica

1' Anthers ± red to dark purple

3. Heads 1, in tight groups, or in spike-like clusters of tight groups; ray flowers 8–16; disk flowers 40–90 ..... H. macradenia

3' Heads 1, at ends of branches, or in ± raceme- to spike-like clusters; ray flowers 3–8; disk flowers 9–25+ ..... H. virgata

4. Stem branches ± upcurved, ± pliable; peduncles 0–5(15) cm ..... subsp. elongata

4' Stem branches ± straight, ± rigid; peduncles 0–5+ cm ..... subsp. virgata

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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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