Tonestus |
Tonestus graniticus |
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goldenweed, serpentweed |
granite serpentweed, Lone Mountain serpentweed |
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Habit | Perennials, 1–21 cm (cespitose, sometimes mat-forming; taproots usually ± well developed, poorly so in T. lyallii, caudices branched or rhizomes short). | Perennials, cespitose to ± mat-forming, 5.5–14 cm; with branched caudices surmounting well-developed taproots. | ||||||||||||
Stems | erect, simple, hairy and/or ± densely stipitate-glandular. |
(clothed with marcescent leaf bases) densely stipitate-glandular. |
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Leaves | basal and cauline; alternate; petiolate (basal and cauline) or sessile (cauline); basal blades 1-, 3-, or 5-nerved, linear to broadly spatulate; cauline progressively reduced distally (bases ± clasping), margins entire, coarsely and irregularly serrate, dentate, or lobed, sometimes ciliate, faces glabrous or scabrous, eglandular or stipitate-glandular. |
basal blades ovate to spatulate, 12–40 × 5–12 mm; cauline petiolate (proximal) to sessile and ± clasping (distal), blades oblong to broadly lanceolate, 4–28 × 1–8 mm, markedly reduced distally; 1- or very weakly 3-nerved, margins usually irregularly dentate, rarely (basal, distal) entire, faces densely scabrous (hairs multicellular, conic), stipitate-glandular. |
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Peduncles | 0–15 mm (often apparently bracteolate). |
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Involucres | narrowly to broadly campanulate, (5–28 ×) 6–20 mm. |
narrowly campanulate, 5–9 × 6–10 mm. |
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Receptacles | convex, pitted, epaleate. |
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Ray florets | 0, or 10–23(–35), pistillate, fertile; corollas yellow (tubes sparsely hairy, laminae narrowly elliptic, coiling at maturity). |
0. |
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Disc florets | 13–66, bisexual, fertile; corollas yellow, tubes (glabrous or sparsely hairy) shorter than narrowly funnelform to ± ampliate throats, lobes 5, erect or spreading, deltate to broadly lanceolate; style-branch appendages subulate to lanceolate. |
13–23; corollas funnelform to ± ampliate distally, 3.5–5.5 mm, scarcely exceeding involucres, lobes erect to slightly spreading, 0.8–1 mm, 1/5–1/4 corolla length; anthers 1.6–2.1 mm; style-branch appendages lanceolate, 0.7–1.1 mm, stigmatic lines 0.6–1.1 mm. |
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Phyllaries | 16–34(–44) in 3–4(–5) series, usually green, sometimes anthocyanic, 1- or weakly 3–5-nerved (flat), equal to unequal, sometimes chartaceous proximally, margins ciliolate or eciliate, faces often stipitate-glandular at least distally; outer ovate, oblong, or broadly lanceolate, often foliaceous (apices rounded, obtuse, or acute); inner linear to narrowly oblong, margins scarious, fimbriate (apices acute to acuminate, sometimes reflexed), faces sometimes stipitate-glandular distally. |
18–32, in 3–4 series, often reflexed distally, green, 1-nerved, unequal, proximally chartaceous and ± keeled, margins eciliate, faces stipitate-glandular; outer and mid ovate to oblong, 2–6 × 1–2 mm, apices obtuse to acute; inner linear to narrowly lanceolate, 4–6 × 1–2 mm, margins scarious, stipitate-glandular distally, apices acute to acuminate. |
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Heads | radiate or discoid, in usually racemiform, sometimes corymbiform arrays. |
(1–)3–7(–11), in racemiform or apparently corymbiform arrays. |
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Cypselae | cylindric to linear, terete, 4–12-nerved, faces glabrous or villous; pappi persistent, of 30–60 whitish, ± equal, brittle or flexible, fine, barbellate, apically attenuate bristles in 1 series (± equaling corollas). |
cylindric, 1.5–3 mm, weakly 4–7-nerved, faces strigose; pappus bristles 25–35, brittle. |
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x | = 9. |
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2n | = 18. |
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Tonestus |
Tonestus graniticus |
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Phenology | Flowering and fruiting mid–late summer. | |||||||||||||
Habitat | Crevices of granite outcrops | |||||||||||||
Elevation | 2400 m (7900 ft) | |||||||||||||
Distribution |
w North America |
NV |
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Discussion | Species 4 (4 in the flora). Recent work by L. Brouillet et al. (2004) and R. P. Roberts and L. E. Urbatsch (2004) has refined our understanding of the affinities of taxa included by G. L. Nesom and D. R. Morgan (1990) in Tonestus, some of which are now referred to Eurybia, Lorandersonia, or Toiyabea. In spite of these revisions, Tonestus appears to comprise at least three distinct elements. Two species primarily of the Rocky Mountains and ranges of the Pacific Northwest, T. lyallii and T. pygmaeus, resemble one another morphologically; molecular systematic studies by Roberts and Urbatsch suggested that these may be more closely related to different elements of the Solidagininae than they are to each other or to the remainder of the taxa included here in Tonestus. Likewise, while morphologic evidence indicates that T. eximius and T. peirsonii are closely related, the work of Roberts and Urbatsch placed the decaploid T. peirsonii in a clade with members of Lorandersonia wherein it is treated here; T. eximius is placed within a largely unresolved clade of the Solidagininae. Tonestus graniticus is included here mostly as a matter of convenience. It bears only superficial resemblance to other taxa included in the genus, differing in habit, array of heads, involucre, and hair type. The placement of this species within Solidagininae remains uncertain, although the work of Roberts and Urbatsch suggested that it may be related to Chrysothamnus. The treatment presented here must be considered tentative, at best. Tonestus pygmaeus is the nomenclatural type of the genus; further refinement of the taxonomy of this difficult group may require nomenclatural innovations. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Tonestus graniticus is known only from the Great Basin, from the east side of Lone Mountain, Esmeralda County. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 20, p. 181. | FNA vol. 20, p. 184. | ||||||||||||
Parent taxa | ||||||||||||||
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Synonyms | Haplopappus section T. | Haplopappus graniticus | ||||||||||||
Name authority | A. Nelson: Bot. Gaz. 37: 262. (1904) | (Tiehm & L. M. Schultz) G. L. Nesom & D. R. Morgan: Phytologia 68: 178. (1990) | ||||||||||||
Web links |