Pluchea sericea

(Nuttall) Coville

Contr. U.S. Natl. Herb. 4: 128. 1893.

Common names: Arrowweed
Illustrated
Basionym: Polypappus sericeus Nuttall Proc. Acad. Nat. Sci. Philadelphia 4: 22. 1848
Synonyms: Tessaria sericea (Nuttall) Shinners
Treatment appears in FNA Volume 19. Treatment on page 480. Mentioned on page 478, 479.

Shrubs or trees (not aromatic), 150–300 (–500) cm; roots not seen. Stems (densely leafy) sericeous, not glandular. Leaves sessile; blades lanceolate to narrowly lanceolate or narrowly oblanceolate, 1–5 × 0.2–1 cm, margins entire, faces sparsely to densely silvery sericeous, not glandular (minutely punctate). Heads in cymiform clusters. Involucres ± campanulate, 4–6 × 3–5 mm. Phyllaries pink to purplish, tomentose to villosulous (outer) to arachnose-ciliate or glabrate (inner). Corollas pink to purplish. Pappi persistent, bristles distinct (distally dilated in functionally staminate florets; cypselae glabrous). 2n = 20.


Phenology: Flowering mostly Mar–Jul (sometimes year-round).
Habitat: Floodplains, streambanks, dry lake beds, dunes, sand flats
Elevation: 40–1000 m

Distribution

V19-804-distribution-map.gif

Ariz., Calif., Nev., N.Mex., Tex., Utah, Mexico (Baja California), Mexico (Chihuahua), Mexico (Sonora)

Discussion

Pluchea sericea (with its woody habit and eglandular, densely arranged, sericeous leaves) is isolated among North American Pluchea. Torrey and Gray recognized its close similarity to the Asian Pluchea lanceolata (de Candolle) Oliver & Hiern, the type species of the Asian genus Berthelotia. It has been treated within Berthelotia and the South American and Central American segregate Tessaria, and a distinct genus (Eremohylema A. Nelson) has been created for it.

Pluchea sericea is more similar to the segregates than to herbaceous American groups; the delimitations of the genera are not clear. Tessaria was restricted to T. integrifolia Ruiz & Pavón, based on its single functionally staminate flower per head and corolla lobes cut nearly to the base of the limb, by H. Robinson and J. Cuatrecasas (1973). The sister species of T. integrifolia appears to be T. absinthoides (Hooker & Arnott) Cabrera [= Pluchea absinthoides (Hooker & Arnott) H. Robinson & Cuatrecasas]. Both species have inner phyllaries with reflexing tips, alveolate and paleate receptacles, pappus bristles basally united into a thick cup, and other distinctive floral features (G. L. Nesom 1989). It seems likely that the accepted definition of Tessaria may be expanded to two species or more broadly to include P. sericea and the species placed in Berthelotia. Alternately, Berthelotia (including P. sericea) might be accepted at generic rank, coordinate with Tessaria. In any case, it seems likely that P. sericea ultimately will be treated outside a more strictly circumscribed Pluchea.

Selected References

None.

Lower Taxa

None.
... more about "Pluchea sericea"
sessile-glandular +  and stipitate +
villous +, strigose +, sericeous +, puberulent +  and arachnose +
glabrous +  and glabrate +
obtuse;rounded +
scarious +
ovate +  and lanceovate or linear +
paniculiform +  and corymbiform +
indeterminate +  and determinate +
Guy L. Nesom +
(Nuttall) Coville +
not +  and clasping +
decurrent +
Polypappus sericeus +
compound +  and simple +
1 cm10 mm <br />0.01 m <br /> (5 cm50 mm <br />0.05 m <br />) +
lanceolate;narrowly lanceolate or narrowly oblanceolate +
0.2 cm2 mm <br />0.002 m <br /> (1 cm10 mm <br />0.01 m <br />) +
ribbed;smooth +
Arrowweed +
pink +  and purplish +
oblong-cylindric +
Ariz. +, Calif. +, Nev. +, N.Mex. +, Tex. +, Utah +, Mexico (Baja California) +, Mexico (Chihuahua) +  and Mexico (Sonora) +
40–1000 m +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Floodplains, streambanks, dry lake beds, dunes, sand flats +
indeterminate +
heterogamous +
each +  and sessile +
0.3 cm3 mm <br />0.003 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
campanulate +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
deltate +
denticulate +  and entire +
2-carpellate +
persistent +
Flowering mostly Mar–Jul (sometimes year-round). +
tomentose +  and villosulous +
Contr. U.S. Natl. Herb. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
4 +  and 8 +
setiform +
exalbuminous +
Illustrated +
stipitate +, winged +, branched +  and simple +
appendaged +  and truncate +
papillate +
Tessaria sericea +
Pluchea sericea +
species +
fibrous-rooted +  and taprooted +
200 cm2,000 mm <br />2 m <br /> (500 cm5,000 mm <br />5 m <br />) +
perennial +  and annual +
50 cm500 mm <br />0.5 m <br /> (200 cm2,000 mm <br />2 m <br />) +
fibrous-rooted +  and taprooted +
300 cm3,000 mm <br />3 m <br /> (500 cm5,000 mm <br />5 m <br />) +
tree +  and shrub +