Arida riparia

(Kunth) D. R. Morgan & R. L. Hartman

Sida 20: 1414. 2003.

Common names: Chiricahua mountain tansy-aster alkali aster
Basionyms: Aster riparius Kunth in A. von Humboldt et al., Nov. Gen. Sp. 4(fol.): 72. 1818; 4(qto): 92. 1820
Synonyms: Machaeranthera riparia (Kunth) A. G. Jones Machaeranthera sonorae (A. Gray) Stucky
Treatment appears in FNA Volume 20. Treatment on page 405. Mentioned on page 402, 403.

Annuals, 25–60 cm; taproots slender to thick. Stems 1–12+, erect or ascending, straight and rigid, sometimes sprawling from base, branching from base and distally, glabrous, glaucous. Leaves mostly cauline; sessile (± appressed); blades oblanceolate, 20–30 × 3–5 mm, reduced distally, (thick, succulent) bases broadened, margins entire (incised to dentate in hybrids with A. parviflora) eciliate or with 1–8 cilia per side, apices linear, spiny-mucronate, glabrous; distal subulate, entire. Heads borne singly (terminal), often in loose, leafy, cymiform arrays. Involucres hemispheric, 10–12 × 10–16 mm (fresh). Phyllaries in 4–5 series, appressed, linear-lanceolate, 2–8 mm, bases whitish to tan, margins entire to laciniate, apices green, acute to acuminate, glabrous. Ray-florets 50–80+; laminae bluish purple to lavender, 10–12 mm, coiled after flowering. Disc-florets 45–100+; corollas yellow, 3.5–5 mm. Cypselae oblanceoloid, 2.5–3 mm, 11–13-nerved per face, faces sparsely sericeous; pappi: white, setose; ray 3–3.5 mm; disc 3–4 mm. 2n = 10.


Phenology: Flowering Apr–Sep.
Habitat: Low valleys, saline soils on mudflats, edges of playas
Elevation: 1300–1400 m

Distribution

V20-926-distribution-map.gif

Ariz., N.Mex., Mexico (Chihuahua), Mexico (Coahuila), Mexico (Durango), Mexico (Zacatecas)

Discussion

Arida riparia is a distinctive species recognized by its V-shaped branching, narrow, succulent, somewhat appressed, spiny-tipped leaves, and relatively large heads. It is known to hybridize with A. parviflora in southeastern Arizona and adjacent New Mexico. Specimens with dentate leaf margins usually represent hybrids.

Selected References

None.

Lower Taxa

None.

... more about "Arida riparia"
not tailed +, rounded +  and obtuse +
distinct +
subequal +
scarious +
usually triangular +  and linear +
usually deltate +  and lanceolate +
cymiform +  and leafy +
indeterminate +  and determinate +
Ronald L. Hartman +  and David J. Bogler +
(Kunth) D. R. Morgan & R. L. Hartman +
linear +  and lanceolate oblanceolate or obovate +
whitish +  and tan +
decurrent +
indurate to herbaceous +
broadened +
Aster riparius +
compound +  and simple +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
oblanceolate +
reduced +
3mm;5mm +
rugulose +  and muricate +
barbellulate +  and barbellate +
attenuate +
lanceolate +  and scalelike +
1 (?) +  and 8 (?) +
Chiricahua mountain tansy-aster +  and alkali aster +
not 2-lipped +  and actinomorphic +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
beaked +, 2-ribbed +  and 5-ribbed +
oblanceoloid +
fertile +  and bisexual +
fertile +  and bisexual +
equaling +
compressed +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
Ariz. +, N.Mex. +, Mexico (Chihuahua) +, Mexico (Coahuila) +, Mexico (Durango) +  and Mexico (Zacatecas) +
1300–1400 m +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Low valleys, saline soils on mudflats, edges of playas +
discoid +  and radiate +
indeterminate +
heterogamous +  and homogamous +
each +  and sessile +
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
hemispheric +
1 cm10 mm <br />0.01 m <br /> (1.6 cm16 mm <br />0.016 m <br />) +
bluish purple +  and lavender +
1 cm10 mm <br />0.01 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
triangular +
with 1-8 cilia +  and eciliate +
entire +  and laciniate +
2-carpellate +
persistent +
Flowering Apr–Sep. +
reflexed +, spreading +  and appressed +
linear-lanceolate +
0.2 cm2 mm <br />0.002 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
bearing subulate enations +, hairy +  and bristly +
exalbuminous +
gland-dotted +
straight +
ascending +  and erect +
1 +  and 12 +
appendaged +  and truncate +
papillate +  and smooth +
Machaeranthera riparia +  and Machaeranthera sonorae +
Arida riparia +
species +
1/4-1/2 times funnelform throats +
rhizomatous +  and taprooted +
60 cm600 mm <br />0.6 m <br /> (90 cm900 mm <br />0.9 m <br />) +
25 cm250 mm <br />0.25 m <br /> (60 cm600 mm <br />0.6 m <br />) +