Arida riparia
Arida mattturneri
alkali aster, Chiricahua Mountain tansy-aster
1–12+, erect or ascending, straight and rigid, sometimes sprawling from base, branching from base and distally, glabrous, glaucous.
10–40+, erect to ascending, slender, repeatedly branched, midstems glabrous or sparsely gland-dotted, often stipitate-glandular and sticky-viscid.
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.
basal (rosettes) and cauline;
sessile;
basal blades obovate, 40–60 × 1.5–3.5 mm, greatly reduced distally, bases broadened, margins 2-pinnatifid, faces stipitate-glandular;
distal margins entire or toothed, apices apiculate.
hemispheric, 10–12 × 10–16 mm (fresh).
campanulate, 5–6 × 6–8 mm (fresh).
50–80+;
laminae bluish purple to lavender, 10–12 mm, coiled after flowering.
9–13+;
laminae lavender, 10.5–11.5 mm, drooping in flower, coiling after flowering.
45–100+;
corollas yellow, 3.5–5 mm.
40–100+;
corollas yellow, 3.5–4.5 mm.
in 4–5 series, appressed, linear-lanceolate, 2–8 mm, bases whitish to tan, margins entire to laciniate, apices green, acute to acuminate, glabrous.
in 5–6 series, spreading to recurved distally, oblong-lanceolate, 1–6 mm, bases green, margins ± entire, apices green, rounded-acute, faces stipitate-glandular.
borne singly (terminal), often in loose, leafy, cymiform arrays.
10–13 (terminal) in loose, corymbiform arrays.
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.
obovoid-oblong, 1–1.5 mm, 8–12-nerved per face, faces densely sericeous;
pappi: ray 0;
disc white, setose, 3–4 mm.
= 10.
= 10.
Arida riparia
Arida mattturneri
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.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Arida mattturneri is recognized by its basal rosettes of 2-pinnatifid leaves, dense glandular pubescence on stems, leaves, and phyllaries, lavender ray florets, and epappose ray cypselae. The type locality is Blumberg Canyon, Presidio County. Turner and Nesom suggested that A. mattturneri may be related to A. turneri, which also has 2-pinnatifid proximal leaves, or to A. parviflora, which is perennial and sometimes also has epappose ray cypselae but smaller heads.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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