Symphyotrichum potosinum |
Symphyotrichum porteri |
|
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Santa Rita Mountain aster |
Porter's or smooth white aster, smooth white aster |
|
Habit | Perennials, 15–35(–45) cm, colonial or cespitose; rhizoma-tous. | Perennials, 10–50 cm, cespitose; usually with branched caudices, sometimes long-rhizomatous. |
Stems | 1–3+, ascending to erect (sometimes purple or purplish brown), glabrous or glabrate, sparsely hairy in leaf axils [villous to sericeous]. |
1–4+, ascending to erect (straight), glabrous. |
Leaves | thin, apices callous-pointed, faces glabrous or glabrate; basal usually withering by flowering, long-petiolate, petioles sheathing, sparsely ciliate, blades lanceolate, 40–110 × (3–)5–7 mm, bases attenuate, margins entire to crenulate, rarely with 1–2 teeth, apices obtuse to rounded, callus-pointed; proximalmost cauline sometimes withering by flowering, winged-petiolate or sessile distally, blades lanceolate to linear-lanceolate, 50–120(–180) × 1–6 mm, bases attenuate, margins entire, sparsely ciliate, apices acute; distal sessile, blades subulate to lanceolate, 10–50 × 1–2 mm, bases clasping, apices acuminate. |
thin, margins usually entire, sometimes very sparsely serrulate distally, scabrous, apices acute, mucronulate, faces glabrous; basal usually deciduous at flowering (new winter rosettes developed by flowering), petiolate (petioles narrow or ± winged, then appearing sessile, slightly sheathing, ciliate), blades oblanceolate to obovate or spatulate, 5–45+ × 2–6 mm, cuneate, apices obtuse; proximal cauline usually withering by flowering, petiolate or sessile (petioles winged, slightly clasping, ciliate), blades oblanceolate or lanceolate to linear-oblanceolate or -lanceolate, 40–80(–90) × 2–5(–6) mm, bases cuneate; distal sessile, blades linear-lanceolate to linear, ± falcate, 8–60 × 0.5–3 mm, reduced distally, bases cuneate to rounded-cuneate. |
Peduncles | 1–4(–6) cm, ascending, glabrate, bracts 1–4(–5), subulate to lanceolate, foliaceous. |
0.2–2.8 cm, bracteate, glabrous, bracts 1–3, linear to linear-lanceolate. |
Involucres | cylindric to hemispheric, (4.5–)5–7.3 mm. |
campanulate to cylindro-campanulate, 3.6–5(–6) mm. |
Ray florets | 14–27; corollas white, laminae (4.6–)5.6–7(–9.5)–10.3 × 1.3–2 mm. |
(12–)20–34(–42); corollas usually white, seldom pinkish, laminae 6.8–12 × 0.7–1.8 mm. |
Disc florets | 18–35(–42); corollas yellow, 3.5–5 mm, tubes shorter than funnelform throats (hairy), lobes± spreading, triangular, 0.5–0.7 mm. |
(30–)40–75(–103); corollas pale yellow becoming pink and later brown, (2.8–)3.1–3.9(–4.9) mm, tubes much shorter than narrowly funnelform throats, lobes triangular, (0.3–)0.5–0.7(–0.8) mm. |
Phyllaries | in 2–3(–5) series, subulate to lanceolate, bases indurate, margins hyaline, entire to erose, often ciliate, green zones linear-lanceolate (outer) or rhombic (inner), apices acute, faces glabrous [sparsely villous]. |
in 4–6 series, linear-lanceolate to -oblanceolate (outer) or oblong-lanceolate (inner), unequal, bases indurate 1/4–3/4 (sometimes outermost foliaceous), margins proximally narrowly scarious, erose, hyaline, distally ciliolate, green zones lanceolate, apices acute, ± spreading, involute, mucronulate, faces glabrous. |
Heads | (1–)3–20(–40), in paniculiform arrays, branches patent. |
in paniculiform arrays, branches ascending, ± densely leafy with narrow branch leaves. |
Cypselae | light brown to gray, narrowly obovoid to fusiform, sometimes ± compressed, 2–3 mm, 5-nerved, faces glabrate to sparsely strigillose; pappi white to cream, 3.5–5.5 mm. |
purple to stramineous, obovoid to oblanceoloid, compressed, 1–2 mm, 4–5-nerved, faces sparsely, finely strigillose; pappi white, 1.2–3.5 mm. |
2n | = 10. |
= 16. |
Symphyotrichum potosinum |
Symphyotrichum porteri |
|
Phenology | Flowering (Jun–)Jul–Sep. | Flowering late Jul–Sep. |
Habitat | Moist, muddy, sandy, or rocky soils along streams | Lower montane |
Elevation | 1500–1900 m (4900–6200 ft) | 1800–2900 m (5900–9500 ft) |
Distribution |
AZ; Mexico |
CO; NM; WY
|
Discussion | Of conservation concern. Symphyotrichum potosinum is known from Cochise County, Arizona, south into Mexico to northern Oaxaca. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Symphyotrichum porteri is the only western member of subsect. Porteriana; it grows in the foothills of the Rocky Mountains. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 20, p. 480. | FNA vol. 20, p. 513. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Aster potosinus, Aster lemmonii | Aster porteri, Aster ericoides var. strictus |
Name authority | (A. Gray) G. L. Nesom: Phytologia 77: 289. (1995) | (A. Gray) G. L. Nesom: Phytologia 77: 289. (1995) |
Web links |