Symphyotrichum pilosum (Aster pilosus) awl aster Asteraceae ASPI; Bx, br, nb, pb, vc; Q, a, cu, dp, i, j, rw; K, do; R, c, cg, cp, fk, hs, is, jl, lp, mls, mm, ok, t, vn;


Aster pilosus.M.

Aster pilosus.M. B. Gargiullo ca. 2010

Symphyotrichum pilosum is a  short-lived perennial, C3 plant, fibrous rooted, but also colonial from rhizomes (Skinner 2005), stems usually hairy, pale, dull gray green, (occasionally hairless), 20-150 cm tall, from a persistent, woody root crown (caudex), that produces new overwintering rosettes each season from root sprouts that may be up to 1 m long, branches stiff (Chmielewski and Semple 2001b). 

Leaves alternate, leaves of basal rosette stalked, narrow, widest above middle, several new basal sprouts often appearing about time of flowering; lower stem leaves stalkless, blade to 10 cm long, 1 cm wide, inversely egg- to lance-shaped (obovate to lanceolate), usually hairy on both sides, margin hairy-fringed, deciduous as inflorescence develops, larger stem leaves often below tufts of small leaves about 0.4-0.7 cm long; branch leaves reduced upward to 0.5 cm long, 0.1 cm wide, linear, tip sharply pointed often with short bristle-like tip, grading into bracts of flower heads. 

Flowers rays white 16-35, about 0.3-0.8 cm long, 0.1 cm wide, disk flowers yellow, 20-40, petal lobes much shorter than tube;

Aster pilosus M. B. Gargiullo ca 2010.

Aster pilosus M. B. Gargiullo ca 2010.

flower heads 1.5-2 cm wide, 0.5-0.8 cm tall, bracteate base urn-shaped, bulging slightly at base, then constricted, flaring below rays from out-turned bract tips, tips green with pale, bristles, margins abruptly narrowed and thickened (in-rolled), base pale, flat; inflorescence branched, flower heads along one side of branches, or sometimes scattered; blooming Aug.-Oct. Flower visitors include honeybees (Apis mellifera), bumblebees (Bombus sp.), flies, moths, monarch butterflies (Danaus plexippus) and Clouded sulfur butterflies (Colias philodice) (Gargiullo personal observation); stems elongate under long-day light regime but flowering is induced by short days (less than 14 h sunlight), flower heads open, bloom and senesce over a period of up to two weeks (Chmielewski and Semple 2001). 

Fruit dry, 1-seeded (achene), 0.1 cm long, appressed-hairy (use lens), with a single circle of white bristles (pappus); dry, old flower bases open, with overlapping bracts. Seeds eaten by songbirds and small mammals. Seeds wind dispersed in fall and early winter. Stems and floral bases persistent through winter. 

Wetland status: UPL. 

Frequency in NYC: Frequent. 

Origin: Native. 

Aster pilosus.john

Aster pilosus (plumed achenes).John (Accessed 3/2014).

Habitat: Open, disturbed sites, roadsides, on dry soil or fill, often aggressive, weedy (Jones 1978; Uva et al. 1997). 

Notes:: Often a dominant plant in old fields, but eventually outcompeted by goldenrods, grasses, or mugwort. Needs disturbed soil to germinate and develop (Goldberg, 1987). Seeds need cold period to germinate, but germinate early in spring. Often becoming established with annual weeds on newly open soil. May bloom the first season if soil nutrients and moisture are high enough. Seedlings somewhat shade tolerant, larger plants very intolerant of shade (Keever 1979; Chmielewski and Semple 2001). Plants contain numerous phenolic compounds including chlorogenic and caffeic acids, known to inhibit seed germination and growth. Root extracts shown to inhibit germination growth of ragweed (Ambrosia artemisiifolia) and field hawkweed (Hieracium caespitosum). Grows on acid soil pH 5.2-7.0 (Skinner 2005) but also on calcareous soils, prefers high nutrient levels but will grow on sand dunes and shale outcrops. Tolerant of drought, rarely found in wetland edges. Aster pilosus is eaten by woodchucks, rabbits and voles (Microtus sp.) as well as by numerous insects, herbivorous insects are preyed on by various spiders that reside on the aster. Host to larvae of the pearly crescent butterfly, Phycoides tharos (Nymphalidae), (Tallamy 2003; Pyle 1981). Sometimes infected by the red rust fungus Coleosporium asterum (Basidiomycetes) and by mildews, but neither is lethal (Chmielewski and Semple 2001).