Symphyotrichum pilosum (Willd.) G. L. Nesom

Remark The words or terms in red (actually dark orange) in the text are defined in a glossary.

aug_25_05c.gthmb can't be loaded. Symphyotrichum pilosum is native to North America. It is an erect, stout, robust, leafy, much-branched, herbaceous, that is usually cespitose perennial between one to four feet high. Symphyotrichum pilosum is a higly variable species and is quite common in eastern North America. It has sterile leafy offshoots and erect fertile stems. Its roots are long and slightly thickened. The root system is initially fibrous, but develops a caudex on mature plants. The stems are initially green with lines of small white hairs, but they often turn brown and become bare of leaves with age. The flowering stems are rather long with conspicuous needle-like leaves, and they are held erect or somewhat horizontal to the ground.

Because Symphyotrichum pilosum is one of the last plants to remain in flower before a heavy frost, it is an important source of pre-winter nourishment for many of insects.

There are two varieties for the species;

The species belongs to the Asteraceae family.


In classical Greek : so that Symphyotrichum would refer to a plant having fruits with pappus and growing together, the case of the disk florets.

In Latin pilosus means covered with hair, hairy, which is quite the case of the pilosum variety but somewhat less the case of the pringlei variety.

Cyrus Guernsey Pringle (May 6, 1838-May 25, 1911) was an American botanist; he spent a career of 35 years cataloguing the plants of North America, especially those Mexico. He discovered many new species and varieties. Many species have a well deserved pringlei epithet.

Common names

Some of the vernacular names of Symphyotrichum pilosum are: Awl Aster, Frost Aster, Frost-weed Aster, Frostweed Aster, Hairy Aster, Hairy White Oldfield Aster, Heath Aster, Michaelmas Daisy, Nailrod, Old Field Aster, Pringle's Aster, Steelweed, White Heath Aster and White Oldfield Aster. The French vernacular names are Aster poilu for the pilosum variety and Aster de Pringle for the pringlei variety.


Symphyotrichum pilosum var. pilosum has also been known as: Symphyotrichum pilosum var. pringlei has also been known as:


Symphyotrichum pilosum is readily identifiable as belonging to the Asteraceae family. The distinctive feature of Symphyotrichum pilosum var. pilosum his its hairy, very fuzzy stem, as if coated with a thick frost, but the pringlei variety is not as hairy The hardened, sharp apices of the involucre are a good characteristic for field identification.

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pilosum variety pringlei variety

The species can get misidentified as Symphyotrichum lanceolatum (previously know as Aster simplex) but the stem of the later is not as hairy as that of the pilosum variety. The species is also similar to Symphyotrichum puniceum but the stem of the later is also less hairy and is usually purple in color. The species is often confused with Symphyotrichum ericoides, which inhabits the same kinds of open, prairie-like habitats; the latter can be distinguished by its smaller flower heads and spine-tipped phyllary apices.




Flower heads



Typical habitats of Symphyotrichum pilosum include disturbed areas of mesic to dry black soil prairies, openings in upland forests, savannas, gravelly sandbars of lakes, sandy shores, limestone glades, rocky cliffs and bluffs, pastures and abandoned fields, areas along roadsides and railroads, and various kinds of waste ground, dumps, quarries, etc.


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Symphyotrichum pilosum occurs throughout eastern North America from Nova Scotia and Maine in the northeast, southward to Georgia, westward through southern Québec and Ontario to Wisconsin, Iowa, Kansas, and Arkansas. The pilosum variety is an introduced species in British Columbia; its distribution is wider that that of the pringlei variety. The map at right shows the Canadian provinces and United-States states where the species can be found, the distribution of Symphyotrichum pilosum var. pilosum on the map at right and at left the distribution of Symphyotrichum pilosum var. pringlei.

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Symphyotrichum pilosum can be quite attractive because it is often covered with small white flowers during the fall, helping to extend the season of bloom in wildflower gardens and elsewhere.

Symphyotrichum pilosum var. pilosum is sometimes considered an agricultural weed; it is weedier that Symphyotrichum pilosum var. pringlei. It often invades disturbed areas, where it competes with many of the more common Eurasian weeds. The species is troublesome in the United States but a weed of minor importance in Canada. The species commonly occurs in fields following the first year of abandonment and may dominate in the second, or subsequent years.

Meleagris gallopavo (the Wild Turkey) may nibble at both the leaves and seeds. The Sylvilagus (the various species of Cottontail Rabbits) eats the tender growth of young leaves and stems occasionally, while Odocoileus virginianus (the White-Tailed Deer) may browse on the entire plant to a limited extent.


The photos of the gallery were taken either with one of the following: Minolta DiMAGE 7, Canon PowerShot A530, Canon Xt Rebel, usually with the EF-S60mm f/2.8 Macro USM objective, Fujifilm A 610 and EPSON Perfection 1650 (scanner).

The title in the window shows the date when the picture was taken, i.e. jan_30_06... would mean that the photo was taken on the 30th of January, the 06 is for the 6th picture taken that day. The month, day and picture number might be followed by a letter which I use to identify the system used to take the picture.

Click on the thumbnails to get larger view. The original photos are usually in TIFF format, the photos shown are generally in JPEG format, often of reduced dimensions (to fit in a 1600 by 1200 pixels display while leaving a bit of margin) for loading time reduction.

Plants, stems

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Flower heads

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