Symphyotrichum pilosum (Willd.) G. L. Nesom
The words or terms in red
(actually dark orange) in the text are defined in a
is native to North America.
It is an erect, stout, robust, leafy, much-branched,
herbaceous, that is usually
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;
- Symphyotrichum pilosum var. pilosum that has stems
sparsely to densely hirsute;
its leaves are pilose (hence the
species and variety epithet); it is
chromosomic numbers (2n) are
32, 40, and 48;
- Symphyotrichum pilosum var. pringlei that has
glabrous stems and glabrous
or glabrate leaves; its number of
chromosomes (2n) is 48.
The species belongs to the
In classical Greek :
so that Symphyotrichum would refer to a plant having
fruits with pappus
and growing together, the case of the
(symphysis) means the growing together, union
(trichos) the genitif of θριξ
(thrix) means hair
In Latin pilosus means covered with hair, hairy, which is quite
the case of the pilosum variety but somewhat less the case of the
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
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
Symphyotrichum pilosum var. pilosum has also been known as:
Symphyotrichum pilosum var. pringlei has also been known as:
- Aster ericoides L. forma villosus (Torr. & A. Gray) Voss
- Aster ericoides L. var. pilosus (Willd.) Porter
- Aster ericoides L. var. platyphyllus Torr. & Gray
- Aster ericoides L. var. villosus (Michx.) Torr. & Gray
- Aster ericoides L. var. villosus Torr. & A. Gray
- Aster juniperinus E. S. Burgess
- Aster pilosus Willd. forma pulchellus Benke
- Aster pilosus Willd. var. platyphyllus
(Torr. & Gray) S. F. Blake
- Aster ericoides var. pringlei A. Gray
- Aster faxonii Porter
- Aster pilosus var. demotus S. F. Blake
- Aster pilosus var. pringlei (A. Gray) S. F. Blake
- Aster pringlei (A. Gray) Britton
Symphyotrichum pilosum is readily identifiable as belonging to the
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.
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
- single or multiple from the base;
- ascending to erect;
- glabrate to pilose,
the hairs around 2 mm long;
- glabrous or hairy in lines the the pringlei variety.
- slightly clasping the stem;
- with no petiole or a short one,
but the basal ones
- becoming much smaller as they ascend the flowering stems;
- from 1 to 6 cm long and from 0.5 to 1.5 cm wide;
- with ciliate margins that are
- with acute to rounded
- with elliptic to
- with the major veins parallel to the
- in open, leafy arrays, in the shape of a
- from 1/2 to 3/4 inch across;
- with a cylindric involucre, from 5 to 6 mm tall, and from 3 to 4 mm
- with from 10 to about 40 white (rarely pinkish or bluish) fertile
ray florets , the
ligules about 1 cm long and
from 1 to 2 mm wide and minutely notched at the
- with spreading phyllaries with the
tip very hardened (a good characteristic for field identification);
- with from 10 to about 50 yellow
disk florets from 5 to 8 mm broad,
with 5 stamens,
becoming reddish purple or brown (as may other
- pollinated by bees, wasps, flies
- Blooming from August to September in my area, 25 km north of Montréal.
- a brown achene;
- about 1 mm long;
- with a white pappus.
Typical habitats of Symphyotrichum pilosum include disturbed areas of
mesic to dry black soil prairies,
openings in upland forests, savannas, gravelly sandbars of lakes,
rocky cliffs and bluffs, pastures
and abandoned fields, areas along roadsides and railroads,
and various kinds of waste ground, dumps, quarries, etc.
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.
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.
The leaves were scanned at 300 dpi,
this allows to measure the dimensions of the leaves.