Downy Ragged
Goldenrod
Solidago petiolaris
Aster family (Asteraceae)
Description:
This perennial herbaceous plant is 1¼–4' tall, producing either
solitary or multiple leafy stems from the same root system. The stems
are light green, reddish green, or light to medium brown; they
are terete and sparsely to moderately short-pubescent. Abundant
alternate leaves occur along each stem that become gradually smaller in
size as they ascend. The leaf blades are 1-4" long and ¼–1" across;
they are elliptic to broadly elliptic, or lanceolate-elliptic, or
oblanceolate-elliptic in shape. The margins of leaf blades are entire
(toothless) to slightly toothed toward their tips and they are
short-ciliate. The upper blade surface is yellowish green or medium
green and sparsely covered with minute stiff hairs, providing it with a
slightly rough texture; the lower blade surface is light to medium
green and glabrous to short-pubescent along the major veins. The
leaf blades are either sessile or they have short petioles. Each stem
terminates in a cylindrical panicle of flowerheads about 4-10" long.
The branches and peduncles of the panicle are light green and more
or less covered with short hairs that are usually glandular. Leafy
bracts up to 1" long and ¼" across occur along these branches and at
the bases of peduncles; these bracts are similar in appearance to
the leaves, except they are smaller in size. Individual flowerheads are
about 6 mm. (¼") long and 3-4 mm. across.
Each flowerhead has 5-10 ray
florets that surround a dense head of 8-20 disk florets. The ray
florets are pistillate (female), while the disk florets are perfect
(both male and female). The spreading petaloid rays of the flowerhead
are golden yellow and narrowly oblong in shape. The tubular corollas of
the disk florets are yellow and they have 5 narrow lobes along their
upper rims. The base of each flowerhead has a cylindrical urn-shape
that is tapered at its base; it is surrounded by phyllaries (floral
bracts) in about 4 overlapping series. The phyllaries are light green,
linear-lanceolate in shape, and either minutely pubescent or
glandular-pubescent (usually the latter); these phyllaries are strongly
recurved toward their tips. The blooming period occurs from late summer
to mid-autumn, lasting about 3-4 weeks. Afterwards, the florets are
replaced by achenes with small tufts of hair; they are distributed
by the wind. The bodies of these achenes are about 3 mm. long,
bullet-shaped, and either glabrous or slightly short-pubescent. The
root system is fibrous and sometimes long-rhizomatous; an older plant
usually develops a swollen caudex. This plant spreads by reseeding
itself or it can form clonal offspring from rhizomes.
Cultivation:
The preference is partial sun, mesic to dry conditions, and a somewhat
acidic soil containing rocky material or sand. This plant will adapt to
cultivation, however it may require staking to prevent it from toppling
over.
Range
& Habitat: Downy Ragged Goldenrod is
native to
southern Illinois, where it is uncommon, while elsewhere within the
state it is absent (see Distribution
Map). Illinois lies along the
northern range-limit of this plant; it occurs primarily in
south-central and southeast USA. Habitats include upland woodlands,
upland savannas, thinly wooded rocky bluffs, thickets, glades with
acidic bedrock, and rocky prairies. In the wooded habitats where this
plant occurs, they are typically dominated by oaks and hickories.
Outside of Illinois, Downy Ragged Goldenrod also occurs in sandy mixed
woodlands (where both hardwood deciduous trees and conifers are
present). This plant is normally found in high quality natural areas.
Occasional wildfires are probably beneficial in maintaining its
populations.
Faunal
Associations: Very little is known about the
floral-faunal
relationships of Downy Ragged Goldenrod specifically. This goldenrod is
a significant source of nectar for migrating Monarch butterflies in
Arkansas (Rudolph et al., 2006) and the larvae of a leaf beetle, Microrhopala
excavata, mine its leaves (Clark et
al., 2004). For
goldenrods (Solidago spp.) in general, the nectar
and pollen of the
flowerheads attract a wide variety of insects, including honeybees,
bumblebees, little carpenter bees (Ceratina spp.),
leaf-cutter bees
(Megachile spp.), Halictid bees, masked bees (Hylaeus
spp.), Andrenid
bees, wasps, Syrphid flies and other flies, butterflies, skippers, and
beetles. Several Andrenid bees are oligoleges (specialist pollinators)
of goldenrods; this includes Andrena hirticincta, Andrena
nubecula, Andrena placata, Andrena
simplex,
and Andrena solidaginis. In addition,
a plasterer bee, Colletes simulans armata, is an
oligolege of
goldenrods. A wide variety of insects feed destructively on the
foliage, flowerheads, stems, roots, and plant juices of various
goldenrods. These species include leaf beetles (Microrhopala
spp., Ophraella spp., Trirhabda
spp.),
larvae of leaf-miner flies (Calycomyza
spp.), larvae of gall flies (Asteromyia spp.,
Rhopalomyia spp.), plant
bugs (Lygus spp., Polymerus spp.,
Slaterocoris spp.), Corythucha
marmorata (Goldenrod Lace Bug), aphids (Uroleucon
spp.), treehoppers
(Stictocephala spp.), Aonidomytilus
solidaginis (Goldenrod Scale),
larvae of Gelechiid moths (Dichomeris spp.), larvae
of Schinia nundina (Goldenrod Flower Moth) and
other Noctuid moths, larvae of
Tortricid
moths (Epiblema spp., Eucosma spp.,
Phaneta spp.), and grasshoppers
(Melanoplus spp.); see Clark et al. (2004), Spencer
& Steyskal
(1986), Felt (1917), Aldrich & Osten-Sacken (1905), Knight
(1941),
Watson (1928), Wheeler et al. (1983), Cranshaw (2004), Hottes &
Frison (1931), Blackman & Eastop (2013), Dennis (1952), Covell
(1984/2005), Miller (1987), and Vickery & Kevan (1985) for more
information. Vertebrate animals use goldenrods as a source of food to a
more limited extent. The seeds of these plants are eaten by such birds
as the Indigo Bunting, American Goldfinch, Slate-colored Junco, and
Tree Sparrow; the Greater Prairie Chicken feeds on the foliage and
flowerheads (DeVore et al., 2004; Martin et al., 1951/1961; Yeatter,
1943). Occasionally, the White-tailed Deer and Cottontail Rabbit also
feed on the young foliage of goldenrods (Sotala & Kirkpatrick,
1973; Martin et al., 1951/1961). These plants are a source of food for
the Prairie Vole (Cole & Batzli, 1979) and probably other voles.
Photographic Location:
The wildflower garden of the webmaster in Urbana, Illinois.
Comments:
Sometimes this species is called 'Downy Goldenrod.' There is some
variability in the width of leaves, presence of teeth on the leaves,
abundance of pubescence, and presence of glandular hairs on this
goldenrod across its range. Downy Ragged Goldenrod (Solidago
petiolaris) is easy to identify in Illinois because of the
recurved
phyllaries (floral bracts) of its flowerheads; this is the only
goldenrod within the state that has this characteristic, and it is rare
among goldenrods (Solidago spp.) elsewhere. One species with this
characteristic is Stout Goldenrod (Solidago squarrosa).
This latter
species is found primarily in northeastern United States. Stout
Goldenrod has larger lower leaves than Downy Ragged Goldenrod (Solidago
petiolaris), and its lower leaves have more teeth. Overall,
it is a less
hairy plant than Downy Ragged Goldenrod. The remaining goldenrod with
recurved phyllaries, Wright's Goldenrod (Solidago wrightii),
is difficult to distinguish from Downy Ragged Goldenrod. Because
Wright's
Goldenrod occurs some distance away in the southwestern area of the
United States, it won't be
considered any further.