Dune
Goldenrod
Solidago
simplex gillmanii
Aster family (Asteraceae)
Description:
This perennial wildflower consists of
a semi-evergreen rosette of basal
leaves from late fall to early spring, after which it develops a tuft
of unbranched stems that have alternate leaves below and
inflorescences above. During this latter period of active growth, Dune
Goldenrod becomes ¾-2½' long with erect to ascending stems. The central
stem of each plant is reddish green, terete, and rather narrow; there
are usually fine hairs that are arranged in lines toward the apex,
while toward the bottom the stem becomes glabrous. The lower
cauline leaves are 3-6" long and ½-1" across; they are medium green,
elliptic-oblanceolate in shape, hairless, and often sharply serrated
along their margins. The upper cauline leaves are 1-3½" long and ¼-½"
across (or sometimes less wide); they are medium green, narrowly
elliptic in shape, hairless, and usually smooth along their margins.
Both the lower and upper cauline leaves are ascending. The lower
cauline leaves taper gradually to petiole-like bases, while the upper
cauline leaves are sessile. The basal leaves are similar to the cauline
leaves, except they are somewhat wider.
The
central stem terminates in a narrow panicle of flowerheads about 3-10"
long and 1-2½" across. In each panicle, the flowerheads bloom from top
to bottom. The panicle is sparingly branched; the branches and
peduncles of the panicle are light green, narrowly terete, and often
slightly pubescent and resinous. Small leafy bracts (up to 1" long
& 1/8" across) occur along the branches of the panicle,
including
the central axis. The flowerheads have relatively long
peduncles (¼-½ in length) that equal or exceed the length of individual
flowerheads. Each flowerhead is about 1/6" (4-5 mm.) across and 1/4" (7
mm.) long, consisting of 7-10 yellow ray florets and slightly more disk
florets that are golden yellow. Each disk floret consists of a narrow
tubular corolla with 5 spreading lobes. Both ray and disk florets are
fertile and capable of producing achenes. The base of each flowerhead
has narrow floral bracts (phyllaries) in 2-3 overlapping series; they
are light green or pale yellowish green, more or less oblong
in
shape, hairless, and slightly resinous. The blooming period occurs from
mid-summer to early fall and lasts about 1-2 months. During the fall,
the florets are replaced by small bullet-shaped achenes (2-3 mm. in
length) with small tufts of hair; the achenes are sparsely to
moderately hairy. They are distributed by the wind. The root system
consists of a small caudex with fibrous roots and short rhizomes.
Vegetative offsets are occasionally formed.
Cultivation:
The preference is full sun, mesic to dry conditions, and
very sandy soil. Rocky soil is also tolerated.
Range
& Habitat: According to available records at
herbariums, Dune
Goldenrod does not occur in Illinois. However, it has been found in all
three counties of Indiana that border Lake Michigan, where it is listed
as a 'threatened' plant. Because it can be found across the state
border in Indiana, it is possible that Dune Goldenrod exists, or at one
time existed, as a rare plant in Illinois along the Lake Michigan
shoreline. Outside of the state, habitats consist of sand dunes, drier
areas of beaches, and rocky shorelines along Lake Michigan and Lake
Huron. This wildflower is usually found on semi-stabilized sand dunes
that are several hundred feet away from the lake shoreline; it can be
located on the lower slope, upper slope, or the flattened top of a
dune, usually in proximity to Beach Grass (Ammophila breviligulata).
Faunal
Associations: The following information applies to Solidago spp.
(goldenrods) in general as very little floral-faunal information is
available about Dune Goldenrod specifically. The flowerheads are
visited by a wide variety of insects, including long-tongued bees,
short-tongued bees, wasps, flies, small- to medium-sized butterflies,
and beetles. Several Andrenid bees (Andrena
spp.) and a Plasterer bee
(Colletes simulans armata)
are oligolectic visitors of the flowerheads:
their larvae require goldenrod pollen for proper growth and
development. Other insects feed on the plant or flower tissues of
goldenrods;
these species include the caterpillars of Schinia nundina
(Goldenrod
Flower Moth) and many other moths, several species of aphids
(mostly Uroleucon spp.),
the leafhoppers Neokolla
hieroglyphica and
Scaphytopius acutus,
the treehopper Campylenchia
latipes,
Corythucha
marmorata (Chrysanthemum Lace Bug), Homaemus
aeneifrons aeneifrons and other stink bugs, Lopidea media
(Goldenrod
Plant Bug) and other plant bugs, several leaf beetles (Microrhopala
spp., Ophraella
spp., Trirhabda
spp., & others), Eurosta
solidaginis (Goldenrod Gall Fly),
and grasshoppers that consume broad-leaved plants. Among vertebrate
animals, the seeds are eaten by the Eastern
Goldfinch, Pine Siskin, and other songbirds, while the leaves
and flowerheads are eaten by the Greater Prairie Chicken. White-Tailed
Deer
and Cottontail Rabbits feed on the foliage of goldenrods occasionally.
Photographic
Location: The upper slope of a large sand dune near Lake
Michigan at Indiana Dunes State Park in NW Indiana.
Comments:
This interesting goldenrod is one
variety of a highly variable species,
Solidago simplex,
which has a total of about 8 varieties that are
currently recognized. Most of these varieties, like Dune Goldenrod, are
habitat specialists with restricted ranges. Therefore, Dune Goldenrod
is the only variety that one is likely to encounter in Illinois or one
of the neighboring states. Another species, Solidago speciosa
(Showy
Goldenrod), can be found in sandy savannas and stabilized foredunes
near Lake Michigan, and it is possible to confuse depauperate specimens
of this species with Dune Goldenrod. However, Showy Goldenrod has a
more branched panicle with shorter peduncles, its cauline leaves vary
less in size as they ascend the central stem, and its achenes are
hairless. Another species, Solidago
uliginosa
(Bog Goldenrod),
also has an appearance that is similar to Dune Goldenrod, but
it inhabits wetlands. Bog Goldenrod has fewer leaves along its stems
and its floral bracts (phyllaries) are
yellow, rather than green or yellowish green. Other scientific names of
Dune
Goldenrod include
the following: Solidago
racemosa
gillmanii, Solidago
spathulata gillmanii, Solidago
gillmanii,
and
Solidago deamii.