perennial wildflower is 2½-6' tall with a central stem that becomes
branched where the flowerheads occur. This stem is light green to dark
terete (round in cross-section), glabrous to sparsely covered with
short stiff hairs, and sometimes glaucous. Upper secondary stems have
similar characteristics. Pairs of widely spreading opposite leaves
occur along the central stem and any secondary stems; each pair of
leaves rotates 90° from the pair of leaves below. Leaf blades are 2-6"
long and ½-2" across; they are lanceolate-oblong to ovate-oblong in
shape, and either toothless or with widely spaced teeth along their
short-ciliate margins. The base of each leaf blade is rounded-truncate,
while its tip is long and gradually tapering. The upper surface of the
leaf blades is yellowish green to medium green and sparsely to
moderately covered with short stiff hairs, while the pale lower surface
is short-pubescent, especially along the major veins. Three
prominent veins join together at the base of each leaf blade. The
leaves are sessile or they have short ascending petioles (about 1/8"
The central and secondary stems terminate in flowerheads on
slender peduncles. Individual flowerheads are 1½-3" across, consisting
of 8-15 ray florets that surround numerous disk florets. The
yellow corollas of the ray florets are petal-like and widely
spreading.. The yellow corollas of the disk florets are narrowly
tubular (1/8" long or less) with 5 spreading lobes. At the base of each
flowerhead, there are light green phyllaries (floral bracts) that are
arranged in several overlapping series. Individual phyllaries are
linear-lanceolate and ciliate along their margins; the outer phyllaries
are widely spreading or recurved when the flowerheads bloom. The
peduncles of the flowerheads resemble the stems, except they are more
likely to have short stiff hairs. The blooming period occurs from
mid-summer to early fall for about 2 months. Afterwards, the disk
florets are replaced by achenes about 2 mm. long; these achenes are
ovoid-oblongoid and somewhat flattened. At the apex of each achene,
there is a pair of tiny chaffy scales that easily become detached. The
root system is long-rhizomatous. Vegetative colonies of plants are
often formed by the rhizomes.
The preference is full or partial sun, moist to dry-mesic conditions,
and soil that is loamy, sandy, or rocky. This wildflower is easy to
cultivate, although it may spread aggressively.
The native Woodland Sunflower is common in NE and
while in the rest of the state it is occasional.
Habitats include upland rocky woodlands, sandy woodlands, thinly wooded
bluffs, upland savannas and sandy savannas, woodland borders, sandy and
non-sandy thickets, limestone glades, hill prairies, and moist to
dry-mesic sand prairies. While this sunflower is normally found in
relatively dry upland habitats, sometimes it also occurs in moist
sandy habitats. Occasional wildfires tend to increase populations of
Woodland Sunflower as this reduces competition from woody vegetation.
The nectar and pollen of the flowers attract
variety of insects. The following bees are specialist pollinators
(oligoleges) of Woodland Sunflower and other sunflowers: Andrena
. Other floral visitors
include long-tongued bees (honeybees, bumblebees, digger bees,
leaf-cutting bees, cuckoo bees, etc.), short-tongued bees (Halictid
bees and Andrenid bees), miscellaneous wasps, miscellaneous flies
(Syrphid flies, bee flies, thick-headed flies, etc.), butterflies and
skippers, and Chauliognathus
(Goldenrod Soldier Beetle).
Other insects feed on the foliage, bore through the stems, suck plant
juices, etc., from sunflowers. These species
of the butterflies Chlosyne
(Silvery Checkerspot), Chlosyne
(Gorgon Checkerspot), and Vanessa cardui
(Painted Lady); the
caterpillars of Cochylis
(Banded Sunflower Moth), Papaipema
(Sunflower Borer Moth), Stiria rugifrons
Copper), and other moths also feed on these wildflowers (see Moth
). Sunflowers are important host plants for many aphids,
treehoppers, leafhoppers, plant bugs, leaf beetles, scarab beetles, the
larvae of weevils, the larvae of midges and other small
flies, grasshoppers, and other insects (see Insect
vertebrate animals use sunflowers as a food source. The seeds of these
wildflowers are eaten by the Hungarian Partridge, Bobwhite, Mourning
Dove, Eastern Goldfinch, Tufted Titmouse, Harris Sparrow, and many
other birds. Small mammals that occasionally eat the seeds include the
Gray Squirrel and other tree squirrels, Thirteen-Lined Ground Squirrel,
Meadow Vole, White-Footed Mouse, and Plains Pocket Gopher. This gopher
also feeds on the rhizomes of sunflowers in relatively dry sandy areas.
The Cottontail Rabbit browses on the foliage of seedlings and lower
leaves of mature plants, while the White-Tailed Deer occasionally
chomps off the stems and upper leaves of mature plants. Because the
Woodland Sunflower and other sunflowers are relatively tall and often
form dense colonies, they provide good ground cover for many kinds of
sand prairie at the Indiana Dunes National Lakeshore
in NW Indiana.
Woodland Sunflower is easily identified by its sessile, or nearly
sessile, opposite leaves. Other sunflowers (Helianthus spp.
longer petioles. Its stems are usually hairless or mostly hairless,
(Hairy Sunflower) and some other species in
this genus. Compared to some narrow-leaved sunflowers that occur in
prairies, the leaf bases of Woodland Sunflower are more broad and
nearly truncate. Some parasitic plants that occasionally attach their
haustoria (root-like extensions) to sunflowers and other species in the
Aster family include Cuscuta
(Rope Dodder) and other Cuscuta
(generally in moist areas that are often sandy), and Orobanche
(Prairie Broomrape) and other Orobanche spp.
dry areas that are often sandy). These parasitic plants can
significantly weaken the host plants to which they become attached.