Description: This native perennial plant is about
2-3' tall and unbranched or sparingly branched. The central stem is glabrous
and 4-angled. Each pair of opposite leaves rotates 90° from the position of
the pair of leaves immediately below. For var. linifolia of White
Turtlehead, these leaves are less than ¾" across and
they are
linear-lanceolate in shape. However, the typical variety of White Turtlehead
has many leaves greater than ¾" and they are lanceolate or
lanceolate-ovate in shape. The leaves are hairless and serrated along their
margins. At the base, they are sessile, or have petioles that are less than
¼" in length. The central stem terminates in a dense spike of white
flowers, blooming from the bottom to the top. Each flower is about 1¼"
long, consisting of a 2-lipped white corolla, a green calyx with 5 oval teeth,
a slender white style, and 5 hairy stamens. Four of these stamens are fertile
and have anthers, while the remaining stamen is sterile and green. The tubular
corolla is somewhat flattened at the mouth, where it is more wide than tall.
The upper lip of the corolla functions at a protective hood, while the lower
lip has 2-3 shallow lobes and functions as a landing pad for visiting insects.
The lower interior of the corolla has abundant white hairs. At the base of the
calyx, there are a few green bracts that resemble the sepals. The blooming
period occurs from late summer to fall and lasts about 1½ months. There
is no noticeable floral scent. Each flower is replaced by an ovoid seed capsule
containing several seeds that are flattened and broadly winged; these seeds can
be blown about by the wind and probably float on water. The root system
consists of a taproot and rhizomes. Vegetative colonies may form as a result of
these rhizomes.
Cultivation: The
preference is full or partial sun, wet to moist conditions, and a fertile soil
containing some organic matter. Temporary flooding is tolerated. This plant can
be maintained in gardens if it is watered during dry spells.
Range & Habitat: White Turtlehead occurs
occasionally in central and northern Illinois, but it is rare in the southern
part of the state (see
Distribution
Map). The typical variety of this species is more abundant than var.
linifolia. Habitats include open woodlands in floodplain areas, thickets in
floodplain areas, wet prairies, sedge meadows, seeps, springs, marshes, and
fens. White Turtlehead is an indicator plant of fens, where the ground water
ranges from slightly acid to alkaline, but it occurs in other high quality
wetland habitats as well.
Faunal
Associations: The flowers are pollinated by bumblebees; sometimes
they also attract the Ruby-Throated Hummingbird. In central and northern
Illinois, White Turtlehead is the preferred host for the caterpillars of the
butterfly Euphydryas phaeton phaeton (Baltimore). This butterfly is
fairly uncommon. The foliage is bitter and usually avoided by the White-Tailed
Deer and other mammalian herbivores.
Photographic
Location: A moist area of prairie at Meadowbrook Park in Urbana,
Illinois. In the upper photograph, the plants with yellow flowers in the
background are Bidens polylepis.
Comments: The interesting flowers of this species
resemble the head of a turtle, hence the common name. Because of these unique
flowers, Chelone spp. (Turtleheads) are easy to distinguish from other
groups of plants. Among the Turtleheads occurring in the Midwest, White
Turtlehead is unique in having white flowers (although they are sometimes
tinted light pink or pale purple). It also has more narrow leaves than other
Turtleheads, which is especially pronounced in var. linifolia, as
illustrated in the lower photograph. The other Turtlehead that occurs in
Illinois, Chelone obliqua (Pink Turtlehead), has pink flowers and
broader leaves with longer petioles (these petioles exceed ¼" in
length). This species is uncommon and usually occurs in wooded habitats that
are more shady.