(leatherleaf)
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Photo of Chamaedaphne calyculata by Janelle Eklund
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Leatherleaf is a medium-sized shrub with white urn-shaped flower characteristic of the heath family (Ericaceae), common in low elevation wetlands and black spruce
muskeg in Denali, sometimes growing in standing water. Its
rhizomes grow deep in the mineral soil layer (
Pavek 1993). Leaves are thick and leathery (hence the common name), dark green above with white scales, and much lighter gray-green below. The leaves are alternate, pointing upwards from the stem. Leaves are
elliptic to
oblanceolate, minutely
toothed in the margin. Twigs are yellow-brown. The
inflorescences have several flowers in
linear racemes, held pendantly at the end of branches. The ends of the branches bend out horizontally. The white flowers are urn-shaped, constricted before the five small triangular lobes of the
corolla, 4.5-6 mm long. The fruits are rounded, brown, dry
capsules, 3-5 mm long, splitting open to release many seeds. No other shrub in Denali has white bell-flowers and leathery,
oblong leaves.
Leatherleaf flowers in early to late May, prior to most other plants opening their leaves (
Viereck and Little 2007). Its
capsules release their seeds in September (
Densmore 1997). In a trial in Ontario,
found leatherleaf to be the most cold-hardy of bog-dwelling ericaceous species, proposing that this is an adaptation to its early flowering season. Some flowers of the Ontario specimens were capable of withstanding -10 degrees Celsius. Leaves of
C. calyculata last a maximum of two seasons, and are shed steadily during the second summer (
Lems 1956,
Reader 1978).
Flowers produce nectar in order to attract insect pollinators, primarily bees, but also flies (
Hunter et al. 2000;
Reader 1977). Flowers contain both male and female parts, and can be self-fertile. Due to the bell shape of the flowers, undisturbed pollen falls to the ground, instead of onto the
stigma, and excluding insects reduces seed set (
Reader 1977). When pollinated, the flowers develop into a round, five-parted
capsule opening by a slit, containing 35-50 seeds. The seeds have a corky layer, which allows them to float and disperse via water (
Densmore 1997). In a study of seed germination of leatherleaf collected from Fairbanks, AK, the seeds germinated best when cold-stratified and exposed to long day lengths at temperatures of 20 degrees or fluctuating temperatures similar to natural conditions (
Densmore 1997). Sown in a natural environment, leatherleaf germinated in late May. The plant also spreads clonally, growing from
rhizomes, forming adventitious roots and clonal sprouts, often forming large clonal clumps (
Pavek 1993).
Chamaedaphne calyculata is an incompletely circumpolar species (circumboreal) occurring widely in the northern hemisphere except for is absent from Greenland. Leatherleaf occurs across the boreal region of North America in all Canadian provinces, and its range reaches south down the East Coast to South Carolina, and also throughout the upper Midwestern states. In Alaska, leatherleaf occurs in most of the boreal region, but is absent from Southeastern panhandle and the Aleutian chain (and western Alaska Peninsula). Leatherleaf occurs throughout the lowlands of Denali, where it is sometimes abundant, and it also occurs in boreal lowlands of Cook Inlet basin in the park south of the Alaska Range.
Details are shown in the Plots & Charts found at right, depicting recent Denali data.
Leatherleaf is a species of flat areas and low inclines. Its elevational range in Denali is 122 m to 743 m. It has the highest frequency and cover at less than 300 m. Cover decreases much faster than frequency as elevation increases. This species also shows a strong negative correlation with increasing slope, most specimens found on low inclines (beneath 4 degrees). This corresponds with this species habitat preference for wetlands.
Details are shown in the Plots & Charts found at right. For more on how to interpret these figures, visit Understanding Data Presented.
Poorly drained, wet sites.
