American alumroot (Heuchera americana)

7 Photos

Summary

American alumroot (Heuchera americana) adds a unique foliage element to the woodland garden. The heart-shaped, 3-5” wide basal leaves are variable in color, though frequently green with maroon mottling. The small, yellow-green flowers are borne in airy panicles on 2’ tall stalks. Thriving in sun to part shade, this plant is drought tolerant and grows well in most soil types if they are well drained. This semi-evergreen perennial can be massed as a groundcover. Suitable for use in a shaded rock garden or as a color accent in the woodland border. Companion plants with pink, red or burgundy features contrast nicely to its mottled leaves. Zones 4-9.

American alumroot is the pollen host plant for the summer cellophane bee (Colletes aestivalis). Cellophane bees (Colletes spp.) are also called plasterer bees due to the method of smoothing the walls of their nest cells with secretions that dry into a plastic-like lining. Many cellophane bees are pollen specialists, and all are solitary nesters. Prior to the bee survey conducted at Mt. Cuba in 2019, this species had not been recorded in Delaware, and had not been observed in the Northeastern U.S. for decades. In the Eastern U.S., this species has only been documented collecting pollen from straight species H. americana and the cultivar ‘Garnet’. In the Midwestern U.S. it has been documented on H. richardsonii. The female bees often chase and body slam each other off the flowers, causing them to tumble to the ground.

Numerous Huechera cultivars and hybrids exist, and it can be difficult to determine whether a specimen is straight species H. americana when the source is unknown. While the leaves of H. americana exhibit varying degrees of silver markings and red venation, the base color is medium green. Cultivars and hybrids are typically selected/bred for unusual leaf colors including lime green, purple, and orange. In addition to leaf color and shape, the floral display can yield further identification clues. H. americana blooms in late spring (late May to mid June), showcasing small, yellowish-green blossoms that bear bright orange pollen. Cultivars and hybrids may bloom during different intervals, and often have flowers that are slightly larger and showier, in various shades of white or pink.

‘Garnet’ and ‘Dale’s Strain’ are two selections that are similar to H. americana in leaf/flower morphology and bloom time.

‘Garnet‘ (photos 5 & 6) was selected in 1984 from a variable group of colored-leaved Heuchera americana growing at Mt. Cuba Center. This cultivar was selected for its almost entirely maroon foliage throughout winter. The original selections were made by Marcie Weigelt with evaluation and final selection performed by Dr. Richard W. Lighty. ‘The cultivar was introduced in 1989. The flowers of this cultivar are typical of H. americana, with no visible morphological differences.

‘Dale’s Strain‘ (Photo 7) is a seed-propagated cultivar with silvery-blue foliage highlights. Selected by Dale Hendricks of North Creek Nurseries, this variety was discovered in the mountains of North Carolina.

More Details

Plant Type
perennial
Sun/Shade Conditions
full-to-partial-sun
Foliage Character
semi-evergreen
Soil Moisture
average
Flowering Period
late-spring-to-early-summer
Soil PH
adaptable
Flower Color
green, white, yellow
Summer Foliage Color
green
Fall Foliage Color
green
Other Common Names
coralbells, alumroot
Fruit/Seed Color
tan

Additional Information

Illinois Wildflowers, Missouri Botanical Garden, Lady Bird Johnson Wildflower Center