This Saxifrage family plant grows in the Upland Garden along the path edges. American Alumroot is a perennial forb native to the U.S. (but not Minnesota) growing up to 3 feet in height on erect flowering stalks. Stems can be smooth or with short hair. Three varieties are accepted- see notes below. The plant in the Garden is considered to be one of those varieties - var. hirsuticaulis.
Leaves: There is a rosette of basal leaves at ground level that are roundly heart shaped and palmately lobed with 5 to 9 shallow rounded lobes, all together 3 to 5 inches wide. Leaves are absent on the flowering stalk. Leaf margins have very coarse teeth. The leaf underside may have the same short hair as does the leaf stalk which is typically longer than the blade, although the amount of hair on the leaf stalk and the type of hair is a defining identification key to the three varieties noted below.
Inflorescence: The flowers occur in branched clusters atop the tall stems.
Flowers are short, about 1/8 inch wide, on a short stalk that has hair, sometimes glandular as in the plant shown here. The shape of the flower hypanthium is roughly bell shaped and while basically green, there are yellow to pinkish to purplish tints when in full sun (depending on the variety). The hypanthium shape graduates into 5 pointed somewhat triangular sepals and the entire surface is hairy, glandular in plant shown here. There are also 5 smaller petals that are attached to the inside of the hypanthium and placed alternately to the sepals, but as they are smaller the sepals usually obscure them. There are 5 stamens placed opposite the sepals; these have greenish-yellow filaments and yellow to orange anthers; there are two styles, exserted beyond the stamens, which also tend to protrude from the throat of the flower. Yellow to orange nectary tissue is at the base of the styles.
Seed: Fertile flowers produce a dry seed capsule with two divergent beaks. The capsule contains dark brown ellipsoid shaped seeds. Seeds usually need 30 days of cold stratification and, because they are very small, light for germination.
Habitat: American Alumroot grows well in moist to dry soils with sun in the northern part of the range (like Minnesota) but in the more southern range it needs light shade during the warmer summer months. Heavy soils or very sandy soils are not ideal. The root system has a branched caudex and fibrous roots. Propagation is best done by dividing the root mass and replanting the caudex part at soil level. Seeds must be cold stratified for at least 6 weeks. Home gardeners will recognize these plant characteristics in the other Heuchera species known as coral bells, although in a much smaller scale.
Names: The genus name Heuchera is an honorary for Johann Heinrich von Heucher, (1677-1747), German professor of medicine and botany at Wittenberg and author of several books on botany. The species name americana, is in reference to America where this species is found. Heuchera is a world-wide genus. The author name for the original plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Varieties: There are 3 recognized varieties of the species: var. hirsuticaulis is considered an intergrade with H. richardsonii, the species native to Minnesota. Here the leaf stalks are dense with stipitate-glandular hair. Then there are two varieties where the leaf stalks are either without hair or with short to sparsely long stipitate-glandular hair. The first is var. americana where the leaf stalk hair is absent or very sparse, where the petals are greenish, white or pink with margins entire or finely toothed and narrower than the sepals. The second is var. hispida, which is considered an intergrade with H. pubescens, where the petals are more pink to purple with a fringe-like margin and the petals are wider than the sepals. The leaf stalks are either without hair or with very short stipitate-glandular hair. The Huecheras are a complex and large group, difficult for botanists to classify. Most are now used as ornamentals. Flora of North America (Ref. W7) has full details on description provided above.
Above: Leaves are entirely basal. This plant grows along Blazing Star Boulevard and has formed a large clump with numerous flower stems rising. Drawing of var. hirsuticaulis from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - A flower panicle before the flowers open and the branches are full extended. 2nd photo - A panicle branch fully extended with flower open. Note the fine hair.
Below: 1st photo - The small flowers have a green bell shaped hypanthium with color tints ranging from yellow to pinkish to purplish. The green sepals with pointed lobes are much wider than the petals. Stamens and styles are exserted. 2nd photo - Basal leaf example.
Below: Here you can see the much smaller green petals that are placed in between the sepals. Opposite each sepal is a stamen. The outside of the hypanthium in this example is glandular hairy. Not all the varieties of this species will look that way. The orangish color in the base of the hypanthium is the nectary tissue at the base of the styles.
Below: Many examples of this variety will have whitish hair on the stalks of the flower cluster (1st photo) on the stems (2nd photo) and on the leaf stalk and leaf undersides (3rd photo).
Below: The basal leaf clump
Notes: Alumroot is thought to be indigenous to the Garden as Eloise Butler noted it in her Garden Log as Heuchera americana on May 25, 1907. However, H. americana is not native to Minnesota, it's territory is normally south and east of Minnesota; the species native to Minnesota, H. richardsonii, (Richardson's Alumroot) is well distributed throughout the state and that is the only native species of Heuchera in Minnesota as far as records go at the University of Minnesota Herbarium. The two species are quite close in appearance and the distinguishing characteristics involve technical points about the hypanthium. Eloise could have easily been mistaken and the species was actually H. richardsonii.
However, Eloise first actually planted Heuchera americana in the Garden on May 16, 1913. She obtained plants from Kelsey’s Nursery in North Carolina, an area where H. richardsonii does not grow. Martha Crone noted it in bloom in 1939, planted it in 1945, '46, and '54 and listed it on her 1951 census. She did not list the scientific name of those planted. Former Gardener Cary George reported that he had planted the species in the Garden in 1987 without noting the scientific name, which is probably where the existing plants in the Upland Garden near station 41 come from and that plant appears to fit the description of the intergrade species H. americana var. hirsuticaulis.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"