Twinleaf is and erect native spring flowering perennial forb growing from 4 to 10 inches high on smooth reddish stems.
The leaves are basal on long stalks and are divided lengthwise into two distinct, but very slightly unequal, kidney shaped leaflets (hence "twinleaf") with rounded to pointed tips and usually with a small point where they join together. They are usually not toothed but may have shallow lobes. Leaves remain on the plant until Autumn. Young plants will only have one leaf.
The flowers are solitary, occurring on a leafless scape (the above ground section of the underground root). There are usually 8 elliptic to obovate white petals, wider close to the rounded tips. Stamens with yellow anthers are paired with the petals and the green ovary complex in the center is round and on a short stalk. There are 4 sepals which fall away early. Flowering finishes before the leaves are fully mature and the leaf stalks continue to increase in length after flowering to as high as 20 inches.
Seed: Mature flowers produce a capsule-like structure containing 10 to 25 reddish seeds that have a white fringed appendage at one end. The capsule splits open along a horizontal line creating a lid-like top from which the seeds disperse when the lid opens and the capsule bends downward. This capsule looks like a small vase with a pointed lid on top.
Seeds are difficult to start as they take 2 years to germinate in the soil. They require of cold, moist period followed by a warm, moist period, followed by another cold, moist period. Each period of at least 60 to 90 days. If seed is stored it must be kept moist.
Habitat: Twinleaf grows in the rich loamy soils of woodlands that have moderate moisture and flowers in the dappled light of spring before full tree leafout. It grows from underground rhizomes which do not produce offshoots.
Names: The genus, Jeffersonia, is named for the 3rd President of the U.S., Thomas Jefferson. This was an honorary designation due to his great interest in Botany and it was also his favorite wildflower. The species, diphylla, is from the two Greek words di for 'two' and phyllon for 'leaf' and meaning two leaves on the stem but here meaning two leaflets that 'look like' two leaves. There are only two species in the genus Jeffersonia the other being Jeffersonia W. Bartram known as Jeffersonia, which has similar characteristics to the present species but is Asian. The author names for the plant classification are: First to classify was '(L.)' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was updated by ‘Pers.’ which is for Christiaan Hendrik Persoon (1761-1836), South African born botanist, educated in Europe, maintained a large herbarium, published Synopsis Plantarum, describing 20,000 species, but best known for his work in the fungi.
Above: Twinleaf flowers from early May to late May depending on the season. The leaf stalks further lengthen after flowering. Flowers are solitary on a leafless scape - which is the aerial section of the underground stem.
Below: Mature flowers produce a capsule-like structure containing 10 to 25 reddish seeds that have a white fringed appendage at one end. The capsule splits open along a horizontal line creating a lid-like top from which the seeds disperse when the lid opens and the capsule bends downward. This capsule looks like a small vase with a pointed lid on top.
Notes: Twinleaf is not indigenous to the Garden. The first plants were added by Martha Crone in April 1957 when she planted 3 south of the Garden office. Plants were received from a Mr. Johnson at the University of Minnesota. Twinleaf is native only to the five counties at the very SE corner of Minnesota, and is currently on the "Special Concerns" list of the Minnesota Department of Natural Resources. In the wild it is only found in sheltered valleys of those counties. Per the DNR "A species is considered a species of special concern if, although the species is not endangered or threatened, it is extremely uncommon in Minnesota, or has unique or highly specific habitat requirements and deserves careful monitoring of its status." In neighboring Iowa, the plant is on the "Threatened List".
Minnesota is the northwestern edge of the plants range in North America. It is usually found from Wisconsin south to Alabama and east to the coast, but not up into New England. In Canada it is known only in Ontario where it is considered quite rare. Twinleaf is in the same family (Berberidaceae) as Blue Cohosh (Caulophyllum thalictroides) and Mayapple (Podophyllum peltatum, both of which are in the Garden.
Lore: There is a little literature on the use of the plant by native Americans medicinally but the origin of the alternate common name of Rheumatism root is obscure.
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.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"