Stemless Lady's-slipper has a leafless flowering stem (a scape) rising directly from the root, 6 to 20 inches high. The scape has very fine soft hairs.
Leaves number 2, are opposite, veined, and rise directly from the root. They are thick, broadly elliptic in shape, 8 to 12 inches long by 1 to 6 inches wide.
The inflorescence is a solitary flower atop the scape.
Flowers: Members of the genus Cypripedium have three petals and three sepals. These are the same color which can range from reddish brown to green in this species. Two sepals are joined together as to appear as one, forming the lower sepal. This joined sepal and the upper sepal form a lower and upper hood. Two petals are usually spread outward, slightly descending, usually spirally twisted and the same color as the sepals. The lower third petal forms an inflated lip, or pouch, or slipper, which ranges from white to magenta with darker veins. It can be up to 2.5 inches long. The inflated lip has a vertical fissure the length of the lip; the lip folds in along the fissure. The upper inside of the lip is crested with long white hair and on the scape there usually is a small green bract as seen in the photos below. The sexual parts are inside the pouch, somewhat hidden by a large somewhat triangular anther of a false stamen (a staminode). There is a real anther to either side. Bees entering the pouch through the fissure fine no nectar, but can't back out of the fissure due to the infolding, must finding their way out though a slit near the pollen bearing anthers. On the way in they may have put pollen they were carrying on the central stigma.
Seed: Pollination is usually by bees and fertile flowers produce an oblong-ellipsoid ribbed capsule containing many small dust-like seeds, but reproduction is normally via the root system. The capsule ribs have short hairs. Orchids are monocots and must take in a food supply from the environment. The Cypripedium seeds must be in contact with the Rhizoctonia fungus in the soil to germinate as the fungus helps the seed to take in nutrients.
Habitat: Stemless Lady's-slipper has a rhizomatous root system. It can be found in forest soils ranging from dry to wet, in bogs and heaths where the soil is acidic. Botanists say the the plants seem to prefer a slightly acid soil. Partial sun is preferred if the soils are more dry and sun in wet soils. From the wild they do not transplant very successfully due to a symbiotic relationship with a soil fungus and local laws may prohibit removing them from the wild.
Names: The former scientific name for this species was Cypripedium hirsutum but that is no longer accepted. The genus Cypripedium is derived from several Greek words that mean "Venus's shoe". The species name, acaule, is from the Latin acaulis, meaning "stem-less", referring to the plant not having a stem with leaves, but a scape, rising from the root.
The author name for the plant classification - ‘Aiton’ - refers to William Aiton (1731-1793), Scottish botanist, who succeeded Phillip Miller as superintendent of the Chelsea Physic Garden and then became director of Kew Gardens, where he published Hortus Kewensis, the Garden’s catalogue of plants.
Comparisons: This is the only Lady's-slipper with an entirely pink pouch. It is sometimes confused with the Showy Lady's-slipper), when the pouch is pink and white. The Stemless is usually finished blooming in central Minnesota before the Showy blooms.
Above: A solitary flower rises on a scape (an aerial stem rising from the root). Drawing 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 - The leaves are an opposite pair rising from the root. Some pairs of leaves will not have a flowering scape. 2nd photo - the scape rises well above the height of the leaves.
Above and Below: The front of the inflated lip forming the slipper has a vertical slit through which bees can enter but not exit. The two lateral reddish-brown petals are shown in the upper photo with a characteristic twist. In the photo below are seen the sepals of the same color - one reflexing downward behind the slipper, the other thrusting forward. Between them is a small green bract attached to the top of the scape.
Notes: Eloise Butler's records show that she obtained plants of this species right at the beginning when the Garden was established in 1907. The first ones were from within Glenwood Park (Now called Theodore Wirth Park). It was one of the first dozen plants she brought into the Garden as it was not present in the wetland at the time. Over the time of her tenure as Curator, she planted it in 18 of her 26 years. Curator Martha Crone also planted the species in nine different years, Ken Avery in 6 different years and Cary George once in 1989.
The species is not long lived in a transplant environment as this indicates. Soil conditions must be correct. The digging and transplanting of this genus is now generally prohibited by statute in Minnesota unless certain permissions are received. [18H.18 CONSERVATION OF CERTAIN WILDFLOWERS.]
For an article on both Lady's-slippers in the Garden and some history see Orchids in the Garden by Cary George in the Archive - Educational section.
Stemless Lady's-slipper is found throughout the part of the United States east of the Mississippi River excepting the Gulf Coast. Minnesota is the exception west of the River. In Canada it is reported in the lower provinces from Alberta eastward. Within Minnesota distribution is in the northern half of the state including the metro area counties of Anoka, Hennepin and Ramsey.
There are six Cypripediums found in Minnesota: C. reginae, Showy Lady-s-slipper; C. acaule, Stem-less Lady-slipper (or Moccasin flower); C x andrewsii, Andrews's Lady-slipper; C. arietinum, Ram's head Lady-slipper; C. candidum, White Lady's-slipper; and C. parviflorum, Greater Yellow Lady's-slipper in two varieties - var. makasin and var. pubescens.
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"