Orchid family (Orchidaceae)
Description: This perennial orchid is 1-2½' tall and unbranched. The central stem is light green, terete, glabrous, and somewhat stout. There are 2-5 alternate leaves along each stem, developing from sheaths. They are 2-8" long and ½–2" across, becoming smaller as they ascend the central stem. The light to medium green leaf blades are elliptic, elliptic-oblong, or lanceolate-oblong in shape and smooth along their margins; their veins are parallel. In relation to the stem, the leaf blades are nearly erect and slightly spreading. The central stem terminates in a narrow raceme flowers about 3-8" long. The whitish or yellowish green flowers are arranged all around the central stalk of the raceme on ascending stout pedicels about 1" long. At the base of each pedicel, there is a linear-lanceolate bract about ¾" long.
Each flower is about ¾" long and across, consisting of 3 petals, 3 sepals, a nectar spur, and reproductive organs. The upper sepal and upper 2 petals (about ¼" long) form a small hood (upper lip) over the reproductive organs and nectary opening. The upper sepal is broadly oblong in shape, while the upper 2 petals are linear to linear-oblong. The 2 lateral sepals (about ¼" long) are broadly oblong and usually curve backward from the front of the flower. The lower petal forms a lower lip that is deeply divided into 3 fan-shaped lobes. The lateral lobes and usually the central lobe are deeply fringed; less often, the central lobe is shallowly divided into 2-3 smaller lobes. The fringed lower lip may be more white than other parts of the flower. At the back of the flower, there is a narrowly cylindrical nectar spur about ¾" long that nods downward. The blooming period occurs during mid-summer and lasts about 3 weeks. The flowers are often fragrant, especially at night. Fertile flowers are replaced by narrowly ellipsoid seed capsules about ¾" long. The seed capsules split open to release numerous tiny seeds, which are distributed by the wind. The root system consists of fleshy fibrous roots. Sometimes, vegetative offsets develop a short distance from the mother plant.
Cultivation: The preference is full or partial sun, moist conditions, and an acidic soil containing sand, silt-loam, peaty material, or some gravel. Like other orchids, this species requires the appropriate endomycorrhizal fungus in the soil for proper growth and development. It can be difficult to transplant successfully.
Range & Habitat: The native Green-Fringed Orchid has been found in most areas of Illinois, particularly the NE section of the state; it is relatively uncommon. Habitats include moist prairies and sand prairies, sandy swamps, moist open woodlands, shrubby bogs, acidic gravelly seeps, low areas along streams, sandy fields, powerline clearances, and ditches. Green-Fringed Orchid is more likely to appear in degraded areas than many other orchids, although it also occurs in higher quality habitats.
Faunal Associations: The flowers are pollinated primarily by moths, including Noctuid moths and Sphinx moths. Such species as Anagrapha falcifera (Celery Looper Moth), Allagrapha aerea (Unspotted Looper Moth), and Hemaris thysbe (Hummingbird Clearwing) have been observed sucking nectar from the flowers. Mammalian herbivores (deer, rabbits, cattle, etc.) sometimes enjoy a gourmet meal by browsing on the foliage and flowers of this and other terrestrial orchids.
Photographic Location: A prairie in Fayette County, Illinois. The photograph of the flowering plant was taken by Keith & Patty Horn (Copyright © 2009).
Comments: Because of its greenish flowers, this orchid doesn't stand out from the background to the same extent as more colorful orchids in its genus. However, it has a delicate beauty that is peculiarly its own. While there are many orchids in the Midwest that have greenish flowers, this orchid is the only one with a deeply fringed lower lip. Compared to the similar Platanthera leucophaea (Prairie White-Fringed Orchid), the Green-Fringed Orchid has a lower lip with more narrow and insubstantial lobes (this applies particularly to the central lobe). Other species in this genus, e.g. Platanthera blephariglottis (White-Fringed Orchid) and Platanthera ciliaris (Orange-Fringed Orchid), have fringed lower lips that are not divided into major lobes. Thus, not only color, but also subtle differences in floral structure, are important in the identification of an orchid species in this interesting genus.