Calopogon tuberosus (L.) Britton, Sterns & Poggenb.
Family: Orchidaceae
Tuberous Grass-Pink,  more...
[Cathea pulchella ,  more]
Calopogon tuberosus image
Paul Rothrock  
Plants 4-110(-135) cm. Corms globose to elongate, not forked, 8-31 mm. Leaves not appressed to inflorescences at flowering; blade linear, lanceolate, or seldom elliptic-lanceolate, 2-50 cm × 2-35(-50) mm, margins slightly to strongly curled transversely. Inflorescences green or slightly purple at base, becoming entirely green after flowering, 4-135 cm; floral bracts ovate to ovate-lanceolate, subulate, 3-30 mm. Flowers 1-25, opening sequentially, magenta, pink, to white, faintly fragrant; dorsal sepal oblanceolate, 15-31 × 5-18 mm, apex acuminate; lateral sepals occasionally reflexed distally, ovate to lanceolate, slightly falcate, 13-26 × 5-16 mm, apex apiculate to acuminate; petals obpandurate to seldom elliptic, slightly falcate, 15-28 × 4-14 mm, apex obtuse; lip 11-23 mm, middle lobe with dilated end typically anvil-shaped, seldom triangular, 5.5-21 mm wide; column 12-25 × 1-2 mm, distal end 4.5-10 mm wide; rostellum present or absent; stigma at angle to column surface. Capsules ovoid to ellipsoid, 13-30 × 5-10 mm. 2n = 26, 40, 42. Calopogon tuberosus is the most variable and widespread species in the the genus. It occurs from Manitoba and Newfoundland south to Texas, Florida, the Bahamas, and Cuba. Calopogon tuberosus can be distinguished from other species in the genus where sympatric by its relatively robust size and elongated lip with wide, anvil-shaped dilated distal end. Plants with a triangular-shaped middle lip lobe are uncommon in the south and occur toward the northern part of the range, and those with long but narrowed lips occur in C. tuberosus var. simpsonii, the latter plants generally being much larger and occurring in a different habitat than all other species of Calopogon.

Perennial herb 10 - 80 cm tall Inflorescence: a single, erect, terminal, stalked, loose, spike-like cluster of three to fifteen stalked flowers with each flower subtended by a 3 - 8 mm long, egg-shaped bract with a long narrow tip. The faintly fragrant flowers tend to open sequentially rather than all at once. Flowers: light pink to bright magenta, under 7 cm wide, lacking a spur, bilaterally symmetric with central lip petal erect above lateral sepals and petals, and opposite central sepal. Between the upper positioned lip petal and lower central sepal an obvious, petal-like, winged column (fused reproductive parts of stamens, stigma and style) curves downward and forward. Sepals: three, spreading, petal-like, light pink to bright magenta, 1.3 - 3.1 cm long, 0.4 - 1.8 cm wide, egg-shaped with pointed tips. The two lateral sepals, which are positioned above the lateral petals, flare out sideways with reflexed tips, while the lower central sepal points downward or curves slightly forward. Petals: three, light pink to bright magenta, with central lip erect and nearly perpendicular to two lower petals, which flank the extended, petal-like column. The 1.2 - 2.3 cm long abnormal positioned lip (on other orchids typically below lateral petals) has two obscure lateral lobes near its base, a narrow central longer lobe covered with lines of distinctive yellow- or orange-tipped club-shaped bristles, and ends in a flared, anvil-shaped, 0.9 - 2 cm wide tip. Two lower lateral petals egg-lance-shaped to oblong, 1.4 - 2.6 cm long, 0.4 - 1.4 cm wide, facing slightly forward or slightly spreading with gradual upturned ends. Fruit: several, erect, more or less stalkless, 1.3 - 3 cm long, 0.5 - 1 cm wide, inversely egg-shaped capsules with three raised lengthwise ridges at the angles, and remnant parts of the column appearing as a hooked beak. Flowering stem: single, erect, sometimes slightly purple at base when young, hairless, lacking leaves, but with one to several tubular sheaths. This leafless structure terminated by flowers is called a scape and technically is not a true stem. Root system: of slender, white true roots attached to a 0.8 - 3.1 cm long, tuberous, rounded to elongate non-forked structure (corm, technically a shoot or stem). Leaf: usually one, basal, stalkless, grasslike, 10 - 50 cm long, 0.2 - 3.5 cm wide, linear to lance-shaped, ribbed, and slightly curled lengthwise. Column: petal-like, pointing down but curving forward, 1.2 - 2.5 cm long, 1 - 2 mm wide before greatly expanded (0.6 - 1 cm wide) tip. The obvious nature of the column allows for easy view of the stigma, which tends to be at an angle to the column surface rather than flat against it.

Similar species: There are two varieties of Calopogon tuberosus, but only the typical variety (as described above) occurs in the Chicago Region with the other variety, C. tuberosus var. simpsonii, restricted to very southern Florida, the Bahamas, and Cuba. At least historically, another species, C. oklahomensis, also existed in the Chicago Region. This species can be distinguished by its elongate and forked corms, the simultaneous opening of all flowers, the expanded tip of the central lobe of the flower lip being longer than wide and more triangular, and the stigma typically positioned flat against the column. Calopogon tuberosus often grows with and may be confused with Pogonia ophioglossoides, but that species has a single egg-shaped to elliptic leaf in the lower half of the stem, only a single flower at the top of the stem, and like other orchids in the area, the lip positioned on the bottom of the flower.

Flowering: early June to August

Habitat and ecology: Not common, in the Chicago Region most frequently found in peaty meadows, but also in open, sunny sphagnum bogs, and even marly fens.

Occurence in the Chicago region: native

Notes: All other orchid genera of the Chicago Region have flowers that are twisted 180 degrees (resupinate) such that the lip is on the bottom of the flower. Since Calopogon flowers are not twisted (non-resupinate), the lip is positioned at the top of the flower, and accordingly pollination differs from other orchid genera. In Calopogon insects are drawn to the club-shaped bristles of the lip presuming pollen is attached, but when the insect grabs onto the lip from below, the lip is unable to support its weight and then bends downward where the backside of the insect hits into the column. The insect's back is then loaded with true, individual pollen grains (instead of packaged pollinia) and thus transports pollen to the stigma of the next flower (Homoya 1993). According to Case (1987), Calopogon tuberosus may become quite abundant in habitats that are favorable since it reproduces easily both by seed and asexually by corms.

Etymology: Calopogon is derived from the Greek words kalos, meaning beautiful, and pogon, meaning beard, thus the "beautiful beard" refers to the bristle-covered lip. Tuberosus means tuberous, in reference to the tuberous corm.

Author: The Field Museum

Lf linear, to 5 dm נ4 cm, long-sheathing; scape 3-7 dm, with a loose raceme of 3-15 fls; tep rose-purple, 15-25 mm, acute; lip 15-20 mm, with a narrow basal part, the summit broadly flabellate, rose purple, crested on its face with stout hairs tipped with magenta and yellow; winged terminal portion of the column suborbicular (when flattened out), with tapering base. Acid bogs and swamps; Nf. to Minn. and se. Man. s. to Fla., Tex. and Cuba. June, July. (C. pulchellus; Limodorum t.)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
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Morton Arboretum  
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