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Description:

Cephalanthera austiniae is a perennial orchid commonly called the phantom orchid due to the pure white coloration of the stem and flowers, which is indicative of the absence of chlorophyll. The genus Cephalanthera is derived from the Greek words cephos, head and anthos, anther, which refers to the position of the anther above the stigma in the flower (Clark, 1976). The stem has leaf-like bracts and can exceed 38 cm. in height, and bear over 25 flowers each about 2 cm. across. The flowers are white, subsessile, three-lobed, and hinged towards the middle with golden-yellow marking on the lower lobe. They are slightly cupped in appearance since they do not open fully, and they give off a sweet scent which resembles vanilla. The plants have rhizomes with thick fibrous roots, and the fruit is a round capsule that starts out pure white like the rest of the plant and darkens quickly with age (Coleman, 1995).

Ecology:

Cephalanthera austiniae is a myco-heterotroph that derives all of its food through a parasitic relationship with mycorrhizal fungi. Phantom orchids depend on fungal strands that grow into their roots and they subsist on sugars processed by the fungus. This relationship between orchid and fungi is not “mutualistic” since the fungi apparently receive no benefit (Bruns et al., 1997); (Rasmussen, 1995); (Coleman, 1995).

Cephalanthera austiniae is insect pollinated. The column is simple, with no rostellum (a projection on the stigma), and the stigma is sticky so that when insects enter the flower and probe for nectar, they brush against the stigma and leave with pollen stuck to their bodies. Insects deposit the pollen in the next flower visited, effectively pollinating the plants. These plants tend to grow with many other species of orchids that have similar habitat needs. Cypripedium fasciculatum, Listera convallarioides, Platanthera dilatata, Calypso bulbosa, Goodyeara oblonifolia, and several species of Piperia are some of the orchids known to grow alongside Cephalanthera austiniae (Coleman, 1995).

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Creative Commons Attribution 3.0 (CC BY 3.0)

© Crystal Durbecq, Oregon State University

Source: BOT 323 Flowering Plants of the World, Oregon State University

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