''Platanthera ephemerantha'' is a species of

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Eart ...

known by the common names whiteflower rein orchid, slender white piperia, and white-flowered piperia. It is native to western North America from

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

to the

San Francisco Bay Area The San Francisco Bay Area, commonly known as the Bay Area, is a List of regions of California, region of California surrounding and including San Francisco Bay, and anchored by the cities of Oakland, San Francisco, and San Jose, California, S ...

, where it grows in

coniferous forests Conifers () are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All e ...

and other habitat in coastal and inland mountain ranges within 150 kilometers of the coast. It grows erect to about half a meter in maximum height from a bulbous

caudex A caudex (: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.pages 456 and 695 In the strict sense of the term, meaning a stem, "caudex" is most ...

. The basal leaves are up to 18 centimeters long by 3 wide. Leaves higher on the stem are much reduced. The upper part of the stem is a spikelike

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

of up to 100 small flowers, mostly arranged along one side of the stem. The fragrant, honey-scented flowers are whiter than those of other ''

Platanthera The genus ''Platanthera'' belongs to the subfamily Orchidoideae of the family Orchidaceae, and comprises about 150 species of orchids. The members of this genus, known as the butterfly orchids or fringed orchids, were previously included in the ...

'', but sometimes green-tinged or -veined, or green with white margins. The status of this species in the wild is difficult to determine because most populations are small and may produce flowers only rarely.California Native Plant Society Rare Plant Profile
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References

External links

Jepson Manual Treatment

USDA Plants Profile

Flora of North America

Photo gallery
ephemerantha Orchids of California Orchids of Canada Orchids of the United States Flora of the West Coast of the United States Flora of Alaska Flora of the Klamath Mountains Natural history of the California Coast Ranges Natural history of the San Francisco Bay Area Plants described in 1990 Flora without expected TNC conservation status {{Orchidoideae-stub