Epipactis gigantea Douglas ex Hooker
The largest of the epipactis genus of terrestrial orchids, the Chatterbox Orchid, also known as a “Stream Orchid” and “Giant Helleborine”, can be found throughout the Western United States and in southern British Columbia. It can be found in moist soils around marshes, lakes, rivers and streams.
In bloom (March-August) the orchid forms a loose
raceme of up to 15 flowers that are greenish yellow with purple veining.
The lower “lip” (or, if you think the flower looks like a bird’s beak, the lower beak) flutters up and down when flies pollinate the flower, hence the common name, “chatterbox”.
Photos:
http://www.biosurvey.ou.edu/okwild/chatbox.html
http://www.mindbird.com/epipactis_gigantea.htm
http://www.europa-nursery.co.uk/orchidac.htm
Northern California variety with purple foliage:
http://www.dunngardens.org/summer/epipactis_gigantea_serpentine_night.html