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Bolander's yampah

Scientific Name:
Perideridia bolanderi
Native Name(s):
  1. Northern Paiute: yampah (Couture et al 1986); yapa (Couture et al. 1986); payapa (Couture et al. 1986); suiyapa (Couture et al. 1986); yapa (Fowler 1989); kazu (Fowler 1989); yapah (Fowler 1989)
  2. Pit River: pEtsku (Garth 1953); paha (Kniffen 1928)


Perideridia bolanderi emanates from tuberous roots that grow in clusters of 2 to 3. Basal blades are divided 1 to 2 times pinnately into toothed lobes.  Peduncles grow up to 20 cm with 4 to 10 bractlets and 9 to 23 white ray flowers. Fruits are generally oblong with thread-like ribs and are 4 to 6 mm in length. This species blooms from May to August.

Identification Tips

Perideridia bolanderi can be distinguished from other species of Perideridia by its toothed basal lobes. Whereas Perideridia gardineri has narrow, subdivided lobes and Perideridia oregana has linear to oblong leaflets.

Starch granules

Perideridia spp. storage starch granules are trimodal in size, ranging from 3-33 microns with an average size of 11 microns. Heteromorphic shape distribution; diads, triads and fours common. Many grains have central fissures, with ‘Y’ and ‘X’ markings most common. Irregular reniform grains have mesial longitudinal clefts. Cross is bright with symmetrical to wavy arms of a thin to medium thickness.


Perideridia bolanderi grows in many habitats including meadows, subalpine and alpine forests at elevations between 600 to 2000 m.


This species grows throughout the western United States in California, Nevada, Utah, Oregon, Idaho and Wyoming.


Yampah is an important food resource for many native populations. Digging sticks are used to harvest yampah roots in the spring, and may be consumed raw, roasted, or dried for storage over the winter months. 

As food

Northern Paiute: "Other prefer to dig Bolander's yampah.  Because of the long and fragile attachment of the bulb, the difficulty in digging yampah increases later in the season.  The yield of yampah for time and energy expended in gathering is relatively low.  However, according to nutritional analyses, it is a resource high in dietary mineral values." (Couture et al. 1986:156-157)

Northern Paiute: "The spring plant collecting area was a highly significant part of the larger seasonal round.  At specific sites, the roots of various species were collected.  These included sego lily, bitterroot, yampah, wild onion, biscuitroot, and several species of lomatium.  Desert celery and mint leaves also were collected for food.  Medicinal plants collected for their leaves included sagebrush, yarrow, and showy penstemon.  Juniper berries were used medicinally.  Paiute consultants were aware of the poisonous properties of larkspur and death camas." (Couture et al. 1986:154)

Northern Paiute: "From early spring well into summer root gathering was an economic activity of great importance.  Women went each day to dig ya'pa', tu˙nu'˙yu, mu'˙a', hu'˙nibui, pa˙si'go', and other roots.  These they prepared by boiling or by pit-roasting, or sometimes preserved by drying in the sun." (Kelly 1932:100-101)

Northern Paiute: "Roots of various members of the parsley family figured prominently in Paviotso diet, particularly ya'pa', commonly known as epos.  Quantities were gathered from the hills east of Surprise, and from the flats near Bear ranch in the south end of the valley.  The roots were rubbed on an open twine tray to divest them of their skins and were subsequently prepared in a variety of ways.  They might be eaten immediately, raw or boiled, or else dried in the sun and stored.  Dried ya'pa' was boiled and sometimes pounded." (Kelly 1932:101)

Northern Paiute: "Early in spring, when the snow was still on the ground, they fished in the creeks and streams.  As soon as the snow melted sufficiently, those camped in Surprise abandoned their winter quarters and crossed to the hills along the east side of the valley, stringing from Cowhead lake south to Poison spring, there to consume food buried the previous year and to dig whatever roots they could find.  All spring and well into summer they continued to wander about, gathering roots which they dried and cached for future use.  Their wanderings did not follow any set scheme; they roamed wherever the food supply seemed most promising.  A considerable range was necessary, however, for roots such as camas are essentially swamp plants, and other such as epos occur only in higher and drier country." (Kelly 1932:76)

Northern Paiute: "yapa is like a sweet potato, about as thick as the forefinger.  It is found in yellow clay and adobe in the canyons.  It is either eaten raw, boiled or roasted.  When it is roasted, it is covered with hot ashes." (Fowler 1989:43)

Northern Paiute: "yapa is dried and pounded and ground on the metate and they make a soup or mush of it by boiling.  It may be eaten raw when it is fresh.  The skin is peeled off the potato.  It is roasted in the hot sand." (Fowler 1989:43)

Pit River: "Epos roots (pEtsku, Perideridia bolanderi) were one of the staple foods.  They were plentiful east of Hat Creek on Murken Bench and around Government Lake, but especially so in Dixie Valley, where they are still abundant.  The roots were placed in a shallow basket (kopwar) with damp sand and worked back and forth  with the feet until the skins came off.  They were then dried on large flat rocks, being turned over now and then.  If rained on, drying roots would mildew.  Dried roots were stored for the winter.  When used, they were pounded in a basket hopper and made into either a soup or bread.  Bread was sometimes wrapped in grass, hung up to dry, and then stored.  Fresh roots had a fine meaty flavor and might be ground with the mano-metate.  Cleaned dry roots were Betiu; pounded dry roots, cetake; pounded green roots, hoh'caki." (Garth 1953:138)

Modoc: "The chief vegetable food of the Modoc seems to have been tubers and bulbs, notably camass and ipos." (Barrett 1910: 243)

Distribution Map: