- Yampah is a wild edible with good potential for domestication.
- The edible part of yampah is a carbohydrate-rich storage root, produced singly or in small clusters.
- Eleven species of yampah range from southwest Canada to the southwest US, with a disjunct population of a single species in the Midwest.
- Six species were commonly used for food by native Americans.
- Yampah roots taste a little like parsnip, but have a texture more similar to water chestnut.
- Harvestable roots are produced in about three years when growing from seed.
- Some species can be propagated from root offsets, which produce a harvestable root more quickly.
- Yampah will require a lot of breeding work to become a more popular crop.
The purpose of this guide is to provide information about growing, breeding, and using yampah in cultivation. While some of this information may be useful to foragers who are interested in collecting yampah, I am not providing any information about identifying species or differentiating them from poisonous species that are similar in appearance. Please consult a good foraging guide if you will be collecting yampah from the wild.
Yampah or yampa (Perideridia spp., previously Carum and Eulophus spp.), sometimes known as ipos (derived from the Spanish apio), indian potato, indian carrot, wild carrot, false caraway, wild caraway, or squaw root, is a native North American root crop that is comprised of twelve similar species. The majority of this guide refers only to the six species for which there is good evidence of historical use as an edible. The remaining species are described in the Relatives section at the end. Perideridia gairdneri (Gairdner’s yampah) is the largest and generally best known, with P. bolanderi (Bolander’s yampah) a close second in terms of yield, and P. oregana (Oregon yampah), P. kelloggii (Kellogg’s yampah), P. parishii (Parish’s yampah), and P. pringlei (adobe yampah) far behind in yield. Of these, I have only grown the first five. Of the questionably edible species, I have grown only P. lemmonii and P. howellii. Odds are that most of the information in this guide can be applied to any of the yampah species, but my experience ends with those.
Yampah belongs to the Apiaceae and so will have a very familiar architecture to anyone who has grown carrots, parsnips, skirret, root chervil, or many of the other edible and ornamental plants in that family. Underground, the plant forms usually two or three storage roots, but sometimes larger clusters. No species of yampah is high yielding in the way that you would expect of domesticated plants; storage roots of P. gairdneri and P. bolanderi may occasionally reach three inches in length, but more commonly about an inch. The other species that I have grown are much smaller. Still, this is an attractive plant for the breeder because the only trait in which it is lacking is size. It is tasty and nutritious; hardy; easy to grow (other than starting the seeds); safe, with a long history of human use; native to the Western US, with appropriate evolved pest resistances; and with abundant germplasm waiting to be collected (although this is often easier said than done). It is surprising that more effort has not been put into domesticating yampah.
The edible roots of yampah are storage roots or tuberous roots, not technically tubers, but they are so often referred to as tubers that I have probably slipped and included that term here somewhere. The roots are fascicled, which is a rather unusual feature in the Apiaceae. They are both edible and propagative, so you can eat the larger ones and replant the smaller ones. You can also cut off and replant the top of the storage root, eating only the lower part. This can be a useful technique when breeding. Cooked yampah has a flavor similar to parsnip but it is much less dense. It is also edible raw and has a crisp texture a bit like water chestnut, although the skin of the storage roots can be a bit woody. The grass-like leaves are also edible, although they are not very substantial and may become a little too tough to eat raw as the plants mature. The seeds can be used as a seasoning, similar to caraway; in fact, some yampah species were once classified in the genus Carum, the same as caraway.
The plant is perennial. It may flower as soon as the second year in good conditions, but it is not unusual for it to take longer, particularly in challenging conditions. Flowering may be intermittent, skipping one or more years before resuming (Baskin 1993). At flowering, the plants are usually two to three feet tall with umbels of white flowers. On occasion, plants grow significantly taller than that, reaching between four and five feet.
The following species have good evidence of past human use as edibles. While you can never declare any plant safe to eat for everyone, the roots of all of these species should be reasonably safe to eat and also the tops and seeds of some of them. See the chart under Cooking and Eating for more information about which parts of each species were used by native Americans.
Gairdner’s yampah (P. gairdnerii) is probably the most common and widespread yampah species and the one that is most commonly used as an edible. It is typically a tetraploid with n=19 or 20. There are reports of higher polyploid versions with n=40 or 60 (Chuang 1969), which would be octaploid or dodecaploid. Its natural ranges extends from southwest Canada to New Mexico, west of the Rockies. Its farthest eastern extent reaches across Montana and Wyoming into South Dakota. The tuberous roots may be as large as 3 inches by 3/4 of an inch, although they are generally less than half this size.
Bolander’s yampah (P. bolanderi) has nearly the same range as Gairdner’s yampah, but is less common. It is found primarily in California, Oregon, and Washington, but also reaches into Idaho, Nevada, Utah, and Wyoming. This is a tetraploid species with n=19. The storage roots are nearly the same size as those of P. gairdneri, just a bit shorter. Leaves are similar to carrot, although the leaflets are not as densely arranged. P. bolanderi traditionally has two subspecies, but Downie (2004) found that these subspecies are not closely related and suggested P. involucrata as a new species. P. bolanderi subsp. involucrata can be distinguished by having more thread-like leaves, reminiscent of dill.
Oregon yampah (P. oregana), sometimes also known as eppaw, is common in northern California, Oregon, and Washington. This is typically a diploid species with n=8, 9, 10, or 13. P. leptocarpa is thought to be a tetraploid of this species, so might be declared synonymous in the future. The storage roots are about half the size of those of Gairdner’s and Bolander’s yampah. The leaves of this species are variable, but more typically thread-like leaves with little branching in the leaflets.
Kellogg’s yampah (P. kelloggii) is native to central and northern California, from the coast to the Sierra-Nevada foothills. It is a tetraploid species with n=20. Unlike most species of yampah, it produces long roots in clusters of 5 to 25 (Chuang 1970) that sometimes bear a tuberous swelling toward the end. This makes it less attractive as an edible, but might well make it an attractive candidate for hybridization. Another reason that it might be useful for hybridization is that it has a pretty minimal stratification requirement compared to the species with better root size. P. howellii (which is probably closely related) has a similar root structure, but does not produce the occasional tuberous swellings of P. kelloggii. Leaves are somewhat similar to dill, although not quite as delicate.
Adobe yampah (P. pringlei) is a tetraploid (n=20) species of the central and southern coast of California, extending around the southern end of the San Joaquin Valley. Leaves thread-like and reminiscent of dill, although not as delicate. Very little is written about the size or quality of its roots and I have not grown this species.
Parish’s yampah (P. parishii) is mostly found in the Sierra-Nevada foothills in California, although it also sparser populations also reach into southern California and east into Nevada, Arizona, and New Mexico. Leaves are distinctive, short and relatively broad compared to other species, with fairly uniform leafets. A tetraploid species with n=19.
Yampah is primarily a meadow plant, growing in flat grassy areas with abundant spring moisture. In fact, the name yampah is adapted from the Paiute ya-pah, translated “water is here” (Trejo 1985). Most species are found west of the Rocky Mountains, from southern British Columbia to northern Mexico.
Yampah was once a very important edible for native Americans, but the introduction of grazing animals to the west greatly reduced the amount of suitable habitat. Some sources also suggest that plants were over-harvested by native Americans in some areas. Luther Burbank worked on this plant but, as with other minor edibles like rice root, none of his work seems to have survived. That may be an indication that breeding for improved yield is difficult, or merely that he couldn’t get people interested in eating yampah.
Settlement of the West has unfortunately had quite an impact on the distribution of yampah. Agriculture has overtaken many of the most suitable natural habitats for yampah. Early settlers of the Willamette Valley in Oregon reported large populations of P. oregana, but it is now rare in the valley and is found mostly in the mountains. Universities hold collections of P. gairdneri from Los Angeles and San Diego, but no collections have been reported much south of Bakersfield since the 1930s.
I have only found a nutritional analysis for P. gairdneri, but it is likely that other yampah species are similar. The results show that yampah is primarily a starchy root, but it does have significant amounts of Vitamin C and potassium. Although the amount of protein is modest, yampah has a protein score of 81 (vs 100 for chicken egg), which is very good for a root crop.
|Calories||350 / 100 g DW 2|
6.35% DW 1
6.21g / 100g DW 2
|Fat||1.61% DW 1|
|Carbs||79.25g / 100g DW 2|
|Sugar||16.19% DW 1|
|Starch||69.39% DW 1|
|Fiber||5.25% DW 1|
|Vit A||122 IU FW 1|
11.22 mg/100g FW 1
|P||0.26% DW 1|
|K||1.29% DW 1|
Yampah roots can be eaten raw or cooked. Raw, they are something like the texture of water chesnut with a little bit of parsnip flavor. Cooked, they take on a texture and flavor somewhere between potato and carrot. They can be boiled, roasted, or fried with good results. It is said that the raw root can act as a laxative in large amounts. I don’t know what is considered to be a large amount. I have never experienced any problems eating as much as a handful of raw yampah. That said, you might want to take it slow when snacking on the raw roots. I think that they are much better tasting when cooked anyway.
Native American Food Uses of Perideridia Species
|P. bolanderi||Storage roots||Atsugewi||Dried and used as a flour or rehydrated in soups|
|P. bolanderi||Storage roots||Miwok||Eaten raw; boiled and eaten like potatoes; sun dried for three or four days, then pounded to form meal (Barrett 1933)
|P. gairdneri||Storage roots||Blackfoot||Eaten raw; dried and used rehydrated in soups|
|P. gairdneri||Storage roots||Flathead||Smashed, formed into cakes, and dried|
|P. gairdneri||Storage roots||Okanagan||Eaten raw; cooked, dried, and mixed with dried deer meat; made into a pudding|
|P. gairdneri||Storage roots||Paiute||Cooked roots used as a mush or gravy|
|P. gairdneri||Seeds||Pomo||Used as an ingredient in pinole|
|P. gairdneri||Storage roots||Pomo||Eaten raw or cooked|
|P. gairdneri||Tops||Pomo, Yana||Eaten as a fresh green|
|P. gairdneri||Storage roots||Miwok||Roots eaten (Levy 1978)
|P. gairdneri||Storage roots||Umatilla, Ute||Roots crushed, chopped, formed into cakes, and dried (Hilty 1980)|
|P. kelloggii||Seeds||Mendocino||Used as a flavoring in pinole|
|P. kelloggii||Tops||Mendocino||Eaten as a fresh green|
|P. kelloggii||Storage roots||Mendocino||Eaten raw or cooked|
|P. kelloggii||Storage roots||Miwok||Roots eaten (Levy 1978)
|P. oregana||Storage roots||Klamath, Paiute||Dried and eaten raw|
|P. parishii||Storage roots||Yokut, Miwok, Mono||Roots eaten (Anderson 1996)|
|P. pringlei||Storage roots||Kawaiisu||Peeled, boiled and eaten like potatoes|
|P. pringlei||Storage roots||Yana||Roasted|
Moerman (1998) is the source for all information in this table unless otherwise noted.
Roots should not be kept out of the ground long and should be planted as soon as you receive them in most areas where the plant can be grown. The exception is very wet areas. Yampah roots tend to rot in very wet soil, so you can attempt to store them in slightly damp sand or in pots. I wouldn’t say that this works really well, but it does work better than storing them in wet ground.
Like many plants in the family Apiaceae, yampah seeds do not have a particularly long storage life. I haven’t done germination tests to get percentages, but I have observed that germination is very sparse in the second year after seed is collected. Storing seeds in the freezer will probably extend their life.
I recommend direct sowing yampah seeds in fall. This is a difficult seed to germinate and seedlings grow poorly indoors. In contrast, it is easy to start yampah seeds outdoors in all but the warmest climates in North America. As long as you experience temperatures of 40 degrees F or below for a good part of the winter, you should have no trouble germinating yampah.
Yampah has morphophysiological dormancy; in addition to requiring specific environmental conditions to germinate, the embryos are not fully developed at seed maturity and require several months at low temperatures to complete their development. If you can’t fall sow your yampah seeds, they will need 3 months of cold, moist stratification. Depending on the species and the accession, seeds may require longer stratification; Phillips (2003) found that seeds of P. gairdnerii collected in Utah required 4 to 5 months of stratification. Without at least three months of stratification, you should not expect any germination, even from large amounts of seed. A warm period is not required prior to cold stratification (Baskin 1993).
To stratify yampah seeds indoors, mix them with a little moist soil in a plastic bag and put it in the refrigerator. Try to time the stratification so that it ends when temperatures are between 60 and 70 degrees F. Following sufficient stratification either sow the seed directly or in pots. At temperatures of 60 to 70 F, the majority of the seeds should germinate in about three weeks. I often see some early germinators in the plastic bags in the refrigerator. This is generally a good sign that the seeds are ready to sow.
Seed germination can be boosted with various treatments. Phillips (2003) found that germination was highest when treating the seeds with 0.03mM (approximately 1 g / L) of gibberellic acid, giving 67.2% germination vs 46.6% for untreated seed. Pre-stratification treatment with potassium nitrate or ethephon also improved germination, but not nearly as much as GA3.
Improved varieties are replanted from roots. Propagation is slow due to the small number of propagative roots produced, but once you reach the desired population size, you can simply harvest all but one from each plant to maintain the population.
Yampah spacing can be fairly dense under cultivation, as little as four inches between plants. This requires regular watering. Yampah seems to do best with a drip system. You want the soil to be slightly moist at all times, but never soaking wet. Mulching helps. Avoid fertilizing or large amounts of organic matter in the soil. An annual amendment of compost or well rotted manure is sufficient. Under these conditions, you will get larger roots than you would typically find in the wild. If you are dry farming yampah, increase the spacing to 6 to 10 inches. Yampah should be grown in full sun. Root development is poor even in partial shade.
If sowing in pots, make sure the pots are at least eight inches deep. Yampah grows poorly in shallow pots. I’m not entirely sure of the reasons for this, since it generally does not produce a substantial tap root. It may be because taller pots keep the yampah roots above the wettest soil. The USDA uses 10 inch Cone-tainers to grow yampah seedlings. I tried this in 2017 and found it very convenient, so I will probably use this method exclusively in the future. Yampah seedlings don’t need much space and the Cone-tainers are very space efficient. That said, you don’t need to buy fancy new pots to grow yampah – any small pot will do. Germination appears to be best at temperatures of 60 F (15 C) during the day, with a nighttime temperature as low as 42 F (6 C) (Baskin 1993). First year plants may produce only cotyledons. In difficult climates, it may be preferable to grow yampah in pots for its first year, transplanting out the established, dormant roots in late fall or early winter. Do not transplant yampah when it is actively growing. The plants rarely survive the shock. Dormant plants transplant with a high rate of success in fall or early winter and an acceptable but slightly lower rate of success in spring.
Yampah has unusually slow development if you are accustomed to domesticated Apiaceae. The first year, yampah plants only grow for a few months and typically only form cotyledons. They then senesce, leaving behind a small root. These first year roots can be as small as a grain of rice and so you might think that the plants have just died. This is a good reason to grow yampah in pots the first year. The first year root produces a plant with true leaves in the following year. The second year plant will often go to seed, but not always, and rarely produces offset roots. In the third year, you get a fully mature plant that is capable of producing both seed and offset roots (depending on species). There is considerable variation in this pattern. Some plants produce true leaves the first year and some plants even flower the first year, but this is not common.
Cool temperatures are required for bud growth on Perideridia roots. This undoubtedly varies between species, but the only available information suggests that winter temperatures below 60 F (15 C) are required. This mostly limits yampah growing to temperate regions, although roots could be dug and chilled in a refrigerator before replanting in marginal climates.
One compelling reason to grow yampah in pots is in order to compress the first two years of growth, producing reproductively mature plants much more quickly. It takes only about three months to go from seedling to a first year storage root. The first year roots can then be refrigerated for two months and then placed outdoors or in a greenhouse, at which point they will resume growth. After 3 or 4 months, water should be withheld and the plants will go dormant again. The roots can then be planted out in their final locations over winter and many will flower the following year. This is another compelling reason to start yampah in space-efficient containers like Cone-tainers – you can put whole trays of Cone-tainers into a refrigerator for stratification.
Although it is a perennial, yampah completes its growth for the year by mid-summer, freeing up space for other plants. The only problem is that you don’t really want to disturb the roots. Shallow rooted plants like leafy greens might make a good secondary crop.
Unlike many perennial food plants that can be optionally grown as annuals, yampah is an obligate perennial. Even under ideal circumstances, it will take two years to develop roots that are worth harvesting as food. Given the difficulties of establishing new plants, I recommend planting yampah in a site where it will persist for many years.
If you live in a very wet climate (like ours), you should probably dig your yampah roots before the rainy season and store them under drier conditions. Moderate rainfall won’t cause any problems, but yampah roots tend to rot under our unrelenting fall and winter rains. I store them in bags of dry potting soil in the refrigerator and plant them out again in early spring.
Most species of yampah grow in environments that are wet in spring, but dry out as summer approaches. This means that yampah does most of its growing and completes its reproductive cycle in a short growing season. By the beginning of summer, yampah begins to flower and most of the foliage other than the inflorescence dries up and falls away. It appears that the period of active growth can be extended by providing regular water, but even in that case the plants go into full reproductive mode by mid-summer. Unsurprisingly, the roots are in best condition in late spring, before the plant has put energy into flowering. It might be possible to improve the size and quality of yampah roots by carrying out reproductive pruning.
Seed should be left to mature on the plant as long as possible. Seed size is strongly correlated with viability. Phillips (2003) found that seeds weighing 0.82mg had more than double the viability of seeds weighing 0.53mg and that seeds weighing 1.2mg had more than three times the viability. If rain is not a problem, covering the maturing umbels with paper bags is a good way to prevent losing seeds while waiting for them to finish maturing and drying.
We dig the yampah roots during the dormant season, around the middle of August and store them in sand at 38 degrees F. There are several reasons why this is a good idea. Yampah roots survive wet conditions about as well as dahlia tubers; they often survive, but some will rot, particularly in unusually wet years. Voles will also dig them enthusiastically during the winter when there is little else to eat. It is also easy to lose them, particularly if they are first year roots. If you have much weed cover appear during the winter, you might have a hard time finding the grass-like sprouts when they emerge in the spring.
All according to Moerman (1998): The Atsugewi dried the roots of P. bolanderi for winter storage. The dried roots could then be ground and used to make bread or rehydrated in soups. The Blackfoot, Cheyenne, Flathead, Okanagan, and Paiute used P. gairdneri in the same fashion. The Okanagan stored roots in pits for the winter (presumably not dried).
Yampah roots are fascicled; they have offset rootlets that can be detached and will sprout to form new plants. This is by far the easiest and fastest way to propagate yampah. The only problem is that not every plant forms these rootlets. I consider propagative rootlets a high priority for breeding, so I don’t mind disposing of the plants that don’t form them. You can also propagate yampah from stem cuttings taken before the plant flowers, but they take a very long time to root.
The yampah species that I have grown are all facultative outbreeders. They are capable of self-pollination, but seed set is poor. Seed set is much improved by crossing to other members of the same species and even to other members of the genus. I don’t know if this holds true for every plant in the genus.
As far as I can tell, P. gairderni, P. bolanderi, and P. oregana all hybridize easily. If you want to keep them pure, you will need to isolate them by typical distances for other Apiaceae like carrots (distance depends on climate and pollinator density). On the other hand, allowing them to cross pollinate appears to occasionally produce plants with larger roots, at least in the case of crosses between P. gairdneri and P. bolanderi. Large populations of crosses between Perideridia species are probably a good place to start with yampah breeding.
Grown in the Western United States, where it is native, yampah appears to be a relatively trouble free crop. I haven’t had much trouble with it anyway, aside from the usual suspects that damage root crops.
If you have read even one of our other growing guides, I’ll bet that you can guess the critter that gives us the most trouble with yampah: voles. Voles will happily dig up and eat all of your yampah. This is another good reason to dig up your yampah for overwintering, even if you live in a dry enough climate for it to survive the winter in situ. I am told that gophers may be an even greater scourge, but I don’t have first hand experience.
I have seen no obvious signs of disease in yampah yet.
Yampah roots can crack when they are exposed to heavy rain during the dormant season. The plants usually survive, but the eating quality of the roots is ruined.
Unlike most of the plants that I write about, yampah is undomesticated. It may have undergone some minimal domestication by native Americans, but we don’t have any particularly clear evidence for that and, in every way that matters, it behaves like a wild plant. The challenges of domesticating a wild plant greatly exceed those of breeding plants that have already been domesticated. The to-do list for yampah is very long. Root size is the most obvious trait in need of improvement. Some plants can produce edible roots the size of baby carrots at full maturity, but that is three or more years of growth. And most plants produce much smaller roots. There won’t be many farmers lining up to grow plants with such a puny yield. Root size isn’t really yampah’s most difficult feature though. Three or more years to full maturity is unacceptably long for a domesticated crop. The seedlings are small, delicate, and get lost easily without very good attention to weeding. The seeds require long stratification, have a relatively short lifespan, and mature too late for easy collection in wet climates. Species from coastal California, like P. californica and P. kelloggii, germinate with much less stratification and may be a good source of genetics for overcoming that problem in other species. All of these will need work for yampah to be a seed propagated crop, but that may not really be an option. Most yampah species are tetraploid and polyploid variability may impede the development of true breeding varieties. Luckily, yampah can be propagated from root offsets, which is likely to be the best method of propagation. This is particularly true since, as a wild crop, yampah is likely to be slow to respond to selection. The ability to propagate vegetatively from root offsets allows faster variety development. Unfortunately, less than half of the varieties that I have grown from seed have produced root offsets, so we also need to select for varieties that reliably produce them. Yampah will also probably benefit from selection for longer growing season. It is naturally adapted to wrap up its growing season fairly early to accommodate summer drought, but under cultivation it would be possible to keep it growing much longer. This would probably help in producing larger roots.
The wonderful thing about yampah, for growers in North America, is that yampah is a native crop, so it is much easier to collect germplasm than for almost any domesticated crop. (Very few crops were domesticated in North America, so our access to wild relatives of major crops is poor.) All species of yampah can be found in California and Oregon, so a few weeks spent collecting can yield a diverse collection of seeds to use as a starting population. I have gone on two yampah collecting trips with great results and I’m planning the largest trip yet for 2018 in the hope of finding some of the species that aren’t in our collection yet.
I’m not yet sure of the best approach to yampah breeding. There is basically no research available on the subject. I am going in several different directions until one course emerges as decidedly superior. The most obvious approach is mass cross and recurrent selection. I have been taking this approach with P. gairdneri, P. oregana, and P. bolanderi with some improvement in average root yield to show for it. However, I’m not sure that this species-specific approach is the best course. I have noticed that there appears to be very little barrier to crossing between species, at least between the three major species just mentioned. I am now starting a population of mixed species from which I will do recurrent selection. This will have the advantage of maximizing genetic diversity, although I expect that it will take longer to reselect for improved average yield. The other approach is to work with diploid accessions of P. oregana, which may allow the production of true breeding, seed propagated lines. This is still likely to be a long slog. I am first selecting for varieties with good root size to propagate vegetatively. When I have a large enough population of those, I will cross them and select from the next generation of seed. It will be interesting to see if there is any noticeable difference in the rate of development between the diploid and tetraploid populations.
It is impossible to guess what might result from a mass inter-species cross in Perideridia. At least some of the species can cross successfully. While tetraploids with sequential chromosome numbers probably cannot cross directly, it is plausible that the odd numbered species could cross, yielding even numbered hybrids that could cross to even numered species. This seems like a probable route by which speciation occurred in Perideridia. Chromosomal arrangements are surprisingly complex in the genus, with almost as many different chromosome complements as there are species. All but one variety (P. oregana) is tetraploid. P. oregana comprises a series of n=8,9,10, and possibly 13, forming a continuum of traits (Chuang 1969), while the polyploids are more distinct. Tetraploids are n=17,18,19,20,22. This, at the very least, suggests that allopolyploids exist at the tetraploid level, at least for the odd ploidies and probably others as well. Downie (2004) found some evidence for three different clades in North American Perideridia, with P. americana on its own (unsurprisingly), a second clade comprised of P. gairdneri, P. oregana, and P. leptocarpa, and the third containing all remaining species.
It might also be worth investigating higher polyploids in yampah produced through chromosome doubling. Chuang (1969) reported octaploid (n=40) and dodecaploid (n=60) wild collections. Many species have an optimum level of ploidy for certain traits and it is possible that higher polyploids could produce improved yield or other useful traits.
The following species are those that do not have any clear evidence of human use as edibles. That doesn’t mean that they are not edible though. Taxonomy is a modern invention and it is likely that native Americans recognized yampah using much broader criteria than we do. For example, the Shasta word ipos is used to describe more than one Perideridia species that the Shasta Indians used (Todt 1997). The various species of yampah have relatively low genetic diversity. Many foraging books refer simply to the genus Perideridia and I have never heard of anyone being poisoned by eating the wrong variety. I strongly suspect that all Perideridia species are safe to eat, but I don’t recommend that you test this.
Eastern yampah (P. americana), also known as wild dill (it is not a close relative of true dill), is the only yampah species found exclusively east of the Rocky Mountains, where it is found in greatest density in Missouri and Illinois (Chuang 1969). It is a tetraploid species with n=20 and likely descended from P. gairdneri subsp. borealis or from a common ancestor. In addition to having the same chromosome number, both P. americana and P. gairdneri subsp. borealis are the only species that produce flavones but not flavonols (Giannasi 1976), so there are multiple lines of evidence suggesting their close relationship. There is very little information to be found about edibility of this species. This may be because the roots are very small or it could be that the plant is not edible for other reasons. It may still be interesting for potential hybridization with other yampah species due to its different climate tolerance. Leaves are very reminiscent of carrot. For more information about eastern yampah, check out this great article from the Nomad Seed Project.
Mother lode yampah (P. bacigalupii) is an uncommon tetraploid (n=19) species from the Sierra-Nevada foothills in northern California. Leaves are thread-like and reminiscent of dill, although with sparser leaflets.
California yampah (P. californica) is a tetraploid (n=22) species found in both the coast range and Sierra-Nevada foothills in California. It is notable for having tuberous roots as much as five inches long, which is quite substantial for any species of yampah. Unusual leaves, with a long central leaflet and smaller serrated leaflets to each side.
Red rooted yampah (P. erythrorhiza) is a tetraploid species (n=19) forming three populations in Oregon. It differs from the other common yampah species in that its storage roots are sometimes a rusty red color and in having more and larger roots (Roberts 2003). Leaves have very long, thread-like leaflets. One source indicates that it is edible, but it is not a primary source (Todt 1998) and I haven’t found any others. It may be an attractive candidate for hybridization given its larger size. It also grows under the wettest conditions of any of the western yampah species, which is an attractive trait for our climate. I have not grown this species.
Howell’s yampah (P. howellii) is a fairly widespread tetraploid (n=20) species in northern California and southern Oregon. Unlike most other yampah species, it does not form substantially tuberous roots, forming instead a mass of thin storage roots. Because of this, it is probably not a promising edible species, but could still be valuable for breeding. The leaves are very similar to parsley leaves.
Lemmon’s yampah (P. lemmonii) is a tetraploid species (n=18 or 19) native to the three border region of eastern Oregon, northeast California, and northwest Nevada. Plants are smaller than most other yampah species and typically produce a single, small tuberous root. One of the less promising edible species, but that doesn’t mean that it might not have some value for breeding. Downie (2004) found that accessions of P. lemmonii did not group together in genetic analysis and most likely should be divided into two species, probably divided between the n=18 and n=19 groups.
Narrow-seeded yampah (P. leptocarpa) is a species from the Klamath Mountains in northern California. It is now considered most likely to be a tetraploid variant of P. oregana, so this species may no longer be valid. P. oregana contains all of the diploid numbers found in Perideridia, and P. leptocarpa is reported to have n=17, so it is most likely a hybrid of n=8 and n=9 variants of P. oregana. It also could be a nothospecies (hybrid) of P. oregana and another species, although there isn’t an obvious candidate for the other parent. The combination of n=13 P. oregana and a n=21 species could yield a n=17 hybrid, but n=21 is the one chromosome number that hasn’t been observed in the n=17 to n=22 range of tetraploid Perideridia.