Sunday, March 27, 2016

Plant Story--Deathcamas

Deathcamas. It is a name to put you off from the start.

Yet it has a beautiful flower!

Zigadenus venenosus meadow deathcamas
Zigadenus venenosus meadow deathcamas
Pretty isn't it?
The deathcamases are found all over North America (USDA page) but especially in the west. The species in my photos, Zigadenus venenosus, meadow deathcamas, grows all over western North America (link).


The botanical names of deathcamas are very confused. I will call it Zigadenus. It is in the plant family Melanthiaceae, the false hellebore and trillium family. That is one of many plant families separated out of the once-huge lily family (Liliaceae), so if you don't know false hellebore or trillium (Trillium), think lilies (lily images) when imagining deathcamas.

The name deathcamas is based on the unrelated but somewhat similar-looking camas (Camissia species, asparagus family, Asparagaceae). The camases were important food plants of Native Americans in the Far West. In flower, blue camas has blue flowers and deathcamas flowers are cream-colored, so they are easily told apart. Generally Native Americans dug camas bulbs in the fall for winter storage (more detail), long after the flowers were gone. Deathcamases have bulbs similar enough to blue camas that anyone collecting blue camas had to be very careful to learn the difference. Deathcamas is poisonous enough that a mistake can make you very sick. So settlers got the name deathcamas as the plant not to confuse with the edible camas.

Zigadenus venenosus meadow deathcamas
deathcamas
Deathcamas poisoning symptoms include drooling, vomiting, decreased blood pressure and diarrhea. Most plant poisoning, deathcamas included, has successively worse symptoms depending on the amount of material ingested. At a high enough dose of deathcamas, the victim has seizures, lapses into a coma and dies. Deathcamas indeed.

Poisoning of livestock by deathcamas occurs most springs in western North American rangeland.

Reports of human poisoning by deathcamas are rare. As far as I can tell, they appear in the medical literature about once every five years, for the whole United States. It could be because people know their plants. We certainly warn about deathcamas. Or perhaps it is because so few people gather wild vegetables. Human deaths from deathcamas poisoning are known in the settlement-era literature but not during the last century. But if you eat a serving of it you will spend several very unpleasant days in the hospital.

In Colorado, blue camas does not occur (USDA map) so deathcamas is a risk not to people gathering blue camas but to people gathering other edible plants, in particular wild onions (Allium species, amaryllis family, Amaryllidaceae). Wild onions all smell like onion. If it smells like an onion, it is safe to eat. In flower, wild onions are easy to tell from deathcamas.

prairie wild onion, Allium textile
prairie wild onion, Allium textile
The problem is that if you've been gathering onions, your hands and bag will all smell like onions. If you pick a deathcamas plant, it does not smell of onions. But how can you tell against all the onion smell? Furthermore, if you are gathering for food, you won't just gather the plants with flowers, but also those without flowers. Wild onions are much harder to separate from deathcamas when not flowering. They often grow in the same places.

?
Alas, the prudent conclusion is to buy your onions and leave the wild ones alone!

Farther west, people have mistaken deathcamas for sego lilies (Calochortus species), including six people hospitalized in Utah in 2009. Members of a small distinctive family, the Calochortaceae, sego lilies share the simple, graceful structure of many lily relatives, including deathcamas. An important food of Natiave Americans and early settlers in the West, the foraging books that recommend gathering sego lilies don't warn strongly about deathcamas. Generally such books are careful, so I presume there are good characters to separate them. (Lacking sego lilies here, I can't easily test it for myself). However when I looked at the Colorado Flora for western Colorado, it seemed to me that most of the characters distinguishing sego lilies and deathcamas were flower characters, which would be a problem if you were gathering bulbs before or after they flower.

sego lily, California grasslands
sego lily portrait, from long ago in California
Since deathcamases have a wide range, all across North America be very careful gathering lily-like plants with bulbs to eat.

Toxins in the Life of Deathcamas: Deathcamas is a handsome plant and a conspicuous one. It doesn't receive a lot of scientific attention, but there are some intriguing studies.

Researchers have shown that if the leaves of deathcamas are grazed just before it flowers, the plant does not grow new leaves that year. The flower stalk continues to develop but no flowers mature. As an early grassland plant which is tall enough to be quite visible, getting eaten by hungry animals is a serious risk to the plant. It seems reasonable that filling its tissues with toxins to deter animals from eating the leaves is important to its survival.

The alkaloids of deathcamas that are so toxic are also bitter, so an animal need not eat very much to be warned off. Nevertheless, deathcamas kills a few cows and sheep every spring. Curiously, mule deer graze it and are not poisoned. Mule deer are native to the places deathcamas grows and normally feed on a great variety of plants, but it still surprised the researchers. Watching for four years in Utah, they noted that the mule deer bit the leaf tips off of some plants and devoured only a very few plants within big patches of deathcamas. They concluded that the leaf tips were a good place to taste for the toxic alkaloids and if the particular plant didn't have many alkaloids--and plants vary in poison content, just like people vary in height--then the deer ate the plant. The researchers saw no indication that mule deer, picky eaters that they were, were poisoned by deathcamas.


Deathcamas's toxins occur throughout the plant, including in the pollen and nectar. Pollen of deathcamas species is toxic to honeybees and to a native bee (Osmia lignaria). Doubtless other insects feed on it at their peril as well. The result is that most of the pollination is done by syrphid flies and a particular native bee (Andrena astragali, photos of similar bees: andrenid bee). Compared to other plants flowering at the same time, very few insects visit deathcamas. Deathcamas plants are obligate outcrossers: pollen must be carried to a different plant for fertilization and seed production. With few visitors, seed production in deathcamases is often poor.

You end up with an interesting picture. Since it grows early and can't regrow, being very toxic is important for deathcamas survival. Without the toxins, mule deer would eat even more plants. But the poisons affect the insects that transfer pollen between plants and the decreased number of pollinating insects reduces seed production. Some seed is produced, of course, because some insects can carry deathcamas pollen. Nevertheless, the solution to one problem was itself a problem, which is a good general observation about natural systems: every organism interacts with many species and those interactions are complex.

A Scientific Name for Deathcamas: Deathcamas was named Zigadenus in the late 1700s, for zygos, Greek for yoke and aden a gland, referring to a pair of glands on the flower. Despite the word's origin, the namer, Michaux, spelled it with an i, not a y. Other people, recognizing that zig- was really zyg-, corrected it, and you can see that in the literature. However, the rules of biological nomenclature are that if the name is properly published, then that's the correct spelling, even if it includes a mistake. An act of the International Congress of Plant Taxonomists could change the spelling of Zigadenus, but unless they do, the correct spelling is Zigadenus

The other names you see, Toxicoscordion in Colorado, others elsewhere (wikipedia page), for plants formerly called Zigadenus, result from experts determining that the plant species that were named Zigadenus were not all closely related and should be separated into several groups (genera). The first plant named historically almost always gets to keep the genus name, and in this case that is a plant of the southeastern United States (Zigadenus glaberrimus of the pine forests of the South), which happened to be distinctive and not like any other species. Consequently, all the others got new names. 

Name revision in botany requires first that someone do a study and publish changes, describing their logic. Then it requires that other botanists consider the paper and agree. If so, they will use the changed names. If they disagree, however, they will go on using older names. There seems to be no consensus in the case of deathcamases. I looked in all my favorite places, especially the Flora of North America, USDA Plants database, GRIN (U.S. National Germplasm System), the Plant List, and the Angiosperm Phylogeny webpage (which links to Kew Gardens in England, see Melanthiaceae). Two of them use Toxicoscordion and the other three Zigadenus. All are websites that are up-to-date except the Flora of North America, where the Liliaceae was published more than a decade ago (one of the three using Zigadenus).

When, like me, you don't know enough to judge whether splitting Zigadenus was a good idea or not, you find an authority and use the names it chose. So I'm using The Angiosperm Phylogeny website as my authority. They say Zigadenus, so I will. 


meadow deathcamas, Zigadenus venenosus

Eventually this will sort out, usually because more evidence comes in, showing the plants are indeed very different, so the split will hold, or that they are not so different, in which case all or most of the species will stay in/go back into Zigadenus

This is a time of wonderful progress in the plant sciences--all kinds of new discoveries!--but that new information is reorganizing things, rearranging plant families and changing plant names. We just have to flow with it.

Fortunately deathcamas has only one common name so you can look it up by common name. It does get spelled two ways, death camas and deathcamas. I like the second because it makes it clearer that deathcamas is not related to blue camas (also called common camas). Blogspot prefers death camas and keeps adding the space.

Beautiful, Deadly, Deathcamas: I have been warned against the dangers of deathcamas for years. But its a lovely plant, striking to see in flower. If you spot it in flower this spring, stop and look to see if there are any insects on the flowers. Adrenid bees and syrphid flies are neat insects! And, if you live where mule deer roam, see if the tips have been bitten off of the leaves. Just don't taste it yourself!

Comments and corrections welcome.

References
Brasher, J.W. 2009. A new combination in Toixicoscordion (Melanthiaceae) for the Rocky Mountain Region. Novon. 19 (3): 295-6.
Burrows, G.E. and R. J. Tyrl. 2013. Liliaceae.  In: Toxic Plants of North America. 2nd ed. John Wiley Company and Sons, New York.
Elpel, T. J. and K. Reed. 2014 Foraging the Mountain West. HOPS Press, Pony MT. 
Harrington, H. D. 1967. Edible Native Plants of the Rocky Mountains. University of New Mexico Press, Tempe.
Irwin, R. E., D. Cook, C.L. Richardson, J.S. Manson and D. R. Gardner. 2014 Secondary compounds in floral rewards of toxic range wants: Impact on pollination. Journal of Agricultural and Food Chemistry. 62 (30): 7335-7344.
Longland, W.S. and C. Clements. 1995. Consumption of a toic plant (Zigadenus paniculatus) by mule deer. Great Basin Naturalist. 55 (2): 188-191.
Peterson, M.C. and G. J. Rasmussen. 2003. Intoxication with foothill camas (Zigadenus paniculatus). Journal of Toxicology Clinical Toxicology 41(1): 63-65.
Tepedino, V.J. 1982. Effects of defoliation on reproduction of a toxic range plant, Zigadenus paniculatus. Great Basin Naturalist. 42 (4): 524-527.
Tepedino, V.J. 1981. Notes on the reproductive biology of Zigadenus paniculatus, a toxic range plant. Great Basin Naturalist. 41 (4): 427-430.
Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora Western Slope. 4th ed. University of Colorado Press, Boulder CO.
Zomlefer, W. B. and W. S. Judd. 2002. Resurrection of segregates of the polyphyletic genus Zigadenus s. l. (Lilies: Melanthiaceae) and resulting new combinations. Novon. 12: 299-308.

In J. Ackerfield, Flora of Colorado, 2015, Zigadenus venenosus is a treated as a synonym of  (that is, just another name for) Z. paniculatus. That is not the case for other sources I consulted. It is likely that the studies of Z. paniculatus apply to other grassland deathcamases, but they may not.

Related Posts: Devil's Backbone Hike  and Poisonous Plants

Kathy Keeler
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