Toxicoscordion venenosum: Difference between revisions

Toxicoscordion venenosum
Toxicoscordion venenosum flowering Black Hills, South Dakota
Conservation status
Secure  (NatureServe)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Monocots
Order:	Liliales
Family:	Melanthiaceae
Genus:	Toxicoscordion
Species:	T. venenosum
Binomial name
Toxicoscordion venenosum (S.Watson) Rydb.
Varieties[2]
Toxicoscordion venenosum var. gramineum (Rydb.) Brasher Toxicoscordion venenosum var. venenosum
Synonyms[2][3][4]
List Toxicoscordion acutum (Rydb.) Rydb. Toxicoscordion arenicola A.Heller Toxicoscordion falcatum (Rydb.) Rydb. Toxicoscordion gramineum (Rydb.) Rydb. Toxicoscordion intermedium (Rydb.) Rydb. Toxicoscordion salinum (A.Nelson) R.R.Gates Zigadenus acutus Rydb. Zigadenus falcatus Rydb. Zigadenus gramineus Rydb. Zigadenus intermedius Rydb. Zigadenus diegoensis Davidson Zigadenus salinus A.Nelson Zigadenus venenosus S.Watson

Toxicoscordion venenosum, with the common names death camas and meadow death camas, is a species of flowering plant in the family Melanthiaceae. It is named for its well known toxic qualities with its common names and scientific name referencing this. Because its nectar is also poisonous, it is mainly pollinated by the death camas miner bee, which specializes collecting the toxic pollen for its young. It is native to western North America from New Mexico to Saskatchewan and west to the Pacific Ocean.

Description

Toxicoscordion venenosum is a bulb plant 20–70 centimeters tall when flowering in the spring or early summer. The underground bulbs are egg-shaped (ovoid) and made of up of multiple layers protected by dried outer layers (tunicate) like an onion.^[5]

The plant's leaves appears very early in the spring and are narrow.^[6] Most of the leaves spring directly from the ground (basal leaves), though a few much smaller ones may attach to the flowering stem.^[7] The length of the leaf blade is 12–50 centimeters long while only being 2–10 millimeters wide.^[5] The leaves are sharply folded into a "V" shape along their length, quite unlike the leaves of wild onions,^[8] with a ridge at the bottom of the fold (keel).^[9]

Flowering

The inflorescence usually does not have branches and is a raceme, but will sometimes have one or two branches near the base and be a panicle.^[7] If a plant does have branches they will one tenth to one third the length of the stem. It may be as much as 20 centimeters long, or as short as 2 centimeters. There may be ten to fifty flowers on the flowering stem. The top of the flowering stem will be pyramidal in shape when blooming begins with smaller buds and immature flowers towards the top and open flowers towards the base.^[5]

The flowers are off-white and resemble six pointed stars.^[10] The petals and sepals are very similar to each other and so are often called tepals.^[7] Together they are called a perianth and are 5–10 millimeters in diameter.^[5] The outer three tepals are egg shaped (ovate) and strongly curved inward while the inner three are shaped more like a spear head (lanceolate) and are more yellow or yellowish-green than the outer three. Each flower has six stamens each as long or slightly longer than the tepals.^[7] The bracts on the back of the flowers may be green or white and are 5–25 millimeters long.^[5] Flowering may comence in April, May, June, or as late as July in its native habitat.^[11][12]

The fruit is a capsule 8–20 millimeters long and 4–7 millimeters wide.^[5] The tepals persist into fruiting.^[7] The seeds are 5–6 millimeters long and light brown in color.^[9]

The closely related foothills death camas (Toxicoscordion paniculatum) has a very similar appearance, but with smaller flowers, more open clusters, and multiple flowers on each stemlet (a panicle).^[13]

A diploid, its chromosome count is 2n = 22.^[14]

Taxonomy

Toxicoscordion venenosum was given its first scientific name, Zigadenus venenosus, and described by Sereno Watson in 1879.^[2][15] The botanist Per Axel Rydberg proposed the new genus Toxicoscordion in 1903 and placed the species there.^[2] Most sources in the 20th century continued to classify it in Zigadenus, however genetic research published in 2002 resurrected the genus Toxicoscordion.^[16]

As of 2024^[update] this is the accepted name according to Plants of the World Online and World Flora Online.^[2][17] However, many sources such as the Flora of North America still list it as Zigadenus venenosus.^[5]

Varieties

Two varieties of this species are accepted.^[2]

Toxicoscordion venenosum var. gramineum

This variety was first described by Per Axel Rydberg as a species named Zigadenus gramineus in 1900.^[3] However, it was generally recognized as a separate species until the 21st century.^[18] This variety is differentiated by more often having branches on it flowering stems and the outer tepals being less curved (clawed) than in var. venenosum. It is found in the Pacific Northwest, Colorado, Canada, and the northern plains, much more widely spread than the other variety.^[11]

Toxicoscordion venenosum var. venenosum

The autonymic variety almost never has branches on its flowering stem, at most having just one branch. The outer tepals of the flowers are clawed and 5 millimeters long.^[12] It it found on the west coast of North America from British Columbia to Baja California in Mexico.^[19][4] It is not found further east than Nevada, Idaho, or Utah.^[12]

Names

The genus name Toxicoscordion is derived from Greek and means "poison garlic". The species portion of its binomial name, venenosum, appropriately translates as "very poisonous".^[8] In English it is often simply called "death camas",^[20] a name also applied to other species in the genus.^[21] More specifically it is known as "meadow death-camas" to distinguish it from other related plants.^[22] The variety gramineum is sometimes called "grassy deathcamas".^[23] The "camas" part of its name is due the resemblance of the bulbs to those of the edible Camassia flowers.^[24] Other common names include "poison onion" and "poison camas".^[25]

In the Northern Pomo language all members of the genus including this species are called "tsim’bu" meaning "harmful bulb".^[26] Likewise in the Umatilla language from along the Columbia River this species is called "alapíšaš", but the related Toxicoscordion paniculatum and even Anticlea elegans may have also been called by this name.^[27] In the Ktunaxa language of British Columbia it is called "nupqasaquǂ" ("nup-ka-sa-qush").^[28] In the Lushootseed language of South Puget Sound it is called "ba'q'a'".^[29]

Toxicity

Toxicoscordion venenosum has a well deserved poisonous reputation.^[20] The main toxic alkaloid contained in the plants is zygacine, but other esters of zygadenine develop in the plant as the seed pods ripen.^[30] While they are not easily confused with other species while in bloom they can easily be mistaken for edible bulbs like those of the camas lily in the Pacific Northwest once the leaves and flowering stems have faded.^[20] As few as two bulbs are sufficient to kill a fully-grown human, with the poisons not degraded by cooking.^[25] The toxins also remain stable when dried and stored, with bulbs remaining toxic for two decades after collection.^[31] The seeds and the bulbs are the most toxic parts of the plants.^[7] A survivor of poisoning said of the experience, "My mouth got tingly, and later the sensation moved down my throat."^[32]

Human poisonings are rare. Symptoms of poisoning are numerous. The first symptom is watering of the mouth followed by numbness of the lips and mouth. Other possible gastric symptoms include thirst, nausea, stomach pain, vomiting, and diarrhea. Circulatory, nervous, and muscular symptoms may include a headache, muscular weakness, confusion, slow and/or irregular heartbeat, low blood pressure, below normal temperature, difficulty breathing, convulsions, or coma. In severe cases coma is followed by death. The onset of symptoms ranges from one to eight hours after consumption. A number of edible bulb species have been mistaken for meadow death camas including blue camas, wild onions, and mariposa lily.^[33]

The plant is also deadly to livestock, with sheep being most commonly poisoned.^[30] However, pigs are reported to vomit the plant and avoid being fatally poisoned.^[34] The lethal dose of green plant material is between 0.6% and 6.0% of an animal's body weight.^[35] In experiments with sheep it was among the most poisonous of members of its genus with just 0.4% of green material by body weight causing symptoms, close to the 0.2% of Toxicoscordion nuttallii. And material from T. venenosum var. gramineum was almost as equally fatal at just 0.6% compaired with 0.5% for T. nuttallii.^[36] As a plant develops towards flowering the levels of zygacine decrease in the plant. The plants tend to have higher levels of poison in dry locations and in years with less rainfall.^[30]

Range and habitat

Meadow deathcamas is found through much of western North America. In Canada it is found in three western provinces Alberta, British Columbia, and Saskatchewan. In the United States it grows from the West Coast to Rocky Mountains with the exception of the state of Arizona. This includes California, Colorado, Idaho, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming.^[2] It also grows in the Mexican state of Baja California.^[19]

The meadow deathcamas grows in more open, sunny habitats. The variety venenosum grows in grasslands and open pine woodlands of the interior from 500 to 1300 meters.^[12] The variety gramineum grows in well drained grasslands and coastal areas from sea level to as much as 2500 meters.^[11] They prefer wet areas, but can grow in much drier habitats than common camas (Camassia quamash) such as on hillsides in the Sierra Nevada Mountains.^[8] They may also be found in opening in coniferous forests and among the sagebrush of the interior.^[9]

Ecology

The nectar is also poisonous and controlled experiments have shown that honeybees can be fatally poisoned by the flowers and it or its relative are suspected in a few cases of honeybee poisonings.^[37][32] The plant is visited by a specialist mining bee, the death camas mining bee (Andrena astragali), which is likely the only bee that can tolerate its toxins.^[38] In turn the bee is an oligolege, a species that specializes in the pollen of only a few species of flower. The death camas mining bee specializes in meadow deathcamas and the closely related Toxicoscordion paniculatum. Seed production for the plant is also significantly increased by bees visiting the flowers.^[39] Theories as what advantages specialization and toleration of the toxicity of the nectar and pollen provide include that the lack of competitors for the food resources provided by the flowers and that like the Monarch Butterfly ingesting toxic food protects the bees from predators and parasites by making them toxic.^[32]

Though the death camas bee is the only bee that feeds upon death camas flowers, a fly species, Earomyia melnickae, was described in 2022 which was discovered feeding on the meadow death camas flowers. As of 2024^[update] it is unknown where or what the species may feed upon as a larva. Extensive searches were made on the bulbs in the area where the flies were discovered, but no signs of feeding or larvae were discovered. It is also unknown if they contribute to pollination of the flowers to any degree.^[40]

As a bulb plant, it survives fires easily. Though plants that are actively growing will be consumed in a fire the bulb will survive and regenerate. When dormant the bulbs are apparently entirely unaffected by fires. They grow in a variety of habitats with different fire intervals, from as infrequent as more than 400 years between fires to as frequent as yearly fires in some ponderosa pine forests.^[31]

Conservation

When evaluated by NatureServe in 2015 it was found to be "Secure" at the global level (G5). They also found it to be secure in British Columbia, Montana, and Wyoming (S5) and "Apparently Secure" (S4) in the provinces of Alberta and Saskatchewan.^[1]

Cultivation

The naturalist Ira Noel Gabrielson dismissed it and all of its relatives except for Toxicoscordion fremontii as not having, "charm enough to take up room in a garden when so many more beautiful things are available."^[41] Despite this, very rarely, this species is grown in gardens. Though due to the toxic nature of it and all its relatives caution is urged to avoid planting it where herbivores would have access. In the Manual of Bulbs from the Royal Horticultural Society it is listed as tolerating winter temperatures at least as cold as −15 °C (5 °F).^[42]

References

External links

Wikimedia Commons has media related to Toxicoscordion venenosum.

• Calflora Database: Toxicoscordion venenosum (Meadow deathcamas)
• iNaturalist – Meadow Deathcamas Toxicoscordion venenosum
• Jepson Manual eFlora (TJM2) treatment of Toxicoscordion venenosum var. venenosum
• USDA Plants Profile for Zigadenus venenosus (meadow deathcamas)
• Lady Bird Johnson Wild Flower Center: Zigadenus venenosus (Meadow death camas, death camas)
• Turner Photographics, Wildflowers of the Pacific Northwest: Zigadenus venenosus (Meadow death camas)
• UC Photos gallery — Toxicoscordion venenosum