Larkspur Poisoning

Medically Reviewed by Dany Paul Baby, MD on November 04, 2022
6 min read

Fields of purple flowers can look romantic and inviting, but some can harbor a dark secret. Larkspur is a toxic wildflower that grows mostly in the western U.S. While human poisonings are rare, larkspur often causes severe illness and death in cattle. 

Larkspurs are a group of purple and blue wildflowers from the family Delphinium. There are many varieties of larkspur, and they’re divided into three groups: tall larkspurs, low larkspurs, and plains larkspurs.

Tall larkspur. Tall larkspurs get their name from their height, as the plants often grow three to six feet tall. They most often grow in deep, moist soil at elevations above 7000 feet. Tall larkspurs are often found in the Rocky Mountain region in mountain valleys and meadows and along streams and springs. They usually start to grow once the snow melts but don’t reach their full height until July.

Common variations of tall larkspur include:

  • Delphinium barbeyi. Commonly called the Subalpine Larkspur, Delphinium barbeyi usually grows up to about five feet. The dark purple flowers bloom in July and August. Delphinium barbeyi is found in Arizona, Colorado, New Mexico, Utah, and Wyoming and typically grows in the shade of subalpine streams and on the edges of meadows.
  • Delphinium glaucescens. Delphinium glaucescens is also called the Electric Peak Larkspur, Glaucous Larkspur, and Smooth Larkspur. The blue and white flowers blossom in the summer, from June-August. They grow up to three feet tall in the rocky slopes of subalpine coniferous woods, that is, woods that grow trees like pine and spruce. They can be found in Idaho and Montana.
  • Delphinium occidentale. The Duncecap Larkspur, Delphinium occidentale, grows blue, purple, and white flowers that bloom in July and August. They are one of the most widespread types of larkspur, native to Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, Utah, Washington, and Wyoming. 

Low larkspurs. Low larkspurs grow at lower elevations, although sometimes they can be found growing alongside tall larkspurs at higher elevations. They usually only grow to about two feet tall. They start to grow early in the spring, before most other types of foliage and are usually found on grassy hillsides and near sagebrush.

Species of low larkspur include:

  • Delphinium bicolour. Also called the Flat-head Larkspur and Little Larkspur, Delphinium bicolour can grow to a height of anywhere between 4-24 inches. The flowers bloom from May through July, with petals that transition from dark blue to pale blue and purple. These wildflowers are found in grasslands, pine forests, and rocky slopes in Idaho, Monana, North Dakota, South Dakota, and Wyoming.
  • Delphinium nuttallianum. Delphinium nuttallianum, sometimes also called Delphinium nelsonii, is more commonly referred to as the Two-lobe Larkspur or just Delphinium. Delphinium nuttallianum is often representative of several species of low larkspur, as the various species can be difficult to tell apart. The plants can range in size from 6-30 inches tall. Their flowers bloom between March and July and come in shades of blue, purple, and white. In the U.S. they can be found in Arizona, California, Colorado, Idaho, Montana, Nebraska, New Mexico, Nevada, Oregon, South Dakota, Utah, Washington, Wyoming, and within Canada in British Columbia.  

Plains Larkspurs. Like low larkspurs, plains larkspurs begin growing early in the spring, before most other types of foliage. They tend to have weak stems and grow to about the same heights as low larkspurs. True to their name, they’re mainly found in the plains of western states.

Species of plains larkspurs include:

  • Delphinium carolinianum. Common names of Delphinium carolinianum include Blue Larkspur, Carolina Larkspur, and Prairie Larkspur. They typically grow one to two feet tall. The flowers vary in color in shades of blue, purple, and white, and bloom from April to July. Delphinium carolinianum can be found further east than many other species of larkspur. They grow in brushlands, dry woods, and sandy hills in Alabama, Arkansas, Colorado, Florida, Georgia, Iowa, Illinois, Kansas, Kentucky, Louisiana, Minnesota, Missouri, Mississippi, North Dakota, Nebraska, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, and Wisconsin. 
  • Delphinium geyeri. Commonly called Geyer’s Larkspur or Poison weed, Delphinium geyeri can grow up to 30 inches tall. They grow blue and white flowers from May to June. Delphinium geyeri are found in the grasslands or scrublands of Colorado, Nebraska, Utah, and Wyoming.

What is larkspur used for? Larkspur doesn’t have many medicinal uses but is sometimes used in herbal treatments for lice and other parasites.

There are many, many species of larkspur. Characteristics that are generally shared between larkspur variations that can help with larkspur identification include:

  • Individual flowers are small and come in shades of blue, purple, and white, sometimes cream and pink.
  • Flowers grow in vertical bunches, called racemes, on very short floral stalks.
  • Larkspurs grow in upright stalks, not in bushes.
  • Stems are hollow.
  • Leaves alternate and are divided.

All parts of the larkspur plant are poisonous. When touched, the leaves and seeds can cause skin irritation. Eating the plant can cause severe illness and death.

Cattle are most likely to have larkspur poisoning. As larkspur are some of the first plants to blossom, there may not be many other grazing options for cattle. Larkspur plants contain a few different types of poisons. Larkspur toxicity is highest during the early stages of growth, but the plants remain toxic through their entire lifespan.  

Sheep and goats are not affected by larkspur, and can be used to graze away larkspur in fields and ranges.

Poisoning in humans due to eating the larkspur plant is rare. Instead, humans are more likely to have skin symptoms from touching the leaves or seeds of the larkspur plant. Symptoms may include:

  • Bumps
  • Blisters
  • Itching
  • Red patches or rash
  • Swelling

Symptoms of poisoning from eating larkspur include:

  • Agitation or nervousness
  • Bloating
  • Muscle twitching
  • Muscle weakness
  • Nausea and vomiting
  • Paralysis
  • Rapid and irregular pulse

Skin irritation caused by larkspur can usually be treated at home. Take these steps to reduce symptoms:

  • Thoroughly wash the area with dish soap, rubbing alcohol, or a poison plant wash. Use a lot of water and rinse frequently.
  • If you were handling larkspur, scrub under your nails with a brush.
  • Apply soothing balms like calamine lotion or hydrocortisone cream to reduce irritation.
  • Widespread itching can also be relieved with an oatmeal bath.
  • Take an antihistamine like Benadryl to reduce your reaction.
  • In cases of severe exposure or exposure to your face or genitals, get medical care.

If you discover you’ve ingested the larkspur, contact poison control. You can chat with someone online or speak to someone on their toll-free hotline at 1-800-222-1222. They will take information like your age, weight, the amount you ingested, and how long ago you ingested it, the larkspur poisoning symptoms you’re experiencing, and give you advice based on that. 

Poison control may recommend that you go to the hospital. There is no treatment for larkspur poisoning. Larkspur treatment involves managing the symptoms of poisoning until the poison clears your system.

There are a few safe wildflowers that have a similar look to larkspur. These include:

  • Lavandula angustifolia. Many species of lavender have flowers with a similar look to larkspur. Lavandula angustifolia, or English lavender, is the most widespread species. It grows in purple bunches similar to larkspur but on a more bush-like plant.
  • Lythrum salicaria. Also called Purple Loosestrife, the flowers grow in bunches similar to those of larkspur, but the flowers are more of a magenta color and grow in wetlands. 
  • Vicia villosa. Often known as Winter Vetch or Hairy Vetch, the flowers come in shades of purple and all grow on the same side of the stalk. Note that the seeds can cause health problems in animals, most often horses and cattle.