I shot this image of blue sea holly, a type of eryngium, at Cheekwood Botanical Gardens in Nashville on a too sunny, too muggy, too hot southern summer day.
Blue sea holly is a silver-blue annual perennial herb known by many names: eryngium, eryngo, sea holly, blue sea holly, and big blue. Though it borrows the name, it is not a holly.
Well-known British garden enthusiast Ellen Wilmott loved sea holly so much she always kept some seeds in her pocket. If she came upon a garden she considered to be boring, she scattered a few sea holly seeds and moved on. When the seeds sprouted in all the places Miss Wilmott visited, the plant became affectionately known as Miss Wilmott's Ghost.
I would call blue sea holly a thistle. It has spiny leaves and a spiny, bulbous, dome-shaped umbel that makes it deer proof. Deer might get a mouthful of blue sea holly once but never again.
Although native to Europe, the Mediterranean, the Caucasus, and Iran, in the Americas, eryngium is most prolific and diverse in South America. It is a hearty plant that tolerates drought, wind, salt sprays, and sandy soil. It is most at home in grassland areas but can be seen in rocky and coastal areas as well. And it is a very popular addition to flowerbeds, floral arrangements, and wedding bouquets.
Blue sea holly thrives in full sun and moist, sandy soil with good drainage but its long taproot that goes deep in the earth to seek moisture allows it to survive poor soil conditions and drought. Because of its long taproot, blue sea holly doesn’t transplant well but is easily grown from seed.
It is a great plant for difficult environments and, when planted on the perimeter of a garden, will help deter deer. It will also attract butterflies.
Variations of eryngium are used as folk medicine in Turkey, to relieve scorpion stings in Jordan, and as an anti-inflammatory treatment in many parts of the world.
The roots can be used as vegetables; young shoots and leaves can be used as an asparagus-like vegetable; and it is used as a spice and sometimes called spiny cilantro or coriander because it is easily mistaken for those spices.
Look but don’t touch. Like deer, you may have a bad encounter with blue sea holly’s spiny leaves and spiny umbel once…but never again.