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Eryngium aquaticum

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Plant types and subtypes: Biennials

Light Requirements: sun, part-sun

Water Use: medium

Soil Moisture: moist, wet

Soil Description: acid, neutral, average, loam, sand

Height: 3'-5'

Bloom Time: July, August, September

Bloom Color: white, blue

Leaf Color: blue-green, gray-green

Hardiness Zone: 6, 7, 8, 9

Additional Tags: attracts bees, attracts birds, attracts butterflies, bog plant, clumping, colonizing, cut flowers, deer resistant, dried flowers, medicinal, naturalizing, ornamental foliage, pond margin plant, salt tolerant, stream margin plant, swamp plant, water garden plant, wetland plant

Eryngium aquaticum (rattlesnakemaster)
  • Eryngium aquaticum (rattlesnakemaster)
  • Eryngium aquaticum (rattlesnakemaster)
  • Eryngium aquaticum (rattlesnakemaster)
  • Eryngium aquaticum (rattlesnakemaster)

Pricing & Availability


Eryngium aquaticum

Also known as:



rattlesnake master


corn snakeroot


bitter snakeroot


marsh eryngo


sea holly

Scientific Synonyms:


Eryngium aquaticum is a striking perennial with silvery foliage and blueish flowers. The leaves predominantly basal, alternate, lance-shaped with spiny margins, and up to to 2' long by 2 1/2" across. Each plant produces a single, ribbed central stem that is terminally divided into flower-bearing branchelets. The flowers are globe-shaped, whitish with shades of blue, and cupped by conspicuous, spiny silvery bracts.


This species of rattlesnake master occurs naturally in wetlands and bogs, where it can be exposed to periods of inundation, but it adapts well to cultivation in more typical garden settings so long as the soil is not allowed to dry out for extended periods of time. This is a sun-loving species, that will tend to grow lanky and weak with too much shade. Rich, light soil is best. Heavy soils should be amended with ample organic matter. The blooming period lasts about 1 1/2 months, from mid-summer through early fall, with the dried flowerheads providing visual interest well into winter. Zones 6-9


This species does not like to be disturbed, but can be propagated by carefully dividing plants in early spring, or by making root cuttings when dormant. Seeds are very attractive to birds, and there is only a narrow window to collect them between the time they are ripe (the seedheads turn light-brown), and before they have been eaten.

Additional Notes

Rarely seen in cultivation, or sold commercially, this stunningly beautiful species is worthy of more attention, and is an excellent choice for use in rain gardens. It is very attractive to pollinators and highly deer resistant.

Native Range & Classification

Recorded County Distribution: USDA data

Native Range:

USDA Endangered Status:

  • Extirpated: PA


Kingdom Plantae Plants
Subkingdom Tracheobionta Vascular plants
Superdivision Spermatophyta Seed plants
Division Magnoliophyta Flowering plants
Class Magnoliopsida Dicotyledons
Subclass Rosidae
Order Apiales
Family Apiaceae Carrot family
Genus Eryngium eryngo
Species Eryngium aquaticum rattlesnakemaster