Eryngium yuccifolium

Rattlesnake master provides a double feature with showy, globular flowers and striking foliage.

Mark Dwyer
Rattlesnake master is making increasing waves in residential landscapes as a durable workhorse of structural beauty, hardiness and longevity in the garden.

Are you looking for a hardy perennial that will not only perform well in the full sun garden but will also be a conversation piece for all that view it? Look no further than the beautiful and versatile rattlesnake master (Eryngium yuccifolium). This member of the parsley and carrot family (Apiaceae) has long been known by native plant enthusiasts for its striking foliage and long lasting, globular flower structures. However, rattlesnake master is making increasing waves in residential landscapes as a durable workhorse of structural beauty, hardiness and longevity in the garden.

Northern rattlesnake master, also called button snake-root and button eryngo, is hardy from USDA Zones 3-8 and requires full sun. There is a southern species with similar characteristics although the focus of this article is on the northern form. Tolerating drought, clay and shallow/rocky soils, this species prefers dry, sandy soils and relies on sharp drainage as it will not tolerate poor drainage or standing water. As a common plant in the tallgrass prairie, Eryngium yuccifolium has a wide native range throughout much of the eastern United States, southern Ontario to Florida and west to Iowa, Kansas and East Texas. This plant benefits from competition and surrounding plants which help support the flower stalks. In anything less than a full sun location or in overly fertile soils, this plant will become floppy and sprawling. Staking is quite challenging with this plant so do consider “supportive neighbors.” In addition, this plant is not adversely affected by walnut toxicity and has very few insect or disease problems.

Flower and foliage form

The foliage of Eryngium yuccifolium is quite interesting and features blue/green, basal rosettes of bristly-edged, sword-shaped leaves that resemble yucca (Yucca filamentosa). These foliar characteristics are referenced in the specific epithet, yuccifolium which means “like yucca”. The fibrous leaves are parallel-veined, long, narrow and can reach lengths of 30 inches. The flowering stems will feature a few leaves as well, but the bulk of the ornamental foliage is at the base of the plant. Grazing stock, deer and rabbits will leave this entire plant alone. The variety ‘Kershaw Blue’, introduced by Plant Delights Nursery, has an intensely blue cast to the foliage and is a stable seed strain. The common names for this plant reference Native American use to treat snakebites which was first described in the 1700s. There is some debate over this historical cultural use. The fibrous leaves were also used for weaving purposes by Native Americans to create a wide range of products including sandals and baskets.

The greenish-white, globular flowers are arranged on branched clusters at the top of smooth, stiff stems. The flowers are lightly fragrant and attract a wide range of pollinators including many species of wasps and native bees. The flower nectar is of interest to butterflies including monarchs. While the timing of the flowering for this perennial is “latitude dependent,” the process typically starts in late June with flower interest extending all the way through the summer. While the individual flower heads resemble thistles, they are not related. These flower heads are made up of an aggregation of many small, greenish-white florets mingling with pointed bracts. The coloration of the blooms transitions from green to white later in summer. When dormant, this plant stays quite rigid in winter and still offers tan coloration and a stiff form. Rattlesnake master can have a variable height dependent on soils and available moisture, but most often averages between 4-5 feet in bloom with the rosette of foliage much lower to the ground. The variety ‘Prairie Moon’ from Intrinsic Perennial Garden is a beautiful, compact selection that is consistently at 3 feet in maximum height.

In the landscape

Rattlesnake master has a long history of use in prairie restorations, meadow plantings, rain gardens and naturalistic combinations. As a taller, summer blooming perennial with very striking form and flowers, it is finding its way into water-wise landscape mixes and deer resistant plantings. This is an excellent component as an accent in a wildlife garden with its valuable nectar. The spiky, blue-toned leaves are also an ornamental feature and provide both contrast of form and texture with surrounding plantings. As a tap-rooted plant, rattlesnake master transplants poorly and is best left undisturbed after being installed in a permanent location. Division is also tricky although not impossible.

Scattered groupings or drifts are impactful in combinations where surrounding neighbors like ornamental grasses can help create a supporting matrix (both literally and figuratively). Rattlesnake master mingles well with native grasses such as big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), switch grass (Panicum virgatum), Indian grass (Sorghastrum nutans) and prairie dropseed (Sporobolus heterolepis). Some great companion perennials include the many species of Liatris, coneflowers (Echinacea sp.), butterfly weed (Asclepias tuberosa), ironweed (Vernonia sp.) and many more. It’s also noteworthy that rattlesnake master has found its way in to both fresh and dried arrangements.

In the trade

Availability of this plant as both seed and starter plants is usually quite strong in the spring. Native plant nurseries likely will be a good source. It is important to note that in optimum growing conditions, rattlesnake master will reseed robustly. Established, surrounding plant “neighbors” and minimal gaps will help curtail overly aggressive seeding which is more likely in “open soils”. Collected seed germinates best if stratified for a month or directly sown in the fall for spring germination. The varieties ‘Kershaw Blue’ and ‘Prairie Moon’ mentioned above are not easy to source at this point in time but are certainly worth the quest if you’re interested in a more intensely blue foliage or compact height respectively.

Rattlesnake master is a solid-performing, native perennial that has a proven track record of success as a beautiful plant in a wide range of appropriate situations. Consider adding this amazing plant to your full-sun arsenal.

Mark Dwyer was the Director of Horticulture at Rotary Botanical Gardens in Janesville, Wisconsin, for 21 years. He has degrees in landscape architecture and urban forestry and now operates a private consulting practice, Landscape Prescriptions by MD.

November 2021
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