Eryngium yuccifolium (Rattlesnake master)

Rattlesnake master, or button eryngo, is native to the lower half of Virginia. Wild populations of this plant are common in central states, but becoming scarse in Virginia, as human disturbance is reducing viable habitat.

Not a thistle or a yucca in spite of its appearance, rattlesnake master is a relative of the carrot (Apiaciae) family, with a deep taproot that breaks down through clay, sandy and rocky soils. It has attractive and thick blue-green foliage. The common name refers to this plant being used medicinally to treat snakebites in the past. 

180 documented varieties of butterflies, moths, wasps, beetles, flies and bees visit the unique pom-like flowerheads, abundant with nectar in summer. Eryngium yuccifolium is an uncommon host plant for black swallowtail butterflies.

 

It sports a non-aggressive clumping habit, but can spread by seed if happy in its location. This species prefers lean soils and heavy root competition in a plant community. Some associated companion species include little bluestem, splitbeard bluestem, purple lovegrass, Liatris squarrosa, field or pasture thistle (Cirsium discolor or pumilum), Appalachian sunflower (Helianthus atrorubens), ricebutton aster (Symphyotrichum dumosum), pussytoes (Antennaria), and Rudbeckia hirta.

The dry seed heads are sharp and prickly in winter. Its deep roots don’t like being disturbed so it’s best not to relocate after its established, but very young plants can be carefully relocated.