Contrary to its name, this 4-5' tall evergreen perennial attracts a huge diversity of insects, not rattlesnakes!  It also adds a unique texture and silvery, blue-green color to the landscape and to cut-flower arrangements.  Preferring full sun and dry to average, well-drained soils, this adaptable plant features bristly, thistle-like flower heads densely packed with tiny, greenish-white florets from May through August.  The spherical heads sit atop rigid stems with spiky, blue-green foliage that resembles that of the yucca plant.  Besides being difficult to walk through, the spiny leaves are unpalatable to most animals.  Although it looks like a thistle, rattlesnake master is a member of the carrot family and is a true tallgrass prairie species.  It has many of the same oils and aromas as parsley, carrot, and parsnip. 
 
The common name “rattlesnake master,” (it’s also called button snakeroot and yucca-leaf eryngo), comes from Native Americans’ use of the sap as a preventative to snakebite during the ceremonial handling of rattlesnakes.  The plant grows in clumps and is an aggressive self-seeder if the spent flower heads are not removed.  The strong tap root stores water and helps it tolerate drought; moist, fertile soils and shadier conditions will cause it to sprawl.    
 
Native habitats include prairies, thickets, savannas, sandy roadsides, and open woods.  Plant it as a specimen or in groups in beds, borders, and naturalized areas where the white flower heads and bluish foliage will complement the vibrant colors of summer flowers. 
 
Plant Characteristics: 
Prefers full sun. 
 
Grows 3-5’ tall and 2-3’ wide. 
 
Grows in dry to medium clay, loam, and sand.   
 
Tiny, individual, greenish-white flowers consist of 5 white petals, a white pistil, and several white stamens.  The flowers are clustered into 1”, egg-shaped flower heads.   
 
Stout central stems are unbranched, except near the flower heads.  Narrow, stiff, lance-shaped leaves appear mostly at the base and scattered along the stem, growing shorter as they ascend until they are reduced to bracts around the flower heads. 
 
Wildlife Value: 
Host plant to 5 species of Lepidoptera larvae, including the black swallowtail shown here, celery leaftier, and Hawaiian beet webworm.  Wasps are primary pollinators, while long- and short-tongued bees, flies, beetles, and monarchs, skippers, and other butterflies visit the flower heads for nectar. Soldier beetles eat the pollen, and some bees collect pollen for their broods. 
 
The coarse foliage and prickly flower heads are not popular with mammals. 
 
Medicinal, Edible, and Other Uses: 
Though there is no evidence of its efficacy, Native Americans brewed a tea from the root as an antidote to rattlesnake venom. Concoctions from the leaves were used as an emetic.
 
Native Americans used the leaves to weave sandals and baskets and made rattles out of the dried seed heads.