Eryngium yuccifolium

This interesting prairie inhabitant sports umbels of orbicular, button-like flower heads that range in color from white to bluish-white.  It's pollinators include long-tongued and short-tongued bees, wasps, flies, butterflies, skippers, moths, and beetles.  It has a honey scented nectar.  Native Americans used the flower heads as ceremonial rattles.

Eryngium yuccifolium, commonly called Rattlesnake-master or button snake-root, is a native plant which occurs in rocky woods, prairies and glades throughout the State and was a common plant of the tallgrass prairie. Most members of the parsley/carrot family (Apiaceae) have finely cut foliage and flowers in domed umbels. Not so with rattlesnake-master which features basal rosettes of parallel-veined, bristly-edged, sword-shaped, medium green leaves (to 3' long) resembling those of yucca (lily family) and tiny, stemless, greenish-white flowers tightly packed into globular, 1" diameter heads resembling thistles (composite family). Flower heads appear in branched clusters at the top of smooth stiff stems typically rising to 3-4' (less frequently to 5-6') tall from the centers of the rosettes. Flower heads are subtended by whitish, pointed bracts.  It is easily grown in average, dry to medium, well-drained soils in full sun, but prefers dryish, sandy soils. Self-seeds in optimum growing conditions. Plants tend to open up and sprawl if grown in overly fertile soils or in anything less than full sun. This is a taprooted plant which transplants poorly and is best left undisturbed once established.

The genus name comes from an ancient Greek name used by Theophrastus for a plant which grew in Greece (probably Eryngium campestre) or is a Greek reference to the prickly or spiny nature of plants in this genus.

The common name is in reference to a former use of this plant as a treatment for rattlesnake bite.

There are no serious insect or disease problems. Taller plants may need support, however staking of these substantial plants in a cosmetically acceptable manner can be difficult. Massing plants in naturalized areas where they can provide some support to each other may be the best solution for this problem

Information adapted from: Missouri Botanical Garden