SILPHIUM

FAMILY: Asteraceae

TYPE
  • Perennials
SUN EXPOSURE
  • Full Sun
  • Partial Shade
WATER
  • Moderate Water
  • Regular Water
PLANTING ZONES
  • US (Upper South) / Zone 6
  • MS (Middle South) / Zone 7
  • LS (Lower South) / Zone 8
  • CS (Coastal South) / Zone 9

Plant Details

Native to the Midwestern prairies as well as the scrublands of the Southeast, these tough, pest-free, underappreciated perennials feature tall spikes of showy, sunflower-like blooms in mid- to late summer. Broken stems exude a gummy sap that smells like pine or turpentinehence the common name rosinweed. Erect stalks holding loose, branching clusters of blooms rise from a clump of large basal leaves; stalk leaves are smaller. In most species, the foliage is rough and hairy. Plants tolerate wet or dry conditions, grow particularly well in heavy soil. Easily started from seed or grown from young transplants. Good additions to wildflower meadows, naturalized areas, and (if staked) the back of the border. Resist deer.

starry rosinweed

silphium dentatum

  • To 6 feet tall, 23 feet wide.
  • Dark green, shallowly toothed leaves reach 1 feet long.
  • Star-shaped light yellow flowers with greenish yellow centers reach 4 inches across.

compass plant

silphium laciniatum

  • Common name refers to the basal leaves' tendency to orient themselves on a north-south axis.
  • Foliage is green with pink veins; deeply cut basal leaves reach 112 feet long, form a clump 2 feet across.
  • Blossom stalks rise 69 feet high, carrying showy yellow flowers up to 5 inches across.

cup plant

silphium perfoliatum

  • Paired basal leaves are fused at the squarish stems, forming a cup that catches water; birds and butterflies will stop by for a sip.
  • Dark green, nearly hairless, coarsely toothed leaves reach 14 inches long, may be triangular or pointed-oval; plant grows about 3 feet wide.
  • Stalks rising 48 feet bear bright yellow, daisylike flowers up to 3 inches wide.
  • Grows naturally in moist soils; provide regular water.

prairie dock

silphium terebinthinaceum

  • Light green, spade-shaped basal leaves with coarsely toothed edges can reach 2 feet long.
  • Almost leafless flower stalks range from 310 feet tall, may be red or green; blossoms are bright yellow, 23 inches wide.
  • Plants reach 46 feet wide.
  • Once the stout taproot is established, prairie dock tolerates considerable drought.

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