Tradescantia tharpii

Species Native to Missouri
Common Name: spider lily 
Type: Herbaceous perennial
Family: Commelinaceae
Native Range: Texas, Missouri, Kansas, Oklahoma
Zone: 4 to 9
Height: 0.50 to 1.00 feet
Spread: 0.50 to 1.00 feet
Bloom Time: May to July
Bloom Description: Rose to purple
Sun: Part shade to full shade
Water: Medium
Maintenance: Medium
Suggested Use: Naturalize
Flower: Showy

Culture

Grow in moist, acidic, sandy, well-drained loams in part shade to full shade. Plants generally prefer moist soils but will tolerate drier sites. Deadhead each flower cluster after all buds in the cluster have opened in order to extend the bloom period. After plants produce seed in summer, foliage may decline considerably (go into semi-dormancy) at which point plants may be cut back hard. Cutting back stems almost to the ground will promote both new foliage growth and an additional late summer to fall bloom. Divide clumps when they become overcrowded. Plants will naturalize over time.

Noteworthy Characteristics

Tradescantia tharpii, commonly called Tharp spiderwort or shortstem spiderwort, is a compact, clump-forming perennial that is native to Missouri, Kansas, Oklahoma and Texas. In Missouri it is typically found in rocky prairies, open woodlands, glades, slopes and along railroad tracks in unglaciated prairies areas in six counties in the southwestern corner of the state (Steyermark). This is a small plant that grows to only 8-12” tall. Strap-like green foliage (6-12” long by 1” wide) reminiscent of dayflower emerges in spring. Three-petaled flowers (1” across) accented by contrasting yellow stamens bloom in May. Flowers are borne in terminal clusters (umbel-like cymes) atop short stiff stems. Flower petal color is typically rose to purple, but may less frequently be light pink, lavender or blue. Multiple flower buds form in each cluster, but individual flowers open up only a few at a time, each for only one day, blooming in succession from late April through May.

Genus name honors John Tradescant (1570-1638) and his son John Tradescant (1608-1662), botanists and successive gardeners to Charles I of England.

Specific epithet honors Benjamin Carroll Tharp (1885-1964), botanist and professor at the University of Texas.

When the stems of spiderworts are cut, a viscous stem secretion is released which becomes thread-like and silky upon hardening (like a spider’s web), hence the common name.

Problems

No serious insect or disease problems. Young shoots are susceptible to damage from snails and caterpillars. Spiderwort foliage often sprawls in an unattractive manner by mid-summer.

Garden Uses

Spring flowers and attractive foliage for shady areas. Rock gardens, borders, shade/woodland gardens, naturalized areas or moist areas along streams or ponds.