Common Name: false gromwell
Type: Herbaceous perennial
Family: Boraginaceae
Native Range: Eastern and southern United States
Zone: 3 to 8
Height: 2.00 to 3.00 feet
Spread: 2.00 to 3.00 feet
Bloom Time: June to July
Bloom Description: Creamy white to yellowish green
Sun: Full sun to part shade
Water: Dry to medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy
Fruit: Showy
Tolerate: Drought, Shallow-Rocky Soil
Culture
Easily grown in average, dry to medium, well-drained soils in full sun to part shade. Preference is for rocky or sandy soils. Tolerant of drought once established.
Noteworthy Characteristics
Onosmodium molle is commonly called false gromwell because of a perceived similarity in appearance to some of the gromwells (Lithospermum). This species is a coarse, hairy, somewhat weedy, woody-based perennial that is native from New York to Louisiana and New Mexico north to Saskachewan. It is typically found growing in rocky prairies, glades, thickets and open rocky woods/fields. It grows in an upright shrubby clump to 2-3’ tall, and is noted for its terminal, drooping, bracteose flowering spikes and white nutlets that follow the flowers. Tubular flowers appear in late spring to early summer, featuring 5 creamy white to yellowish-green petals and a distinctive style that extends beyond the end of the flowering tube. Hard white nutlets follow the flowers. Nutlets usually persist on the dead foliage throughout the winter. Nutlets give rise to the additional common name of marbleseed for plants in this genus. Sessile, ovate to lance-shaped leaves. Steyermark lists three subspecies of this plant as being indigenous to Missouri: O. molle subsp. occidentale, O. molle subsp. subsetosum and O. molle subsp. hispidissimum.
Genus name means resembling the genus Onosma.
Problems
No serious insect or disease problems.
Uses
This plant is of questionable use to the ornamental landscape. It is generally not carried by nurseries and may need to be purchased through native plant organizations or grown from seed collected from the wild. Interesting addition to prairies, open woodland areas or native plant gardens.