western marbleseed

Native

Moderately dry. Prairies, open woods. Full sun.

June to July

Dull white or greenish white

12″ to 28″

This is a 12″ to 28″ tall, erect or ascending, perennial forb that rises on several stems from a stout, woody root.

The stems are erect, leafy, and often unbranched below the inflorescence. They are moderately to densely covered with appressed-ascending hairs of about equal length and with scattered, loosely ascending to spreading hairs.

Basal leaves are absent and lower leaves withered or absent by the time the plant is in flower. Stem leaves are alternate, stalkless, unlobed, and untoothed. The leaf blades are lance-shaped to narrowly egg-shaped, ¾″ to 3⅛″ long, and ½″ to ¾″ wide. They are angled or tapered at the base and angled or tapered to a sharp point at the tip. There is a midvein and 2 or 3 pairs of lateral veins that curve toward the leaf tip. The veins are strongly recessed on the upper surface, strongly raised on the lower surface. The upper and lower leaf surfaces are densely covered with appressed to loosely appressed hairs, all of about equal length.

The inflorescence is a crowded, one-sided, coiled, unbranched, spike-like cluster (raceme) at the ends of the stem and branches. The shape of the raceme resembles a scorpion’s tail.

The flowers are ⅓″ to ⅔″ long, 1½ to 2 times as long as wide, and tubular-shaped, converging to a point near the tip with straight sides along the tip. The 5 petals are dull white or greenish white and hairy. The style protrudes from the floral tube. These flowers mature reproductively well before the petals are developed.

The fruit is a white, smooth, shiny, marble-like, ⅛″ to 3 ⁄16″ (3.5 to 5 mm) in diameter nutlet. It does not have a collar around the attachment point. It remains on the plant throughout the winter.

Softhair marbleseed (Lithospermum parviflorum) is the eastern species. It is a taller plant, up to 48″ tall. The leaves are much larger, up to 5½″long and 1½″ wide. The nutlet is dull and less than ⅛″ in diameter, and has a small collar around the attachment point.

Taxonomy
The nomenclature for this species has been in flux for the last decade. It was originally listed as Onosmodium molle ssp. occidentale. In 1995 it was renamed Onosmodium bejariense var. occidentale (Turner, 1995). In 2009, based on a reassessment of DNA data, all of the species in the genus Onosmodium and four other genera were transferred to the genus Lithospermum. This subspecies, along with ssp. hispidissimum (softhair marbleseed), became synonyms of Lithospermum onosmodium. In December, 2011, the former subspecies of Onosmodium bejariense were raised to specific rank (Cohen and Davis, 2011). The new name of this species, complete with author, is Lithospermum occidentale (Mack.) Weakley, Witsell & D. Estes.

The following reputable and current (online) sources do not agree on the scientific name for this plant.

Plant

Inflorescence

Leaves

Infructescence