S. drummondii grows up to 12 inches tall. It is often branched at the base, forming clumps. Leaves are opposite and densely arranged. Each leaf is 1/3–3/4 inch long and mostly oval, occasionally somewhat oblong. Flowers grow in the axils of the leaflike bracts. They have 5 sepals and 5 bluish-purple petals united to form a 2-lipped blossom 2/3–1 inch long. The lower lip is notched. Skullcaps can be distinguished from other mints by the crest on the upper surface of the blossom. Most of them have small, oval or rounded leaves, and all have bluish-purple flowers.
The species name of this plant is named for Thomas Drummond, (ca. 1790-1835), naturalist, born in Scotland, around 1790. In 1830 he made a trip to America to collect specimens from the western and southern United States. In March, 1833, he arrived at Velasco, Texas to begin his collecting work in that area. He spent twenty-one months working the area between Galveston Island and the Edwards Plateau, especially along the Brazos, Colorado, and Guadalupe rivers. His collections were the first made in Texas that were extensively distributed among the museums and scientific institutions of the world. He collected 750 species of plants and 150 specimens of birds. Drummond had hoped to make a complete botanical survey of Texas, but he died in Havana, Cuba, in 1835, while making a collecting tour of that island.