General: Herb to 30 cm high, with terete stems that are branched, brittle, pilosulous or glabrous, and generally weak–stemmed. Leaves: Blades lanceolate to ovate–lanceolate 1–7 cm long, .5–2.5 cm wide, obtuse at apex, rounded to cuneate at base, pilose; petioles to 8 mm long, slender, pilose. Flowers: Borne in terminal and lateral spikes to 9 cm long and about 8 mm in diameter, rachis glabrous or sparingly pilose; bracts lanceolate to ovate–lanceolate, 7–15 mm long, about 4 mm wide, acute, ending in spine 0.5 mm long, ciliate, 3–5–nerved, closely imbricate; corolla bilabiate 1 cm long, white to deep yellow with occasional purplish markings, glabrous, tube slender, lips 5 mm long, entire upper lip, lower 3–lobed, lobes elliptic, 3 mm long. Fruits: Capsule 4.5 mm long, pubescent or glabrate. Ecology: Found on dry open ground, slopes, and along arroyos and washes from 3,000–5,000 ft (914–1524 m); flowers September–June. Distribution: The most widely distributed species in the genus ranging from the southwestern United States, throughout Mexico and Central America to northern South America and the Galapagos. Notes: Its sprawling habit is distinctive and in flower it is delicate and beautiful. The purplish spot on the flared upper lip can be diagnostic if you are uncertain. Ethnobotany: Unknown Etymology: Tetramerium is from tetras– four and meris– part, meaning four parts, while nervosum means having distinct veins or nerves. Sources: Wiggins 1964, Daniel 1986, Daniel 1984, Kearney and Peebles 1969 

Wiggins 1964, Daniel 1986, Daniel 1984, Kearney and Peebles 1969

Duration: Perennial Nativity: Native Lifeform: Subshrub General: Perennial herb to 30 cm high, with terete stems that are branched, brittle, pilosulous or glabrous, and generally weak. Leaves: Leaves opposite and petiolate; petioles to 8 mm long, slender, pilose; blades lanceolate to ovate-lanceolate 1-7 cm long, up to 2.5 cm wide, obtuse at apex, rounded to cuneate at base, pilose. Flowers: Borne in terminal and lateral spikes to 9 cm long and 8 mm in diameter; rachis glabrous or sparingly pilose; bracts lanceolate to ovate-lanceolate, 7-15 mm long, about 4 mm wide, ciliate, 3-5-nerved, closely imbricate, acute and ending in a spine 0.5 mm long; corolla bilabiate, 1 cm long, white to deep yellow with occasional purplish markings, a slender tube topped with lips 5 mm long; upper lip entire, lower lip 3-lobed. Fruits: Capsule 4.5 mm long, pubescent or glabrate; seeds papillose. Ecology: Found on dry open ground, slopes, and along arroyos and washes from 3,000-5,000 ft (914-1524 m); flowers September-June. Distribution: Southern AZ to the south through Mexico and Central America to northern South America and the Galapagos. Notes: The most widely distributed and northernmost species in the genus. Distinctive by its sprawling habit and especially the elongated spikes with graduated, leafy, hairy bracts subtending beautiful 2-lipped, cream flowers with purple spots on the flared upper lips. Ethnobotany: People of the Yucatan used it to aid in childbirth. Etymology: Tetramerium is from tetras- four and meris- part, meaning four parts, while nervosum means having distinct veins or nerves, referring to the nerves on the bracts. Synonyms: Tetramerium hispidum, Tetramerium nervosum var. hispidum Editor: SBuckley 2010, FSCoburn 2015, AHazelton 2015