A new key to Trichostema section Trichostema: 1. Longest stem and node hairs three or more cells long; nodes with hairs primarily spreading, rarely also or only with hairs downwardly or upwardly curled; leaves widest towards the base or near the middle; longer style branch 1–2 times as long as the shorter (Trichostema dichotomum complex) ......................................................................................................................................2 - Longest stem and node hairs three or fewer cells long; nodes with hairs primarily downwardly curved to appressed, rarely also with hairs spreading or upwardly curled; leaves widest near the middle or towards the tip, or linear; longer style branch 2 or more times as long as the shorter.................................................................................................................................................................5 2. Plant annual, branching primarily from the middle to upper part of the plant; mid-stem hairs spreading, occasionally also downwardly or upwardly curled, longest spreading hairs five or more cells long (view at 40x); longest node hairs five or more cells long (view at 40x), spreading, rarely also upwardly curved; nutlet ridges distinct, steep sided, giving a clearly wrinkled appearance (view at 20x; see figure 2); widespread in eastern North America ............................................................. Trichostema dichotomum - Plant perennial, branching throughout the plant; mid-stem hairs downwardly curved, occasionally also spreading, longest spreading hairs 3–6 cells long; longest node hairs 3–6 cells long (view at 40x), spreading, rarely also or only downwardly curved; nutlet ridges fainter, shallow sided, giving a smoother appearance (view at 20x; see Figure 2); restricted to the outer coastal plain of North Carolina, South Carolina, Georgia, Florida, Alabama, and Mississippi .............................................................................................3 3. Older plants leggy, medium sized bushes to 1.25 meters tall; largest leaves 2.75–5.5 cm long, 0.75–1.75 cm wide; primarily inland with coastal populations in Alabama, Mississippi, Georgia, the Florida Panhandle, and Northeast Florida; not restricted to obviously calcareous substrates...................................................................................................................... Trichostema fruticosum - Older plants compact, small to medium sized bushes to 1 meter tall; largest leaves 1–3.5 cm long, 0.5–1.25 cm wide; primarily on barrier islands of North and South Carolina or Peninsular Florida; restricted to obviously calcareous (i.e., shelly or limestone) substrates ............................................................................................................................................................................................4 4. Largest leaves 1–2.3 cm long, 2–3 times as long as wide, often elliptic to rhombic; flowers lavender to white; anthers lemon yellow; along the coast of North and South Carolina ................................................................................... Trichostema nesophilum - Largest leaves 1.5–3.5 cm long, 2.25–3.75 times long as wide, often ovate; flowers varying shades of blue or blue-purple; anthers the same color as the upper petals; in peninsular Florida .............................................................................. Trichostema floridanum 5. Plant annual; largest leaves 2–5 cm long, 5–25 times long as wide; widespread in the Southeast.................. Trichostema setaceum - Plant annual or perennial; largest leaves 1–3.5 cm long, 1.5–9 times long as wide; restricted to Florida .........................................6 6. Plant annual, branching primarily in the middle and upper part of the plant; largest leaves 1.8–3.5 cm long; restricted to the Florida Panhandle .............................................................................................................................................................. Trichostema latens - Plant perennial, branching primarily near the base or throughout; largest leaves 1–2.5 cm long; restricted to the Florida Peninsula ............................................................................................................................................................................................................7 7. Largest leaves narrow, 3–9 times long as wide; nutlet ridges prominent, stocky, giving an intensely wrinkled or pockmarked appearance (view at 20x; see Figure 2) ..............................................................................................................................................8 - Largest leaves wide, 1.5–4.5 times long as wide; nutlet ridges faint to somewhat prominent, giving a smooth to slightly wrinkled appearance (view at 20x; see Figure 2) ..............................................................................................................................................9 8. Stem and node hairs primarily downwardly curved; largest leaves typically 1.5–2.5 cm long, 3.5–9 times long as wide; in mesic to scrubby flatwoods and scrub in the central to southern peninsula, not associated with the major ridge systems ............................... .............................................................................................................................................................................. Trichostema gracile - Stem and node hairs primarily spreading to upwardly curved; largest leaves typically 1.1–1.9 cm long, 3–5 times long as wide; in sandhill and sandhill-scrub ecotones on the Brooksville Ridge and areas west........................................ Trichostema microphyllum 9. Plant branching throughout; flowering October to January; restricted to Florida scrub near Stuart and Jupiter, Florida ................... ................................................................................................................................................................................. Trichostema hobe - Plant branching primarily near the base; flowering June to December; restricted to the large central ridge systems and associated ridge spurs (e.g., Mt. Dora Ridge, Lake Wales Ridge).....................................................................................................................10 10. Plant less robust, to 60 cm tall; leaves obovate, occasionally oblong to elliptic, very rarely ovate (5% of measured specimens); bract apices obtuse, occasionally ± 90° to rounded or acute, very rarely emarginate (5% of measured specimens); mature calyces 4.7–6.0 mm; on the Trail, Mt. Dora, and Orlando ridges and associated ridge spurs ................................ Trichostema suffrutescens - Plant more robust, to 1 meter tall; leaves obovate or oblong to elliptic, rarely ovate (20% of measured specimens); bract apices obtuse to rounded, occasionally ± 90° to acute, rarely emarginate (11% of measured specimens); mature calyces 5.2–6.2 mm; on the Lake Wales and Bombing Range ridges and associated ridge spurs .............................................. Trichostema bridgesii-orzellii

Published as part of Mcclelland, R. Kevan Schoonover, Weakley, Alan S. & Poindexter, Derick B., 2023, Seven new species of Trichostema (Lamiaceae: Ajugoideae) from the North American Coastal Plain biodiversity hotspot, pp. 95-149 in Phytotaxa 603 (2) on pages 129-130, DOI: 10.11646/phytotaxa.603.2.1, http://zenodo.org/record/8157972