214 American Midland Naturalist Monograph No. 7 



3. Stamens long-exserted and strongly upcurved ; calyx with 3 long and 



2 short teeth 4. Trichostema 



2. Leaves serrate, crenate, or pinnatifid. 



4. Fertile stamens 2; plants inodorous 28. Lycopus 



4. Fertile stamens 4; plants strongly aromatic 29. Mentha 



1. Corolla very irregular (strongly zygomorphic) . 



5. Calyx with a small crest or callosity on the upper side, 2-lipped; stamens 



4 5. Scutellaria 



5. Calyx not crested. 



6. Flowers in compact axillary whorls, or in terminal heads or capitate 

 clusters. 



7. Bracts broad, conspicuous; corolla 2-5 cm long; flowers in dense 

 head-like clusters; calyx tubular, equally 5-toothed, 15-nerved; 



stamens 2 21. Monarda 



7. Bracts smaller or absent; corolla shorter. 



8. Stem corymbosely branched, stiffly erect; flower-heads clustered; 

 lea\es linear, lanceolate, or ovate; calyx nearly regular, 5- 



toothed, 10- to 13-nerved 26. Pycnanthemum 



8. Stem simple or with few branches. 



9. Calyx with 10 recurved teeth; corolla white, 5-6 mm long; 



leaves ovate, petioled, crenate, rugose; stem canescent 



6. Marrubium 



9. Calyx with fewer than 10 teeth. 

 10. Anther-bearing stamens 4. 



11. Corolla blue, apparently unilabiate, the upper lip short, 

 truncate; calyx 10- to many-nerved; ovary not deeply 



lobed 2. Ajuga 



11. Corolla bilabiate; ovary deeply 4-lobed. 

 12. Calyx not 2-lipped, the 5 teeth equal. 



13. Stamens conspicuovisly exserted beyond the 



corolla 7. Agastache 



13. Stamens not conspicuously exserted. 

 14. Calyx-teeth rigid, spine-tipped. 



15. Leaves lobed 14. Leonurus 



15. Leaves not lobed 15. Galeopsis 



14. Calyx-teeth not spine-tipped. 



16. Calyx 15-nerved; corolla 8-10 mm long, 



white with purple dots 8. Nepeta 



16. Calyx about 5-nerved; corolla purple, 12- 



24 mm long 16. Lamium 



12. Calyx 2-lipped, the teeth conspicuously unequal. 

 17. Stem erect or ascending. 



18. Leaves entire or sparingly crenate; floral 

 bracts ciliate; calyx reticulate-veiny, some- 

 what 10-nerved 13. Prunella 



18. Leaves coarsely sharply serrate; floral bracts 



pectinate; calyx 13- to 15-nerved 



1 1. Dracocephalum 



17. Stems prostrate, the flowering branches erect or 

 ascending, pubescent; leaves oval, obtuse, 

 entire, short-petioled, 6-15 mm long; corolla 

 purplish 25. Thymus 



