MINT FAMILY LABIATAE 



This large and well-known family, with probably 3500 

 species, is represented in Illinois by many wild flowers and a 

 smaller number of garden blooms. There are no poisonous 

 species. The leaves, which are always opposite and simple, are 

 in all species dotted with transparent oil sacs that mark the 

 family's economic importance. A variety of volatile oils from 

 these sacs are extensively used in mint candies, chewing gum 

 and medicine. 



Most members of the family are characterized by square 

 stems and conspicuous flowers with irregular corollas, deeply 

 4-lobed ovaries and 2 or 4 stamens, but there are several 

 exceptions. 



KEY TO GENERA 



1. Ovary merely 4-lobed 2 



Ovary deeply 4-parted 3 



2. Corolla very irregular Teucrium p. 273 



Corolla nearly regular Isanthus p. 274 



3. Calyx with a conspicuous hump on upper side . Scutellaria p. 275 

 Calyx without a hump on upper side 4 



4. Corolla nearly regular 5 



Corolla 2-lipped 6 



Corolla with 4 equal lobes and a fifth pendant . Collinsonia p. 292 



5. Stamens 2; plants not fragrant Lycopus p. 290 



Stamens 4; plants fragrant Mentha p. 291 



Stamens 4; plants ill smelling; foliage purple. . . .Perilla p. 292 



6. Stamens 2 7 



Stamens 4 9 



7. Upper lip of corolla flat or nearly so Hedeoma p. 288 



Upper lip of corolla concave 8 



8. Calyx nearly equally 5-toothed Monarda p. 285 



Calyx 2-lipped Blephilia p. 287 



9. Upper lip ot corolla flat or nearly so Fycnanthemiim p. 289 



Upper lip of corolla concave 10 



10. Calyx teeth stiff and spiny Leonnrus p. 283 



Calyx teeth not spiny 11 



11. Flowers greenish yellow . .Agastache p. 277 



Flowers not greenish yellow 12 



12. Flowers about i inch long Physostegia p. 281 



Flowers shorter 13 



13. Leaves sessile or nearly so Stachys p. 284 



Leaves petioled 14 



14. Calyx nearly equally 5-toothed Nepeta p. 278 



Calyx 2-lipped Prunella p. 280 



272 



