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 g-lobed... 20002... .2e. 2 2% 
Ovary deeply. 4-parted.... 2:25) 129.2 ee DISS ae ate een 32 
9,~ Corolla ‘very irregular. 2: 0) U 29s ee Teucrium p. 273 
Corolla nearly regular... si) we fee Isanthus p. 274 
3. Calyx with a conspicuous hump on upper side. Scutellaria p. 275 
Calyx without a hump on upperside... ....-...5:. eee ee 4 
4. . Corolla nearly resularc:: <2 ee errr yr a 
Corolla '2-lipped oy... 060 5 ics «'s,2g daha ie 2 6 
Corolla with 4 equal lobes and a fifth pendant. Collinsonia p. 292 
5. Stamens 2; plants not fragfant.............. Lycopus p. 290° 
Stameiis 4} platits fragrant... 2.0: : se eee Mentha p. 291 
Stamens 4; plants ill smelling; foliage purple....Peril/a p. 292 
6. Stamens 2.2.00... 5 nck. ue oo be 72 
Stamens 4... 40.00.00 280 oie te ee ee 9 
7. Upper lip of corolla flat or nearly so........ Hedeoma p. 288 
Upper lip of corolla concave.........-. . 2). See 8. 
8. “Calyx nearly equally: 5-toothed::)..:.. ?222% Monarda p. 285 — 
Calyx -e-lipped:: 42 2s oh eee .Blephilia p. 287 
sg. Upper lip of corolla flat or nearly so...... Pycnanthemum p. 289 
Upper lip of corolla concave j..:¢ 4:2 s+. ...g 10 
fo.iCalyx teeth stiff and spiny:3\irv,ts,. cps ed eeee Leonurus p. 283 
Calyx teeth not spiny i, 2235 ..doeen . te lia 
ri, Flowers greenish yellow. ..2 . 2.2% oases Agastache p. 277 
Flowers not greenish yellow....... eer me 12 
227, EPlowers about 1 inch long... .. 5: eos eee Physostegia p. 281 | 
Blowers shorter. 2. 2.00 0. 0. ode Soe ee oa 
ia. Léaves sessile or hearly so... 2.22) ee ee Stachys p. 284 
Reaves petioled. 0. ee a 14 
ia. ke alyx% nearly equally s-toothed 3.7.5). 34.2 eeee Nepeta p. 278 
Roayx 2-lipped | cshoiy Pea oe ee ee Prunella p. 280 
