DIDYNAMIA. 127 



168. AJUGA. Upper lip minute, abrupt, notched; lower one 3- 

 lobed, the central largest, inversely heart-shaped ; stamens 

 exserted. 



174. BETONICA. Calyx teeth spinous-tipped ; upper lip of the 



corolla nearly flat, ascending, the lower 3-cleft ; tube cylin- 

 drical, incurved ; stamens not longer than the throat. 



172. L.AMIUM. Calyx teeth spinous, spreading; upper lip of the 



corolla vaulted, entire, lower 2-lobed, toothed at each side 

 of the throat ; anthers hairy. 



173. GALEOPSIS. Calyx teeth spinous-tipped ; upper Up of the 



corolla vaulted, serrated, lower in 3 unequal lobes, with a 

 pair of hollow prominences at the base in front. 



175. STACK vs. Calyx teeth spinous-pointed ; upper lip of the 



corolla vaulted, lower one 3-lobed, the lateral lobes reflex- 

 ed ; stamens finally spreading outwards at each side. 



176. BALLOT A. Calyx with 10 ribs and 5 teeth; upper lip of 

 *the corolla concave, notched : lower 3-lobed, obtuse, the 



central lobe largest, cloven. 



177- MARRUBIUM. Calyx with 10 ribs and 10 spreading teeth ; 

 upper lip of the corolla straight, linear, cloven : lower in 3 

 deep lobes, the middle one largest and cloven. 



* * Calyx two-lipped. 



181. SCUTELLARIA. Calyx, when in fruit, closed by a dorsal 

 lid. 



180. THYMUS. Calyx closed with dense converging hairs. 



178. CLINOPODIUM. Calyx many-ribbed; involucrum of nume- 



rous taper leaves under the flowers. 



179. ORIGANUM. Calyx without ribs ; involucrum of numerous 



dilated flat leaves, 1 to each flower, collected into a spu- 

 rious catkin. 



