396 
PHARMACEUTICAL BOTANY 
pentamerous, rarely tetramerous; sepals five, synsepalous, ribbed 
and forming a tubular regular or irregular bilabiate (Scullcap, etc.) 
calyx whose upper lip is bifid and lower trifid; corolla of five to four 
gamopetalous petals, hypogynous, frequently two-lipped, the upper 
lip bifid, the lower trifid; stamens four, didynamous, rarely one pair 
alone fertile and the other pair reduced, in some cases almost or 
I 
Fig. 231 .—Mentha piperita —’Flowering branch. (Sayre.) 
quite to disappearing point (Salvin and Monarda ); pistil bicarpellate, 
embryologically two-celled with two ovules in each cavity, becoming, 
at time of flowering, four-celled with one ovule in each cavity. Style 
embryologically terminal, but, upon opening of flower, deeply gyno- 
basic, elongate, slender with two stigmatic surfaces. Fruit four 
nutlets enclosing as many exalbuminous seeds. 
