Page:An introduction to physiological and systematical botany (1st edition).djvu/172

 142 of the flower necessary to their perfection. So likewise the seeds of Mints, a tribe of plants which increase excessively by roots, have hardly been detected by any botanist; and it is asserted by Doody in Ray's Synopsis, that when the elegant little Ornithopus perpusillus, ''Engl. Bot. t.'' 369, does not produce pods, it propagates itself by the grains or tubercles of its root, though in general the root is annual.