II SCROPHULARIACE^ 311 



pollen brought from older flowers of another stock. 

 In America also, wasps are the special visitors of this 

 species. There appear, however, to be remarkable 

 difierences. Knuth, like Sprengel and other observers, 

 found the flowers in Holstein to be, at first, specially 

 attractive to wasps. Later in the season, however, 

 they were neglected by wasps, and much visited 

 by bees. Eobertson, in Illinois, confirms this, but 

 adds that the wasps gradually returned. It may be 

 possible that these difierences might be explained if we 

 knew what other plants were in flower at the same time. 

 Knuth remarks that the brown of the corolla and 

 the yellow anthers closely reproduce the colouring of 

 the wasps. JEpipactis latifolia, which is also a dingy 

 purple, is almost the only other British plant which is 

 visited by wasps. The plant is glabrous. 



S. aquatica. — The flower agrees in the main points 

 with that of S. nodosa. The stem is distinctly winged, 

 and the plant is glabrous. 



S. Scorodonia, on the other hand, is pubescent, or 

 sometimes hairy. It is a native of the West of England 

 and Kerry. 



S. vernalis. — A bee flower with a sweet smell. There 

 is no barren stamen. The anthers all project beyond 

 the corolla-tube. The plant is glandular-pubescent. It 

 is a rare plant, occasionally found in waste places, but is 

 not native. 



MiMULTJS 



Homogamous bee flowers with a sensitive stigma. 



M. luteus. — A native of North America, now 

 thoroughly naturalised in Britain. The pistil lies over 

 the stamens, and the bee first touches the stigma. This 

 has two sensitive lips which close over the pollen like 

 a forceps. If none is enclosed they reopen, ready for 

 another chance. 



' According to Edgeworth, M. moschatus has two 

 kinds of pollen. The seeds are brown, very minute, 

 biconvex and oblong or elliptical. 



