32 A NEW ZEALAND NATURALISTS CALENDAR. 



plants it has a great range, being found on the coasts 

 both of temperate and tropical Australia and right 

 away to Europe. As a boy I can recall its occurrence 

 on the shores of the Firth of Forth. Its seeds are 

 probably capable of floating for a long time in sea-water 

 without being injured indeed, the plant will not, as far 

 as my experience goes, grow away from the neighbour- 

 hood of the sea and of salt water. I have never succeeded 

 in germinating the seed in ordinary soil, nor have plants 

 brought from the beach and placed in the garden border 

 ever survived. It is an example of a plant very greatly 

 specialised for the particular habitat in which it occurs. 

 Another plant which affects brackish lagoons and damp 

 spots is Mimulus repens, a low-growing small herb, 

 whose pretty purple flowers, with their yellow throat, 

 make it a conspicuous object. The most curious feature 

 noticeable about all species of Mimulus (the common 

 yellow musk is a good example) is the possession of a 

 two-lobed stigma, of which the lower lobe or plate is 

 sensitive. This is a feature they share with several other 

 plants belonging to the same natural order (Scrophu- 

 larinece). If you look into a flower of musk you will 

 see the little stigma like a small whitish disc at the 

 back of the flower facing you, and probably wide open. 

 Touch the lower plate or lobe with the point of a blade 

 of grass, and it will almost immediately close up. This 

 is one of the many devices which exist in brightly- 

 coloured flowers to bring about cross- and to prevent 

 self -fertilisation. If an insect thrusts its head into the 

 flower and touches this stigmatic plate it at once closes 

 up, but in the course of twenty minutes or so it opens 

 oiit again if no pollen has been placed on it. In with- 

 drawing from the flower the insect brushes out a 

 quantity of pollen from the anthers, but the stigma 

 being closed none of this can get on to their inner 

 surface. But the next flower which is visited receives 

 some of the pollen on to the lower lobe of the stigma, 

 which then closes up and does not open again. The 

 flower being thus pollinated and fertilised soon withers, 



