THE ORCHID FAMILY 115 



and the pollen mass is shot out like an arrow against the back 

 of the entering bee, which carries it off to the female flower. 



Pollination of some New Zealand Species. 



The methods of pollination of some of the New Zealand 

 forms, have been described by Mr. G. M. Thomson and by 

 Mr. Cheeseman." It would appear from Mr. Thomson's 

 investigations, that several at least of our native orchids are 

 self-pollinated. Mr. Fitzgerald has shown in his " Australian 

 Orchids," that in the genus Thelyniitra all forms may be found 

 hetween plants which are regularly self-fertile and are never 

 cleistogamic, and those which are completely dependent upon 

 insects for pollination. The New Zealand Thelymitra longifolia 

 is a very puzzling case. It is one of the commonest of New 

 Zealand orchids. In the North Island it is almost everywhere 

 abundant except in the dense bush. In the South Island it is 

 hardly less common. According to Mr. Cheesemant " the 

 flowers usually open about nine o'clock in the morning, neatly 

 reclosing about four or five in the afternoon. There is, 

 however, considerable irregularity as to this, some varieties 

 only opening for a short time in the middle of the day, others 

 remaining expanded for a much longer period." On the other 

 hand, in the South Island, it is rare to find an open flower. 

 Even in fine weather not more than a few per cent, of the 

 flowers open properly. The chief reason why flowers do not 

 open in wet weather is that rain destroys their pollen ; many 

 of them therefore close in rain or adopt ingenious con- 

 trivances for keeping their pollen dry. Now, Mr. Cheeseman 

 has observed, {loc. cit.), that rain reduces the pollen of this 

 plant to a pulpy mass. This is perhaps the primary reason 

 for its closing. One would consequently expect to find it 

 more frequently opened in the drier climate of Australia, than 

 in New Zealand. However, observations seem to show the 



* Trans. Vol. V. p. 352, and Vol. XIII., p. 291. 

 t Trans. Vol. XIII., p. 293. 



