1905-1906.] Some Rarer Plants of Gorebridge District. 265 



quires a longer life, and its flowers nominally endure for at 

 least eight days. It is a flower well worth an exact study. 

 It furnishes an example of movement of stamens. You know 

 its construction. Yellow sepals, tubular petals filled with 

 honey, then in successive whorls a multitude of stamens sur- 

 round the pistil. When the golden sepals have opened and 

 the bright colour has attracted the fertilising insect, the 

 anthers of the outermost whorl open to dehisce. But before 

 doing so their filaments have elongated, and twisted them- 

 selves round so as to bring the anthers exactly over the 

 mouths of the trumpet - shaped nectaries. When insects, 

 therefore, are sucking the honey, they brush against the 

 anthers, and carry away the pollen to fertilise the pistil of 

 another plant. Before another day has come round these 

 stamens have moved farther outward towards the sepals, and 

 the next innermost whorl have taken their place over the 

 nectaries ; and so on until all the whorls have occupied that 

 position. It is a wonderful provision, which, like the unusual 

 duration of the flowering- period, no doubt owes its existence 

 to the plant's great desire to perpetuate its species. The 

 Coronilla varia has a curious movement of its leaflets. By 

 day they lie expanded in the usual horizontal position. At 

 night the opposite leaflets close together like the two slices of 

 a sandwich. This is to prevent loss of heat by night-radia- 

 tion. Two other leguminous plants possess a wonderful sort 

 of piston apparatus by which they expel the pollen from their 

 anthers. A bee alighting on the wings of the flower presses 

 them down on the heel, and thereby pumps the pollen through 

 a hollow cone at the apex of the heel on to its belly or its 

 legs. It may have taken toll of the flower's honey, but in 

 return the flower compels it to perform the function of a 

 flower marriage. 



The Arum maculatum grows in Arniston Glen. All three 

 varieties are to be found there. That with the leaf a uniform 

 green, most numerous ; the variety with the black spots on 

 the leaves, about a third of the whole ; and the variety with 

 pale white spots is also represented. This is an interesting 

 plant. Tiny midges are the cross-fertilising agents, especially 

 the Psychoda phallanoides. In the cavity of a single spathe 

 hundreds of these insects may be found. The leaves are 



