THE BRYOLOGIST 



Vol. XXIV January, 192 i No. i 



ON THE DISPERSAL BY FLIES OF THE SPORES OF CERTAIN MOSSES 

 OF THE FAMILY SPLAGHNAGEAE ^ 



J. Bequaert 



During my stay in the Adirondacks last summer (1920) I had an opportunity 

 to observe on the summit of Mt. Skylight, above timberline, two species of 

 Splachnaceae : Tetraplodon mnioides B. & S., and T. angustatus B. & S.^ They 

 were growing on the droppings of some carnivorous mammal, among the sphag- 

 num of the boggy slopes. Both species are of course known to occur in the 

 Adirondack region, though the smaller of the two, T. angustatus, is said to be 

 much rarer than the other. The finding of these mosses, however, resulted in 

 an interesting ecological observation, quite new to me at the time and well 

 worth recording. 



The object of my trip to Mt. Skylight was primarily of an entomological 

 nature and, though I incidentally gathered some bryological material, the 

 Tetraplodons would probably have been overlooked had my attention not been 

 attracted by some small flies that flew up from one of the mosses as I was moving 

 in the bog. On closer examination of the object which these insects had left, 

 much to my surprise I found it to consist of a cushion of Tetraplodon mnioides 

 with abundant, bright brown-red fructifications. That this moss could be 

 attractive to flies struck me as most remarkable and I proceeded to watch the 

 plants more carefully. Soon some of the insects returned to the little moss- 

 cushion; alighting on the upper end of the capsules, they moved downward to 

 reach the upper part of the hypophysis, going from one capsule to another. 

 On approaching a hand lens as unobtrusively as possible, I could distinctly see 

 the flies passing the soft labella of their proboscis over the upper part of the 

 hypophysis, much like house-flies feeding on sugar, meat, or the perspiration 

 of human skin. It was thus quite evident that the flies visiting the hypophyses 

 of Tetraplodon lick up a secretion produced by that part of the plant. When 

 disturbed they fly off, rest a little distance away, and shortly return to the moss 

 capsules, so that the drawing power exercised on them by the hypophyses of 

 this Tetraplodon is by no means accidental. In alighting or in leaving, the 

 tiny creatures inevitably touch the spores at the mouth of the capsules, when 

 these are ripe and opened. Thus some of the spores become attached to the 

 hairs, the legs, or other parts of the flies and are eventually carried off by them. 



^ I am greatly indebted to my friend, Dr. W. H. Wiegmann, of New York City, for the identi- 

 fication of these mosses. 



The November number of The Bryologist was published February 8, 192 1. 



