134 



INTRODUCTION 



D. Deceptive Flowers (Fd). 

 Parnassia palustris everywhere proves itself to be a Deceptive Fly Flower*. 

 Sprengel (' Entd. Geh,' p. 167) confesses that he finds the greatest difficulty in 

 interpreting the 'five sap-producing arrangements, which in alternation with the 

 stamens surround the pistil, and of which the structure is quite original and of its kind 

 unique.' We are indebted for a solution of the problem to Hermann MuUer, who 

 ('Alpenblumen,' p. 112) writes somewhat as follows : 'The yellow balls at the end of 

 ihe slender outgrowths from the staminodes resemble drops of fluid so completely 

 that we are obliged to convince ourselves by a special test that they are not such, 

 but that we have to deal with perfectly dry swellings. Parnassia palustris thus 

 appears to hold up to the view of the " stupid flies " some fifty ' drops of nectar 

 visible from afar, by which they are strongly attracted. When they approach, how- 

 ever, the flowers offer but a very modest 

 booty of exposed nectar, in comparison 

 to the prospect held out. In fact the " stupid 

 flies," i.e. the Muscidae, are everywhere the 

 chief visitors, for astuter insects perhaps 

 allow themselves to be deceived once, 

 but do not so readily return.' That this 

 interpretation is the correct one, is shown 

 by an observation of Hermann INIiiller, jun., 

 who, for a considerable time and from 

 no great distance, watched a hover-fly 

 (Eristalis nemorum), which is one of the 

 more sagacious Diptera, while it attempted 

 to lick these apparent drops, and it was 

 only frightened away by the closer approach 

 of the observer. 



Ophrys muscifera also appears to be 

 a Deceptive Fly Flower. Its purple-brown 

 velvety labellum, says Hermann Muller (Kosmos, ii, 1877, p. 335), with its pale-blue 

 naked spot, seems exactly as if made to entice, by its colour, flies with a taste 

 for decomposing material. Under favourable circumstances a broad median longi- 

 tudinal stripe on the labellum, which includes the pale-blue spot, is covered with 

 numerous little drops, that Hermann Muller saw a flesh-fly (Sarcophaga) licking. 

 The two shining black tubercles at the base of the labellum, that look like two 

 drops of fluid, are regarded by this investigator as pseudo-nectaries, which cannot 

 fail to tempt a fly that has approached to try to suck them, thus bringing about 

 the first act of cross-pollination. For as the insect stoops down to one of the 

 two pseudo-nectaries, it can scarcely fail to ^ouch with its head the projecting 

 rostellum, thus causing the adhesion of a pollinium, and when a few minutes later 



Fig. 49. Parnassia palustris, L., a Deceptive 

 Fly Flower. A. Flower after removal of three 

 sepals and four petals, seen exactly from above 

 (X 5). D. Staminode (highly magnified), n. 

 Nectar. 



* Cf. the note on Parnassia in Vol. II. 



^ In vigorous plants in the Meimersdorf Moss, near Kiel, Isaw each of the five staminodes 

 ornamented with about tw^enty-five balls, so that the flowers possessed as many as 125 apparent 

 nectar-drops. 



