LENTIBULARIACEAE 235 



Heinsius says that the stigma is blunt and beset on the upper margin with stiff 

 hairs, which act as combs to draw the pollen-grains out of the visitors' hairs when the 

 lobe folds up. These grains then adhere to the upwardly-directed stigmatic papillae. 

 It is particularly easy for the pollen-grains to be combed out of the insects' hairs, for 

 they are provided with numerous meridional furrows, making them easy to seize. 



A complicated flower mechanism such as that described can as a rule only be 

 operated by bees. Heinsius, however, has also noticed hover-flies. They alight on 

 the lower lip and push against the upper one until the former is pressed down and 

 the entrance to the nectar exposed. They suck for some seconds, and then go to 

 another flower of the same species. Helophilus lineatus F. (in large numbers) and 

 Rhingia campestris Mg. (occasionally) behave in this way. Heinsius deduces from 

 his observations that long-tongued hover-flies are the normal pollinators, and thinks 

 that, the mouth of the flower being too narrow for most bees, there can be no 

 question of visits from them. He adds — ' It may be seen from this, that the hover- 

 flies mentioned have reached such a high stage of mental development that they can 

 find the way into a completely closed flower.' 



Visitors. — Vide supra. 



2191. U. major Schmedel (=U. neglecta ZM;«.).— Buchenau says that the 

 mechanism of this species agrees with that of the preceding one. 



2192. U. minor L. ( = U. Bremii Heer). — Buchenau describes this species as 

 possessing a small, blunt, conical spur projecting at right angles to the axis of the 

 flower. And vide next species. 



2193. U. ochroleuca R. Hartm. (Abromeit, ' Bot. Ergeb. v. Drygalski's Gron- 

 landsexped.,' pp. 41-2.) — Vanhoffen only observed sterile plants of this species in 

 Greenland, as did Hartz, Berlin, and Kolderup-Rosenvinge in the case of U. minor L. 



680. Pinguicula Tourn. 



Flowers, blue or white, homogamous or protogynous, without a sensitive stigma , 

 and belonging to class Hb or Fpt. The lower lip serves as an alighting-platform. 

 The spur either secretes and conceals nectar in its base, or contains small, stalked, 

 capitate projections serving as food. 



2194. P. vulgaris L. (Sprengel, ' Entd. Geh.,' pp. 54-6 ; Warming, ' Arkt. 

 Vaxt. Biol.,' pp. 31 et seq. ; Axell, ' Om Anord. for Fanerog. Vaxt. Befrukt.,' 

 pp. 42-3; Hildebrand, Bot. Ztg., Leipzig, xxvii, 1869; Herm. Miiller, ' Alpen- 

 blumen,' pp. 354-5.) — The flowers of this species belong to class Hb. They are 

 horizontal, and of a deep blue colour. Nectar is secreted at the base of the long, thin, 

 downwardly-curved spur. The stigma lies below the bifid upper lip, and its large 

 lobes cover the anthers, which are immediately beneath it. The whole flower 

 mechanism, therefore, agrees with that of Utricularia, except that the stigma-lobes are 

 not sensitive. When a bee of the right size visits the flower, it touches first the 

 papillose lower stigma-lobe and dusts it with pollen should another flower have been 

 previously visited. On penetrating further into the flower, the bee's head and back 

 are dusted with fresh pollen : this, however, is not deposited on the stigma of the 

 same flower when the bee creeps back, because in doing so it forces the papillose 

 stigmatic lobe upwards. Insect-visits, therefore, ensure cross-pollination in this case, 



