52 



ANGIOSPERMAEDICOTYLEDONES 



1784. P. media Sw. (Kemer, 'Nat. Hist. PI.,' Eng. Ed. i, II.) Kerner says 

 that automatic self-pollination is brought about in the white flowers of this species by 

 a bending of the style, by which the stigma is brought into contact with pollen lying 

 in depressions of the petals. 



1785. P. secunda L. (Kemer, op. cit., p. 274 ; Ricca, Atti Soc. ital. sc. nat., 

 Milano, xiv, 187 1 ; Warnstorf, Schr. natw. Ver., Wernigerode, xi, pp. 7-8.) Kerner 

 says that in this species nectar is secreted at the base of the corolla in the pendulous 

 flowers. The anther-pores face upwards, and the S-shaped filaments are kept in 

 place by the petals. When a nectar-seeking insect touches the stamens the anthers 

 tip over, so that the pollen falls upon and dusts it. This pollen is then transferred to 

 the stigma of the next flower visited. 



Ricca describes the flowers as feebly protogynous, and Warnstorf also says they 

 are protogynous. During the first (female) stage of anthesis the thick glutinous 

 stigma projects about 2 mm. from the flower-bell, while the white pubescent anthers, 



borne on S-shaped fila- 

 ments, are first closed, 

 but afterwards dehisce on 

 the side turned inwards. 

 If the proboscis of an 

 insect is inserted into the 

 flower at this stage, the 

 anthers tip over and dis- 

 charge their mealy white 

 pollen on the head of 

 the visitor, to be trans- 

 ferred to the projecting 

 stigma of the next flower 

 visited. Should insect- 

 visits fail, the filaments 

 straighten themselves, and 

 the anthers project from 

 the flower, the opening of 

 which is widened by the 

 pressing back of the petals. 

 The anthers now tip over of their own accord, and the pollen is able to fall on 

 the stigmas of lower flowers. The pollen-grains are smooth, ellipsoidal, about 

 25 /A long and 12 /* broad. 



1786. P. uniflora L. (=Moneses grandiflora ^. F. Gray). (Ricca, Atti Soc. 

 ital. sc. nat., Milano, xiv, 1871 ; Herm. Muller, ' Alpenblumen,' pp. 375-6 ; Kerner, 

 ' Nat. Hist. PI.,' Eng. Ed. i, II, p. 383 ; Warming, Bot. Tids., Kjobenhavn, xv, 1895, 

 pp. 15-18 ; Lindman, ' Bidrag till Kanned. om Skandin. Fjellvaxt. Blomn. o. Befrukt.') 

 The large white nectarless flowers of this species are turned downwards, and as 

 they expand to a breadth of 20 mm. are tolerably conspicuous, though only one is 

 situated at the end of each peduncle. The lowest part of the flower is the most con- 

 venient alighting-platform, and this is constituted by the five sharp lobes of the] 



Fig. 232. Pyrola uniflora, L. (after Herm. Muller). A. Flower seen 

 directly from below (x 3). B. Pistil of same, seen from the side (x 3). 

 C. An anther ( x 7). gr, style ; ov, ovary ; st, stigma. 



