2IO ANGIOSPERMAE—DICOTYLEDONES 



2150. P. Oederi Vahl. ( = P. flammea Oed.) (Warming, Bot. Tids., Kjobenhavn, 

 xvii, 1890, p. 204.) — Warming says that the mechanism of the yellow or whitish- 

 yellow flowers of this northern species agrees in general with that of P. recutita. 

 The tip of the upper lip is coloured dark-red inside. The corolla-tube is 20 mm. 

 long, and possesses a groove running inwards from the middle of the lower lip, as in 

 P. recutita. This does not serve, however, to conduct the proboscis of the insect 

 visitor, which is inserted into a cleft above it, formed by the close approximation of 

 the edges of the upper lip. The stigma generally projects from the upper lip, so 

 that it is first touched by a humble-bee visitor, and pollinated if this comes from 

 another flower. Autogamy, however, often takes place, for the style is not in- 

 frequently much shorter, not even attaining the level of the anthers. 



Visitors. — Lindman observed several humble-bees. 



2151. P. Oederi A. Kern. (= (?) P. flammea Wul/.). (Kerner, ' Nat. Hist. PI.,' 

 Eng. Ed. I, II, pp. 376-7.) — This species is common on the Brenner in the Tyrol, 

 and Kemer says that the stigma projects in front of the truncated upper lip. The 

 corolla is strengthened by characteristic ribs, which act like a system of levers, and 

 depress the upper lip until at last it is sharply bent down. This movement, of 

 course, involves the style contained in the upper lip, so that the stigma is brought 

 below the anthers instead of being placed above them. At the same time the closely 

 apposed anthers are separated, sprinkling the stigma with pollen. As in P. recutita, 

 crossing is only possible at the beginning of anthesis. 



2152. P. foliosa L., and 2153. P. comosa L. These possess a flower 

 mechanism similar to that of the last species. 



2154. P. incamata Jacq. (Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 375.) 

 — In this species the anthers are concealed in the upper lip, which is bent at right 

 angles, while the style projects from it, bringing the stigma into the entrance of the 

 flower, so that it must first be touched by visiting humble-bees. As, too, it matures 

 before the anthers, only cross-pollination can take place in this first stage of anthesis. 

 Later on, after dehiscence has taken place, pollen is sprinkled on the heads of insect 

 visitors. Should insect-visits fail, the stamens become limp during the last days of 

 anthesis, the anthers separate, and pollen falls on the inner surface of the tubular 

 bent upper lip. At the same time this becomes more strongly flexed into a vertical 

 position, and the pollen falls down on to the stigma which is placed immediately 

 below. Sometimes as the upper lip is undergoing these changes in position the 

 stigma is drawn into it, and autogamy is effected within its tubular part. Kerner 

 states that a similar mechanism for effecting self-polHnation exists in P. asplenifolia 

 Floerke, P. Portsnschlagii Saul,, P. rostrata Z., and P. tuberosa L. 



2155. P. rostrata L. (Ricca, Atti Soc. ital. sc. nat., INIilano, xiii, 1870; 

 Herm. Miiller, ' Alpenblumen,' pp. 298-300; Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, 

 II, p. 272.) — Hermann Miiller says that the lower lip is obliquely disposed in this 

 species, as in P. sylvatica. The anthers are concealed in the vaulted upper lip, and 

 cannot be directly touched by visitors. These are humble-bees, which Kerner says 

 separate the filaments when they force their way into the flowers, so that the smooth 

 anthers are forced apart and pollen is sprinkled on their heads. Automatic self- 



