876 AUTOGAMY. 



Pedicularis incarnata (see fig. 306), a species which grows abundantly in Alpine 

 meadows. The flowers of this plant are arranged in spikes, and their development 

 proceeds from below up'wards (fig. 306 ^). The corolla is bilabiate; the lobes of the 

 under lip are at first upturned (see fig. 306 ^), but subsequently are expanded in a 

 slanting plane (figs. 306 * and 306 ^). The upper lip is helmet-shaped and rolled into a 

 tube at the apex (figs. 306 ^- ^' *> ^' ^' ''). The stamens are of the sugar-tongs type, and 

 their anthers are concealed underneath the arch of the upper lip (figs. 306 ''5''), 

 The long style is bent at an angle to correspond to the form of the upper lip; its 

 anterior extremity passes through the tube and rests in front of the orifice and at 

 the same time in front of the entrance to the floral interior. The humble-bees which 

 make use of this entrance are obliged to rub against the stigma, and if they come 

 laden with pollen from other flowers cross-fertilization ensues. Owing to the fact 

 that the flowers are protogynous insect- visitors cannot, in the first stage of bloom 

 (figs. 306 ^ and 306 ^), carry off any pollen, but can only leave behind upon the stigma 

 what they have brought with them; at later epochs, however, the insects, though 

 still brushing first against the stigma, are next moment besprinkled with the mealy 

 pollen which falls from the anthers in consequence of the disturbance of the tongs- 

 like stamens. Under the galeate arch of the upper lip there is a slit (fig. 306 *) to 

 allow the pollen to fall freely, and whenever an insect enters between the under and 

 upper lips this gap is enlarged. The head is the part of the humble-bee that 

 receives the pollen, and the latter may, of course, then be conveyed to other flowers. 

 If no insects visit a flower, the pollen remains for rather a long time dormant in the 

 anthers; but, in the last stage of bloom, the filaments become flaccid and give way, 

 and the pollen then falls of itself upon the edges of the slit. At the same time the 

 upper lip undergoes a marked downward bending (fig. 306 ^), wherebj^ that part of 

 it which is prolonged into a tube, is brought into a vertical position, so that the 

 pollen rolls down it, and is directed on to the stigma, which hangs right in front of 

 the mouth of the tube (fig. 306 '). Sometimes the stigma is drawn into the tube in 

 the process of bending above referred to and sticks there, like a cork in the neck of 

 a bottle; in which case self-pollination takes place inside the tube. Autogamy of 

 the type exhibited in Pedicularis incarnata occurs with slight variations in all 

 species which have the upper lip of the corolla produced into a tubular beak. The 

 cases of this kind especially subjected to investigation were Pedicularis asplenifolia, 

 P. Portenschlagii, P. rostrata, and P- tuberosa. 



Very different behaviour is observed in several species of the same genus in 

 which the upper lip has the form of a cowl or a helmet truncated in front, as, for 

 example, Pedicularis CEderi, P. foliosa, P. comosa, and P. recutita. Of these we 

 will take for illustration Pedicularis CEderi, which grows abundantly in Alpine 

 meadows in the neighbourhood of the Brenner Pass in Tyrol. As regards the con- 

 struction of its flowers, this species diff'ers from P. incarnata in that the stigma is 

 stationed in front of the truncated helmet forming the upper lip, and also in havmg 

 projecting ribs on both sides of the corolla, which act like a system of levers in 

 causing the inflection just before the flower fades. The entire upper lip at this 



