304 THE CROSSING OF FLOWERS. 



flower, although previously only the stigma would have been brushed in the same 

 position. 



In a second group, to which belong many Gentians {Gentiana asclepiadea 

 ciliata, Pneumonanthe), most Malvaceae (Abutilon, Malva), the numerous species 

 of Monkshood (Aconitum), Funkia, and the Red Valerian (Centranthus), the pollen 

 in a young flower is exposed close to the path of the honey-seeking insect; some- 

 times only from a single anther (as in Centranthus, figs. 289 ^■^'^), sometimes from 

 five or six, or from quite a number united together in one bundle (Malvaceae). The 

 stigmas are at first hidden behind, i.e. below the anthers; later on the anther- 

 filaments bend back in a semicircle, and the stigmas are exposed. When only a 

 single stigma is present (hitherto hidden behind the anther as in Centranthus) of 

 course only one can be displayed (see figs. 289 ^ and 289 ^). When an insect comes 

 for honey it strikes against the exposed stigmas, just as it did previously against 

 the anthers. 



The third group contains species of Gladiolus, Acanthus, Penstemon, and Sage 

 (Salvia; see fig. 271, p. 262). The styles and stigmas of the horizontally-directed 

 flowers of these plants lie close against the roof -like portion of the corolla above the 

 anthers, but later the style bends down until the stigma lies just in the path which 

 leads to the honey, so that insects passing this way (laden with pollen from the 

 younger flowers) deposit it in older ones, so producing cross-fertilization. 



In the fourth group, to which belong the genera Allionia and Phalangium, the 

 stigma at the commencement of flowering is at the end of the projecting style in 

 front of the anthers, and insects flying to the flowers are obliged to brush against 

 this stigma. Afterwards the style bends sideways through an angle of 80-90°, so 

 that the stigma is removed from the road leading to the honey. Now, when insects 

 fly to the flower they come in contact with the pollen-covered anthers only. 



In flowers of the fifth group, of which the Germander (Teucrium; see figs. 

 289 *■ ^ ^) is a type, the change of position resembles that of Centranthus in that the 

 thread-like anther-filaments are placed at the aperture of the flower, so that insects 

 strike against the anthers as they enter. Afterwai-ds the stamens bend up, and the 

 anthers are removed from the path, whilst concurrently the stigmas are exposed. 

 But there is this important difference — in the Germander the style as well as the 

 stamens alters its direction and position and bends downwards like a bow till the 

 stigmas come to lie in exactly the same position as was previously occupied by the 

 anthers. 



In the flowers of the sixth group, typical examples of which are furnished by the 

 sweet Basil {Ocymum Basilicum) and the well-known climber, Gobcea scandens, the 

 same kind of change of position occurs as in the Germander; but the stamen-fila- 

 ments bend down instead of up, and the style upwards instead of downwards. At 

 the beginning of flowering the anthers intercept the passage to the honey at the 

 base of the flower, but later on they sink downwards, while the style arches up, 

 bringing the stigma to the identical place previously occupied by the anthers. 



The remarkable change of position of stigmas and anthers in plants of the 



