120 PROTECTION OF POLLEN. 



and the anthers below them (see fig. vol. i. p. 742). Whilst thus suspended beneath 

 the scales the anthers open and the pollen rolls out. It is not,' however, imme- 

 diately blown away, but falls vertically and collects first of all in trough-like 

 depressions which occur on the external surfaces of the separate flowers. Here 

 it remains until there is dry weather and a pufl" of wind blows it away to the 

 stigmatic flowers, this being accomplished in a manner that will receive closer 

 consideration later on. Up to this moment its resting-place is sheltered from 

 rain and dew by the flowers situated above it on the same spike, and the 

 appendages of each flower thus constitute, on the one hand, a receptacle for the 

 pollen of the higher flowers, and on the other, a roof over the pollen which has 

 fallen upon the grooved backs of the lower flowers, as is shown in the illustration 

 representing the flowers of the Walnut already referred to. 



A special interest attaches to those flowers and inflorescences which assume 

 periodically an inverted position and whose stalks possess the faculty of bending, 

 stretching, or turning concomitantly with the alternations of day and night, and 

 of fine and wet weather. Such plants might quite properly be described as 

 weather-cocks. They include forms belonging to most widely different families, 

 but possessing the common attributes — first, that their flowers or inflorescences 

 are borne on comparatively long stalks, and secondly, that they offer their honey 

 and pollen to the flying insects which visit them in shallow cups or flat saucers, 

 or even on plane discs. In the daytime in fine weather when flowers and 

 inflorescences of this kind straighten out and turn their open surfaces towards 

 the sun, they are plentifully visited by such insects as refuse to enter pendent 

 bells and tubes from underneath, and only alight from above on wide, open, and 

 easily accessible flowers, and thus is effected the important function of pollen- 

 dispersion. On the other hand, by becoming pendent at night and in rainy 

 weather — i.e. at a time when insects are not commonly on the wing — they ensure 

 security for their pollen and honey against wet. Hence the periodic movement 

 of the axis appears to achieve a double advantage. 



In many Campanulaceae and Geraniacese it is the stalks of individual flowers 

 that bend. The widely-distributed species. Campanula patula and Geranium 

 Robertianum have been selected from the list of those orders for illustration 

 (c/. figs. 225^ and 225* with figs. 225^ and 225*). The same phenomenon occurs 

 in many species of Wood-sorrel, Poppy, Pheasant's Eye, Isopyrum, Crow-foot, 

 Wood Anemone, Cinquefoil, Starwort, Chickweed, Saxifrage, Eock-rose, Anoda, 

 Potato, Pimpernel, Jacob's Ladder, and Tulip (e.g. Oxalis lasiandra, Papaver 

 alpinum, Adonis vernalis, Isopyrum thalictroides, Ranunculus acris, Anemone 

 nemorosa, Potentilla atrosanguinea, Stellaria graminea, Cerastium chlorcefolium, 

 Saxifraga Huetiana, Helianthemum alpestre, Anoda hastata, Solanum tuberosum, 

 Anagallis phcenicea, Polemonium coeruleum, Tulipa sylvestris). In the Scabious 

 given in the illustration opposite (Scabiosa lucida, figs. 225^ and 225^), and in 

 several Composites (Bellis, Doronicwn, Sonchus, Tussilago, &c.) it is the peduncles 

 bearing the capitula which bend; in many Umbelliferous plants (e.g. Astrantia 



