CUPULIFERAE 377 



of a bright yellow colour. In the male flowers, which are very numerous, and 

 enclosed in a bright yellow six-leaved perianth, the stamens are bent inwards at the 

 beginning of anthesis ; they straighten out later, each bearing at its upper end a bright 

 yellow anther, which is firmly bound to the filament. When the anthers dehisce, the 

 pollen does not scatter loosely, but remains lying upon them, in consequence of its 

 clinging properties. The pollen-grains are provided with three longitudinal grooves, 

 and often hang together in little clumps, although their extine is smooth and not 

 sticky with clinging drops of oil ; when dry, they are 19 /a long and 8 /i thick. 

 There is nothing, therefore, in the structure of the male inflorescence and flowers 

 which points with any probability to anemophily. As regards the female flowers, the 

 inconspicuousness caused by their green colour and the absence of any other means 

 of attraction would certainly indicate wind pollination, if it were not for the fact that 

 the immediate vicinity of the conspicuous fragrant male flowers bearing abundant 

 pollen obviates the necessity for display of colour or any other attraction in the 

 female ones. The structure of styles and stigmas is also quite different from that 

 of an anemophilous plant; the six styles of each flower are strong and stiff, with 

 a smooth shining surface. 



The entomophily of Castanea has been confirmed by direct observation. 

 Kirchner saw numerous pollen-collecting honey-bees and many species of flies as 

 well as small beetles visiting the flowers. There is no doubt that these insects, 

 which at first are only concerned with the obtaining of pollen, occasionally reach 

 the female flowers while creeping about the broad inflorescences, and deposit pollen 

 upon them. 



Visitors. The honey-bee was observed by Loew, Kirchner, and Knuth (po-cltg. 

 by the two latter). Kirchner also noticed flies and beetles, and Loew the AUeculid 

 beetle Cteniopus sulphureus Z. (freq. by Lake Como). 



803. Quercus L. 



Flowers anemophilous ; monoecious. Kerner (' Nat. Hist. PI.,' Eng. Ed. i, 

 II, p. 313) describes the oaks as protogynous, for the female flowers mature some 

 days before the male. Schulz (Ber. D. bot. Ges., Berlin, x, 1892) says that some 

 male flowers possess a fully-developed ovary instead of a vestige. He also observed 

 occasional vestiges of stamens in the female flowers of Q. sessiliflora Sm. 



2567. Q. sessiliflora Sm., and 2568. Q. Robur L. (= Q. pedunculata Ehrh.). 

 (MacLeod, Bot. Jaarb. Dodonaea, Ghent, vi, 1894, pp. 126-7.) MacLeod states 

 that these species possess the following mechanism. The flowers appear simul- 

 taneously with the foliage leaves. The thin, loose, interrupted S catkin consists of 

 a flexible axis bearing numerous flowers, each containing 5-8 stamens. The 

 5 flowers are arranged in groups of from i to 5, crowded in Q. sessiliflora, but more 

 loosely placed in Q. Robur, and consisting of a carpel with three stigmas. The 

 flexible J catkins are set in motion by the wind, and thus scatter the dry, powdery 

 pollen. 



804. Corylus L. 



2569. C.AvellanaL. (Sprengel,'Entd. Geh.,'p.432; Kerner, ' Nat. Hist. PI.,' 

 Eng. Ed. I, II, pp. 94, 148; Hildebrand, Jahrb. wiss. Bot., Leipzig, ii, 1871 ; 



