188 FERTILIZATION OF SPRING FLOWERS ON THE YORKSHIRE COAST. 



flowers of classes A, AB, B, and B', also that the early spring flora 

 of the Yorkshire coast is much more dependent on them for cross- 

 fertilizatiou than the same species in Belgimn and Germany. To 

 be dependent on less-specialized insects is in itself a disadvantage, 

 and added to this must be the risk of inclement weather. If it be 

 true, and there are as yet no facts to disprove it, that Copsella has 

 its stamens aborted by reason of the cold, then we ask what gain 

 comes to it by flowering early. Fumunculus Ficaria is so generally 

 infertile, Pctasites vuhjaris so uniformly male, and Ulex and Primula 

 set so little fruit — the former none from its early flowers — that 

 they too do not seem to profit by their early flowering. If we ask 

 how the species of the spring flora are propagated, we find that very 

 few are annuals and must set seed at frequent periods or perish, and 

 that others have a very considerable amount of vegetative repro- 

 duction, or are shrubs and trees which by their longevity can afford 

 only to fruit at intervals of some years. This, however, does not 

 explain what advantages they gain by flowering early. 



We should note here the length of the flowering period of the 

 l^lants. In some cases it is of short duration — e. g. Tiissilago, Sitlix, 

 Anemone, Priwula, Pianimcidus Ficaria, Prttnus, &c., in others much 

 protracted, so that, if the spring flowers go unfertilized, the summer 

 ones yet afibrd the species another chance of setting seed ; such are 

 Bcllis, Capsdla, and some others, which for this reason are not ex- 

 clusively spring plants. Of the exclusively spring flora we note that 

 many are trees or shrubs — i. e. Salix spp., Ulcx europmis, Prunus 

 communis, Corijlm, Aliius, Uhnus, and Populus ; and many are plants 

 which frequent shady places — i. e. Anemone nemorosa, Chnjsosplenium 

 oppositifoliuvi, C. alternifoHum, Adoxa, PotentUla Fragariaslrum, 

 Viola odorata, V. canina, Lathrcea Sguamaria, Nepeta Glcchoma, 

 Primula ruh/aris, and Narcissus Pseudo-narcissus, besides the wind- 

 fertilized il/erc'((;-m//s ^>tvv?r»/s ; several others are found, sometimes 

 among bushes, sometimes in the open ; while but a small minority 

 — Alchemilla arvensis, I'hiipetrum ni[/ruin, Cuciilcaria officinalis, Vero)iica 

 arcensis, and Tussilaqo — grow almost always where they get the full 

 sun. On this we may found a fair hypothesis by which we can under- 

 stand in part the early flowering of species. The key to the situation 

 lies in the early flowering of the anemophilous trees. These can suffer 

 from no competition for insect-visitors, and if it is advantageous to 

 them to flower early, it must be for some other reason. Many 

 certainly do flower early, and no better explanation could be desired 

 than that given by Clarke* and Eobertsonf , namely, that the leaves 

 would hinder the passage of the pollen from anther to stigma, not 

 only by barring the way, but by preventing the wind from reaching 

 the flowers. In the case of shade-loving entomophilous flowers the 

 cause is the same — the insects would be prevented from seeing the 

 bright colours by the mask of green leaves. There is little doubt 



* " The Philosophy of Flower Seasons," .Jhi. A^afMra?/.*?, xxvii.p. 769 (1803). 



t " The PhilosoiDhy of Flower Seasons, and the Phajnological Eelations of 

 the Entomophilous Flora and the Anthophilous Insect-Fauna.'' Am. Naturalist, 

 xxix. p. 97 (1895). 



