478 



NATURE 



\Oct. lo, 1872 



ON The fertilisation of a few com- 

 mon PAPILIONACEOUS FLOWERS 



[NOTK TO Editor. — The enclosed paper was writlen in the 

 autumn of 1869, and then submitted to Mr. Darwin. With 

 his usual kindness he encouraged me to proceed with it ; 

 and with his usual thorougliness he advised me to make 

 it more complete than it is before giving it to the jniblic. 

 At the same time, he lent me various publications con- 

 t.iining articles on the subject of fertilisation, and, amoiig'^t 

 others, some by the Itali.an botanist, D;lpino, who has 

 done so much in this fic-ld. I found that he had in two 

 or three publications in the years 1S67 and lS58, anticipated 

 most of the observations contained in the accompanying paper ; 

 and I proposed to myself to attempt a nsinii} of what had 

 been done of lale years in the matter of fertilisation of flowers 

 by Delpino, Ilildebrand, and others. But this, though a 

 labour of love, is a greater labour than I can manage, ami 

 other calls have grown upon me. I therefore send the pajier 

 to you as it stands, begging that this note may be prefixetl in 

 order that I raay not be thought to be appropriating Delpin(j's 

 observations. — T. H. F., OcIoI'li- 1872.] 



A FTER reading Mr. Darwin's book on Orchids and 

 -'^ his papers on Lythnim and Primula, I made some 

 notes on the fertilisation of Phascolus and some of the 

 Camp.anulace;c, which had the good fortime to meet 

 with his approval, and which he had the kindness to send 

 lor publication to the Annals and IMagazine of Nattiral 

 History, where they appeared in October 1S68. The com- 

 parison of Phascolus with other Papilionaceous flowers led 

 mc to think that i\lr. Darwin's fertile ideas might receive 

 inany illustrations from the structure and functions of 

 this beautiful and interesting tribe ; and the following 

 are observations made during the summer of 1869 upon 



a few of the commonest of them. I am painfully con- 

 scious how imperfect want of time, of opportunity, and 

 of knowledge has left them ; and how many points there 

 are, even in these few flowers, which require a much 



more careful inquiry. Indcid, every new flower has its 

 own peculiarity ; and almost every new peculiarity suggests 

 the observation of facts in other flowers not previously 

 noticed ; so that the task is endless. Again it is difficult 

 to feel sure of a conclusion unless the whole process of 

 fertilisation by insects can be watched, and to a dweller 

 in towns, ignorant of insects and their habits, it is im- 

 possible. If, however, these observations should lead to 

 further inquiry and discussion, they may not be useless. 

 The flowers in question are Pis!nii sativum, several 

 species of Lm'/iynis, Vicia, and Phascolus, Robinia pseud- 

 Acacia, Wistaria, Onohrycliis saliva, Trifoliiim rcjwis 

 and T. pratensc, Lotus carniculatus, Lupiuus, Ouonis, 

 Aulhyllis, Ule.r, Genista, Sa>vtlia>uuus, and Cytisus. 



Pisum sativum, or Common Pea. — The blossoms are 

 generally two upon a common peduncle, and each 

 flower has a separate short pedicel (see Fig. i). Tlie 

 peduncle generally approaches the pcrpcndicul\r and 



(tnitui-e flower). 



maintains its position through the stages of bud, blos- 

 som, and pod, except that it gets stiffer. The short 

 pedicels, however, change their position twice. In the 

 bud they are bent down so that the base of the 

 calyx is uppermost, and the upper edge of the folded 

 vexillum lowest. In this stage the large calyx covers 

 with a weather-proof awning the tender blossom. As the 

 flower opens the pedicel straightens itself ; and when the 

 blossom is fully open it is quite straight, and at an angle 

 of 45° to the peduncle. The effect of this is to raise the 

 flower so that the keel and wings become almost horizon- 

 tal, whilst the showy limb of the vexillum, bent upwards 

 from the claw, displays a perpendicular face (see Fig. 2). 

 The wings are slightly attached to the keel at the base 

 of their limbs ; and the limbs project outwards and a 



calyx 



"hum s.Tli'i'ini! (lateral viaw of pistil and stAmiml tubs, w'ltli 

 irolla removed, and tenth stamen separated). 



little upwards in front of and above the keel, so as to 

 make an excellent lighting place for insects. The keel 

 IS boat-shaped, recurved at the apex, and the lower edges 



