248 BOTANY [CHAP. X 



Letter 581 a tempting invitation from Daubeny l to meet Henslow, etc., 

 but upon the whole, I believe, lodgings will answer best, for 

 then I shall have a secure solitary retreat to rest in. 



I am extremely glad I sent the Laburnum:* the raceme 

 grew in centre of tree, and had a most minute tuft of leaves, 

 which presented no unusual appearance : there is now on one 

 raceme a terminal bilateral [i.e., half yellow, half purple] 

 flower, and on another raceme a single terminal pure yellow 

 and one adjoining bilateral flower. If you would like them 

 I will send them ; otherwise I would keep them to see whether 

 the bilateral flowers will seed, for Herbert 3 says the yellow 

 ones will. Herbert is wrong in thinking there arc no some- 

 what analogous facts : I can tell you some, when we meet. 

 I know not whether botanists consider each petal and stamen 

 an individual ; if so, there seems to me no especial difficulty 

 in the case, but if a flower-bud is a unit, are not their flowers 

 very strange ? 



I have seen Dillwyn in the Gardeners Chronicle, and was 

 disgusted at it, for I thought my bilateral flowers would have 

 been a novelty for you. 



In a letter to Hooker, dated June 2nd, 1847, Darwin makes a bold 

 suggestion as to floral symmetry : 



I send you a tuft of the quasi-hybrid Laburnum, with two 

 kinds of flowers on same stalk, and with what strikes [me] as 

 very curious (though I know it has been observed before), 



1 Charles Giles Bridle Daubeny, F.R.S. (1795-1867), Fellow of 

 Magdalen College, Oxford ; elected Professor of Chemistry in the 

 University 1822 ; in 1834 he became Professor of Botany, and in 1840 

 Professor of Rural Economy. 



2 This refers to the celebrated form known as Cytisus Adami, of which 

 a full account is given in Variation of Animals and Plants, Vol. I., Ed. II., 

 p. 413. It has been supposed to be a seminal hybrid or graft-hybrid 

 between C. laburnum and C. purpureus. It is remarkable for bearing 

 "on the same tree tufts of dingy red, bright yellow, and purple flowers, 

 borne on branches having widely different leaves and manner of growth." 

 In a paper by Camuzet in the A?males de la Socitte d } Horticulture de 

 Paris, XIII., 1833, p. 196, the author tries to show that Cytisus Adami is 

 a seminal hybrid between C. alpinus and C. laburnum. Fuchs (Site. k. 

 Akad. Wien, Bd. 107) and Beijerinck (K. Akad. Amsterdam, 1900) have 

 written on Cytisus Adami, but throw no light on the origin of the hybrid. 

 See letters to Jenner Weir in the present volume. 



3 Dean Herbert. 



