56 HYBRID PRIMULAS. CHAP. II. 



Owing to the frequency of this intermediate hybrid 

 form, and to the existence of the Bardfield oxlip 

 (P. elatior), which resembles to a certain extent the 

 common oxlip, the claim of the three forms to rank 

 as distinct species has been discussed oftener and at 

 greater length than that of almost any other plant. 

 Linnaeus considered P. veris, vulgaris, and elatior to be 

 varieties of the same species, as do some distinguished 

 botanists at the present day; whilst others who have 

 carefully studied these plants do not doubt that they 

 are distinct species. The following observations prove, 

 I think, that the latter view is correct; and they fur- 

 ther show that the common oxlip is a hybrid between 

 P. veris and vulgaris. 



The cowslip differs so conspicuously in general ap- 

 pearance from the primrose, that nothing need here 

 be said with respect to their external characters.* 

 But some less obvious differences deserve notice. As 

 both species are heterostyled, their complete fertili- 

 sation depends on insects. The cowslip is habitually 

 visited during the day by the larger humble-bees 

 (viz. Bombus muscorum and hortorum), and at night 

 by moths, as I have seen in the case of Cucullia. The 

 primrose is never visited (and I speak after many 

 years' observation) by the larger humble-bees, and 

 only rarely by the smaller kinds; hence its ferti- 

 lisation must depend almost exclusively on moths. 

 There is nothing in the structure of the flowers of the 

 two plants which can determine the visits of such 

 widely different insects. But they emit a different 

 odour, and perhaps their nectar may have a different 

 taste. Both the long-styled and short-styled forms of 



* The Rev. W. A. Leighton seed, in ' Ann. and Mag. of Nat. 

 has pointed out certain differences Hist.,' 2nd series, vol. ii., 1848, p. 

 in the form of the capsules and 164. 



