g INTRODUCTION. 



flowers and closed bud-like bodies that never expand. 

 The latter resemble in this respect cleistogamic 

 flowers, but differ widely from them in being sterile 

 and conspicuous. Not only the aborted flower-buds 

 and their peduncles (which are elongated apparently 

 through the principle of compensation) are brightly 

 coloured, but so is the upper part of the spike 

 all, no doubt, for the sake of guiding insects to the 

 inconspicuous perfect flowers. From such cases as 

 these we may pass on to certain Labiatse, for instance, 

 Salvia Horminum, in which (as I hear from Mr. Thisel- 

 ton Dyer) the upper bracts are enlarged and brightly 

 coloured, no doubt for the same purpose as before, with 

 the flowers suppressed. 



In the Carrot and some allied TJmbelliferaB, the cen- 

 tral flower has its petals somewhat enlarged, and these 

 are of a dark purplish-red tint; but it cannot be sup- 

 posed that this one small flower makes the large white 

 umbel at all more conspicuous to insects. The central 

 flowers are said * to be neuter or sterile, but I ob- 

 tained by artificial fertilisation a seed (fruit) appa- 

 rently perfect from one such flower. Occasionally two 

 or three of the flowers next to the central one are simi- 

 larly characterised; and according to Vaucher f " cette 

 singuliere degeneration s'etend quelquefois a I'ombelle 

 entiere." That the modified central flower is of no 

 functional importance to the plant is almost certain. 

 It may perhaps be a remnant of a former and ancient 

 condition of the species, when one flower alone, the 

 central one, was female and yielded seeds, as in the 

 umbelliferous genus Echinophora. There is nothing 

 surprising in the central flower tending to retain its 



'The English Flora,' by Sir rope,' 1841, torn. ii. p. 614. On the 

 J. E Smith, 1824, vol. ii. p. 39. Echinophora, p. 627. 

 t ' Hist. Phys. des Plantes d'Eu- 



