404 MEIOTAXY IN 



corolla is developed as usual. This deficiency of the 

 corolla is frequently, but not invariably, associated 

 with an increased fertility. Thus, in some violets the 

 flowers produced in summer, and in which the petals 

 are either entirely suppressed or are more or less 

 atrophied, are always fertile, while the blossoms deve- 

 loped in spring, and in which the petals are always 

 present, are much less fertile. In Oxalis Acetosella 

 there are two forms of flower, the one with, the other 

 without, petals, but both seem equally fertile. Linne 

 remarks that many plants which, in warm latitudes, 

 produce a corolla, do not do so when grown in colder 

 chmates. Thus, certain species of Helianthemum are 

 apetalous in Lapland. In the Pyrenees, according to 

 Bentham, the flowers of Ajuga iva are constantly de- 

 prived of their corolla.^ 



Apetalous flowers have been noted most frequently 

 in the follo^ving plants : 



Aconitum, sp. pi. I Crataegus ! 



Cardamine impatiens. Medicago lupulina. 



Clieiranthus Cheiri I Melilotus officinalis. 



Viola odorata ! Ononis minutissima. 



(Jerastium vulgatnni I Saxifraga longifolia, 



Alsine media. Verbascum Thapsus. 



Stellaria. Ajuga iva. 



Lychnis dioica ! Teiicriura Botrys. 

 Dianthus barbatus, and othex' Lamium purpui-eum ! 



Caryophyllea;. amplexicaule. 



Helianthemum, sp. I Polemonium cseruleum. 



Oxalis Acetosella. Campanula, sp. pi. ! 



Balsamiuca?. Ruellia clandestina. 



Malpighiacea?. Lonicera Periclymenum ! 



Rosa centifolia. Ti-adescantia, sp. ! 



arrensis I Hymenocallis. 



The following references apply some to apetalous and others to dimor- 

 phic flowers, but it must be remembered that the latter plants are not 

 necessarily wanting in petals or stamens, &c., though the functional 

 activity of the parts may be impaired : 



A. de Jussieu, ' Monogr. Malpigh.,' pp. 82, 334. Ton-ej , ' Fl. New 

 York,' i, p. 428. Hooker and Thomson, ' Joum. Linn. Soc.,' ii, p. 7. 

 Guillemin, ' Archiv de Botan.,' i, p. 412. Michalet, ' Bull. Soc. Bot. 

 Fr.,' vii, p. 465. Midler, * Bot. Zeit.,' 1857, p. 729. Natural History 

 Review,' July, 1862, p. 235. 



Cat. Plant. Pyr,' p. 58. 



