178 



THE FLOWER. 



superposed to) the sepals, and the stamens of the inner series 

 stand before the petals ; as in the diagram, Fig. 33 1. 1 



325. Flowers which completely 

 exemplify their type or symmetry 

 are rare, but most exhibit it more 

 or less. Each natural order or 

 group exhibits its own particular 

 floral type, or modification -of the 

 common type. 2 Some of these 

 modifications do not at all affect 

 the symmetry or obscure the plan 

 of the flower, except by combina- 

 tions which render the phylline 

 character of the floral envelopes and carpels 

 less apparent, such combinations being of 

 rare occurrence in foliage. Others gravely 

 interfere with floral symmetry, sometimes to 

 such degree that the true plan of the blossom 

 is to be ascertained only through extended 

 comparisons with the flowers of other plants 

 of the same order or tribe, or of related 

 orders. The symmetry of the blossom finds its explanation in 

 the laws which govern the arrangement of leaves on the axis ; 

 that is, in phyllotaxy. The deviations from symmetry and from 

 typical simplicity have to be explained, and in the first instance 



1 For convenient reference and the avoidance of circumlocution, some 

 writers term the stamens which are before the petals epipetalous, those before 

 the sepals episepalous ; but, as this prefix means upon, it is better to restrict 

 these terms to cases of adnation of stamens to these respective parts of the 

 perianth, and to distinguish as 



Antipetulous, those stamens which stand before petals, whether adnate or 

 free, and 



Antisepalous, those which stand before sepals. These terms we find have 

 already been employed in this way by Dr. A. Dickson (in Seemann, Jour. 

 Bot. iv. 275), with the addition of a third, viz. 



Parapetalous, for stamens which stand at each side of a petal, yet not 

 necessarily before a sepal, as in many Rosaceae. 



2 These particular types, with their modifications, are set forth in the 

 characters or distinguishing marks of the orders, tribes, genera, &c. The 

 best generally available illustrations of ordinal types are in Le Maout and 

 Decaisne's Traite' Gene'ral de Botanique, and in Hooker's English edition 

 and revision, entitled A General System of Botany, Descriptive and Analyti- 

 cal, London, 1873. The best morphological presentation is in Eichler's 

 Bliithendiagramme, &c. (Flower Diagrams, Constructed and Illustrated), 

 Leipzig, 1875. 



FIG. 330. Opened flower of Trillium erectum. 331. Diagram of the same. 



