38 LAWS OF FLORAL STRUCTURE 



one stamen, and one carpel, and is, in its present state, Monomerous 

 or One-merous. The symmetrica] flower of Bicuculla (Fig. 27) possesses 

 two sepals (a), four petals (6 and b'), six stamens (c), and a two-carpelled 

 pistil {d and e), and is Dimerous or Two-merous. That of the Veratrnm 

 (Fig. 28) is similarly based on the plan of three, and is Trimerous or 

 Three-merous. Oenothera (Fig. 29) is Tetramerous or Four-merous, 

 and Geranium (Fig. 30) is Pentamerous or Five-merous. Fig. 43 displays 

 the plan of such a flower in cross-section and admirably illustrates our 

 second law also. 



Suppression and Duplicatio7i. — Suppression results in the posses- 

 sion of less parts of one kind than are possessed by the typical flower, 

 while Duplication results in the possession of more. From what follows 

 it will be seen that neither suppression nor duplication necessarily inter- 

 feres with the numerical plan, although they frequently do so. 



In the monochlamydeous flower of Pulsatilla (Fig. 16) suppression 

 of the entire circle of petals has occurred, although vestiges of them 

 remain. In the staminate and pistillate flowers of the willow, all 

 organs except a single series are suppressed. In the Claytonia (Fig. 45) 

 one complete stamen-circle has been suppressed. 



In all these cases the remaining parts accord with the numerical plan 

 and the flowers are still symmetrical. Suppression which thus results 

 is called Regular Suppression. 



Irregular Suppression. — This is displayed in the calyx of Claytonia, 

 with three of its five sepals wanting, in the androecium of the 4- or 

 5-merous flower of Horse-chestnut, which usually wants 1 to 3 of the 

 requisite number of stamens, and in the gynaecium of the 4-merous 

 flower of the olive (Figs. 31 and 32), which has but two carpels remaining. 

 In this flower, both forms of suppression appear to have occurred, for 

 but 2 of its 8 original stamens remain. To irregular suppression the 

 term Abortion has been applied, while by others this is restricted to 

 suppression in which a vestige of the lost organ remains, as in case of the 

 petals of Pidsatilla, and one set of stamens in Fig. 38, a. 



Regular Duplication. — Duplication, like suppression, presents a 

 regular and an irregular form. Kegular duplication is seen in the 

 5-merous flower of the strawberry (Fig. 36), with its 10 sepals; the 

 3-merous flowers of Magnolia (Fig. 35), with 6 to 9 petals, and Meni- 

 spermum, with 12 to 24 stamens, and in the 5-merous flower of Maha, 

 which frequently has 10 carpels. 



Chorisis and Syngenesis. — The development into two or more sepa- 

 rate parts of an organ originally entire is called Chorisis. This is exhibited 



