40 LAWS OF FLORAL STRUCTURE 



The important point for the student to note is that while we should 

 thus have three stamens as to form and function, we should have but 

 one as to the numerical plan of the flower, for all have developed from 

 the point belonging to one, and from the elementary tissues of one, and 

 all represent but one leaf-homologue. Sometimes the total number of 

 stamens (or other parts) will thus be multiplied, each element under- 

 going the same change, while at others only one or two in the circle will 

 be thus modified. The latter would result in irregular duplication. In 

 studying the law of position of parts, we must note the great difference 

 between duplication occurring in this way and that from the develop- 

 ment of a new circle independently of any process of chorisis. This 

 peculiarity of position in chorisis is well illustrated by the flower of 

 Tilia (Fig. 34), where three groups or fascicles of stamens can be seen, 

 each produced from one, and in that of Psorospermum (Fig. .38) where 

 there are five, the separation being here confined to the upper portion. 

 In this case, remains of a suppressed circle of stamens are present in the 

 form of gland-like bodies (a). Chorisis is well displayed in the calyx of 

 a floret of the Dandelion (Fig. 41), whose sepals have become divided 

 into numerous bristle-like portions, and in the corolla of the SteUaria 

 (Fig. 39), each of whose petals (Fig. 40) has become divided into two. 



Production by Chorisis of a Part of a Different Kind. — Chorisis some- 

 times produces an organ of a difterent kind from the original, as in the 

 case of the original stamens of the Tilia, where each, besides dividing 

 into about 7 stamens, has at the same time yielded one or more little 

 petals (Fig. 37, a) standing in front of the stamen group. 



Median and Lateral Chorisis. — Chorisis is Median in the case of the 

 last-mentioned petals, which stand in front of the organ out of which 

 they were formed. Lateral in the case of the stamens, which stand 

 beside the organ out of which they were formed. 



An Indefinite Number of Parts. — When the number of organs of one 

 kind, as of petals, as in the rose (Fig. 59), or of stamens (Fig. GO), 

 exceeds twenty, it is commonly spoken of as Indefinite, indicated by 

 the symbol go , although in most cases it falls within certain definite 

 upper and lower limits which are of diagnostic value. 



Indication of the Numerical Plan by Diagram. — The numerical plan 

 and deviations therefrom are often indicated pictorially by diagrams 

 like that shown in Fig. 43. When dots are introduced, as in this dia- 

 gram, they indicate the position of organs which should be present in 

 accordance with the floral type, but which have in that case suffered 

 suppression. A diagram thus marked is called Theoretical, while if 



