CHORISIS OR DEDUPLICATION. 



203 



such sessile palmately compound leaves as those of some species 

 of Aspalathus. It is incomplete when division does not extend 

 to the base; as in Fig. 387, 393. Compare, as a 

 proximate homologue of this, a petal of Mignonette, 

 Fig. 385. But proper chorisis requires that the 

 supernumerar} T organs should be developed like 

 unto the original organ which is thus multiplied, or 

 should complete their sj-mmttry, whatever it be. 



374. St. Hilaire distinguished two kinds of deduplication ; viz., 

 collateral when the members stand side b}' side, and parallel 

 when an organ becomes double or multiple antero-posteriorly. 

 The latter, sometimes called vertical, and sometimes transverse, 

 is better named median chorisis. The collateral is the origi- 

 nal and typical chorisis. Most botanists incline to restrict the 

 name to this, and to give some other explanation and name to 

 the median form of augmentation. But some cases, such as 

 those of Tilia and Sparmannia, are clearly of the same nature 

 as the collateral, and may be a disguised form of it ; there are 

 others which may be explained in accordance with it ; and there 

 are such transitions between some of these and coronal out- 

 growths that the term chorisis is most conveniently made to 

 comprise augmentation or doubling in either plane. Distinct 

 anteposition, however, may be explained in other wa}*s. (357.) 



375. Typical or Collateral Chorisis, in which the members, 

 together answering to one leaf, normally stand side by side, 

 occurs in many families of plants, and 



in a variet}' of forms. A few are here 

 presented. 



376. Elodes Virginica (a common 

 marsh plant of the Hypericum family) , 

 like most of its near relatives, has its 

 calyx and corolla on the plan of five, 

 its stamens and carpels on the plan of 



three, as is shown in the diagram, Fig. 386. This makes a break 

 in the s^ymmetry between the corolla and the stamens ; but all 

 within is in regular alternation when the three stamens of each 

 cluster are counted as one as their union at base into a ph<danx 

 (Fig. 387) may suggest. These phalanges alternate with the 

 three carpels, and therefore stand where single stamens belong. 

 The three conspicuous green projections, which in a general way 



FIG. 385. A petal of Mignonette (Reseda odorata), with many parted blade, 

 enlarged. 



FIG. 386. Diagram of flower of Elodes Virginica, with three phalanges of stamens 

 forming the inner circle, and three glands answering to the outer circle. 387. A de- 

 tached phalanx of three stamen^. 



