SUPERPOSITION OF SUCCESSIVE PABTS. 



197 



which they are the types, afford familiar cases of a single circle 



of stamens placed before the petals. In Vitis, there are green 



nectariferous lobes or processes from 



the receptacle, alternate with and inside 



the stamens : there is no good reason to 



suppose that they answer to a second 



row of stamens. All isostemonous Por- 



tulacacese have the stamens before the 



petals ; and, when the stamens are fewer 



than the petals, those which exist occupy 



this position. Among the orders with 



gamopetalous corolla, such anteposition 



is universal in Plumbaginacese, Primu- 



laceae, the related Myrsinacese, and in 



most Sapotacese, in the latter usually 



with some complications. 



363. The earliest and the most obvious explanation of the 

 anomaly is that of the suppression of an outer circle of stamens, 

 and to this view recent morphologists are returning. 1 Observa- 

 tion supplies no vestige of proof of it in Rhamnaceae and Vitaceae ; 

 but, in the group of related orders to which the Primulaceae be- 

 long, evidence is not wanting. For Samolus and Steironema 

 both exhibit a series of rudimentary organs exactly in the place 

 of the wanting circle of stamens, which may well be sterile fila- 

 ments. In the allied order Sapotaceae, while Chrysophyllum 

 has in these respects just the structure of Primulaceae, and 

 Sideroxylon that of Samolus, Isonandra Gutta (the Gutta-percha 

 plant) has a circle of well-formed stamens in place of the sterile 

 rudiments of the preceding ; that is, alternate with the petals, 



1 Eichler, Bliithendiagramme, passim, and in preface to Part II. xviii., 

 relating chiefly to obdiplostemony. The principal opposing view is that of 

 St. Hilaire, Duchartre, &c., maintaining that corolla and stamens here repre- 

 sent one circle of organs doubled by median chorisis ; upon which see note 

 under a following paragraph. According to that hypothesis, there is no 

 androecial circle in such blossoms, or only vestiges of one, but the petals have 

 supplied the deficiency by a supernumerary production of their own ! The 

 more plausible hypothesis of Braun, that of a suppressed interior circle 

 of extra petals, would restore the alternation, and make the extant sta- 

 mens the fourth floral circle, as does the adopted explanation. Braun's 

 hypothesis, if it insists that an extra row of petals is wanting, supposes the 

 suppression of that which very rarely exists ; but, if of stamens, then the 

 supposed suppression is of that which is so generally present, or with indi- 

 cations of presence, as properly to be accounted a part of the floral type. 



FIG. 379. Flower of the Grape Vine, casting its petals before expansion. 380. The 

 same, without the petals: both show the glands of the disk distinctly, within the 

 stamens. 381. Diagram of the flower. 



