106 VEGETABLE ORGANOGRAPHY. 



flower, viz. the sepals, petals, and tepals, where the 

 pieces, free or united at the base, form the calyx, co- 

 rolla, and perigone. Let us first examine the dispo- 

 sition of flowers strictly regular. 



We must first observe whether the parts of an organ 

 are in one row, or if they be in two or more ; when they 

 are strictly verticillate in a single row, there happen four 

 cases : — 



1st. These parts may be disposed in a perfect circle, 

 each of them being fiat or slightly convex ; then they 

 all touch by their margins without overlapping each 

 other, or without being folded inwards : this is called 

 Valvate ^Estivation, because it is analogous to the 

 disposition of the valve of Pericarps, (PI. 19, figs. 2s, 3s, 

 4s, 15p.) The sepals of the Lime-tree and of most 

 Clematideae, the petals of the Vine and of the Arali- 

 aceae, the outer tepals of Tradescantia, and the leaflets 

 of the involucra of Othonna Cheirifolia, present examples. 

 The pieces of integuments with valvate aestivation are 

 usually remarkable on account of their margins being 

 thick, indurated, sometimes slightly glutinous or velvety 

 in their infancy ; circumstances which contribute towards 

 retaining them in this position. 



2d. These same parts may be disposed in a perfect 

 circle, but each with its margin folded inwards ; they 

 appear valvate externally, but when we open the bud, 

 we see the fold of each piece. This constitutes In- 

 duplicate Estivation (PI. 19, fig. 6) ; it has 

 much affinity with the preceding, as it is sometimes 

 found in plants very near, as regards their form, to 

 those with valvate aestivation, such as Clematis Viti- 

 cella: the portion folded inwards is usually thin and 

 membranous. 



3d. We may, from analogy, admit a Reduplicate 

 ^Estivation, which takes place when the pieces are 





