184 



HOW TO STUDY PLANTS. 



[lesson 30. 



little higher np on the receptacle, an indefinite number of stamens ; 

 and, lastly, covering the summit or centre of the receptacle, an in- 

 definite number of pistils. 

 A good view of the whole 

 is to be had by cutting the 

 Ti Wb) lllif'/i^lnilllM Itll Jll flower directly through the 



middle, from top to bottom 

 (Fig. 358). If this be done 

 with a sharp knife, some of the pistils will be neatly divided, or may 

 be so by a second slicing. Each pistil, we see, is a closed ovary, 

 containing a single ovule (Fig. 359) ascending from near the base 

 of the cell, and is tipped with a very short broad style, which has 

 the stigma running down the whole length of its inner edge. The 

 ovary is little changed as it ripens into the sort of fruit termed an 

 akene (Fig. 360) ; the ovule becoming the seed and fitting the cell 

 (Fig. 361). Reverting to the key, on p. 13, we find that the class 

 to which our plant belongs has two subclasses, one " with" pistil of 

 the ordinary sort, the ovules in a closed ovary "; the other " without 

 proper pistil, the ovules naked on a scale," &c.- The latter is 

 nearly restricted to the Pine Family. The examination already had 

 makes it quite clear that our plaht belongs to the first subclass, 

 Angiospekmous Exogenous or Dicotyledonous Plants. 



530. We have here no less than 110 orders under this subclass. 

 To aid the unpractised student in finding his way among them, they 

 are ranked under three artificial divisions; the Polypetalom, the 

 Munopetalous, and the Apetalous. The plant in hand being fur- 

 nished, in the words of the key, " with both calyx and corolla, the 

 latter of wholly separate petals," is to be sought under I. Poly- 

 PETALO0S Division; for the analysis of which, see p. 14. 



531. Fully half the families of the class rank under this division. 

 The first step in the key is to the sections A and B ; to the first of 

 which, having "stamens more thhn 10, and more than twice the 

 number of the sepals or divisions of the calyx," our plant must pertain. 



532. Under this we proceed by a series of successive steps, their 

 gradations marked by their position on the page, leading down to 

 the name of the order or family, to which is appended the number 



FIG. 3B9. A pistil taken from a Buttercup (Rannncnlns bulbosus), and more magnifled ; 

 its ovary cut tlirougli lengthwise, showing the oTulc. 360. One of its pistils when ripened 

 into a fruit {achtnium or akene). 361. The same, cut through, to show the seed in it. 



