184 



HOW TO STUDT PLANT& 



[lesson 30. 



little higher up 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 

 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 ovaiy, 

 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). Eeverting 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 plant belongs to the first subclass, 

 Angiospermous Exogenous or Dicotyledonous Plants. 



630. 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 Polypetahus, the 

 Munopetalous, and the Apetahus. 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. Polt- 

 PETALOUS 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 than 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. 369. A pistil taken ftom a Buttercup (Ranunculus bulbosus), and more magnified ; 

 its oTary cut through lengthwise, showing the ovule. 360. One of its pistils when ripened 

 Into a fruit ifickenium or alcene). 861. The same, cut through, to show the seed in It. 



