LESSON 31.] THE COMMON FLAX. 187 



LESSON XXXI. 



HOW TO STUDY PLANTS : FURTHER ILLUSTRATIONS. 



541. BEGINNERS should not be discouraged by the slow progress 

 they will necessarily make in the first trials. By perseverance 

 the various difficulties will soon be overcome, and each successful 

 analysis will facilitate the next. Not only will a second species of 

 the same genus be known at a glance, but commonly a second genus 

 of the same order will be recognized as a relative at sight, by the 

 family likeness. Or if the family likeness is not detected at the first 

 view, it will be seen as the characters of the plant are studied out. 



542. We will help the student along the way by one or two more 

 examples. We will take in the first place the common cultivated 

 Flax, which will serve our present purpose, although not truly a 

 wild plant in this country. Turning, as before, to the Artificial Key, 

 on p. xvii of the Introduction to the Manual, the student asks first, 

 Is the plant PH^ENOGAMOUS or FLOWERING? Of 



course it is ; the blossom, with its stamens and pistils, 

 answers that question. Next, To which of the two 

 classes does it belong? If we judge by the stem, we 

 ask whether it is exogenous or endogenous (422-424). 

 A section of the stem, considerably magnified, given on 

 page 151 we may here repeat (Fig. 362) ; it plainly 

 shows a ring of wood between a central pith and a bark. It is 

 therefore exogenous. Moreover, the leaves are netted-veined, though 

 the veins are not conspicuous. If we judge from the embryo, there 

 will be little difficulty in dissecting a flax-seed, and in finding that 

 almost the whole interior is occupied by an embryo with two cotyle- 

 dons, much like that of an apple-seed (Fig. 11, 12) ; so it is dico- 

 tyledonous. If we turn to the parts of the blossom, we perceive 

 they are five throughout (Fig. 363, 365), a number which occurs 

 in the first class only. All these marks, or any of them which the 

 student is able readily to verify, show that the plant belongs to 

 Class I. DICOTYLEDONOUS or EXOGENOUS PLANTS. 



543. To which subclass, is the next inquiry. The ovary in the 



FIG. 362. Section of the stem of Flax, magnified. 



