Teachers' Leaflet. 



549 



Observations by pupils: 



1. Can you tell by its appearance to what great plant-family the 

 dahlia belongs ? 



2. Do you know any common flower which has ray florets and a 

 central disc like the single dahlia? 



3. Compare the leaf with that of the beggar-tick or pitchfork weed. 

 Should you not guess from their appearance that they are near relatives? 

 In what are they alike, and how do they differ? 



4. Do the leaves of the dahlia grow on opposite sides of the stalk or 

 alternately? Are they simple leaves or compound? Do you observe 

 anything remarkable in the way the leaves are attached to the stem? 



5. Study the tuber. Has it " eyes " from which shoots may grow ? 

 Is it an underground stem like the potato? If it has no eyes and is 

 severed from its crown, do you think it can grow? 



Facts for the tcacher.—Sho-w the children by direct observation — by use of a 

 lens, if it can be done, — that some flowers that appear to be only one, are really 

 whole collections of blossoms living on one stem; and the dahlia belongs to this, 

 the "Composite"' family. The fact can be brought out best by a "single" fiowrer. 

 The dahlia is so close a relative of the Bidens or 

 beggar's tick, that in some species the leaf forms 

 seem almost identical. 



The leaves are opposite and at the place of 

 attachment to the stalk the petioles are much 

 dilated so that they unite, forming a complete 

 ring about the main stem, and when fallen they 

 leave a ring-like scar. They are compound 

 leaves and are remarkable in the fact that the 

 leaflets also are often compound but not always ; 

 a single leaf may have both simple and compound 

 leaflets. Observe the groove 

 on the upper side of the 

 midrib, down which the rain 

 and dew is carried to the 

 roots of the thirsty plant. 

 The root is a crown tuber 

 and does not put forth side 

 buds like the potato. 

 "Toes" without crowns can- 

 not form new plants. 



LESSON XXII. 

 VARIETIES OF DAHLIAS. 



Purpose. — To show 

 how greatly the forms 

 of plants may be 

 changed by careful 

 choice and cultivation. ^ f^n ^^„^;^ dahlia. 



