54 



BOTANY 



Examine a capsule of Jimson weed. Cut a cross section and decide 

 how many locules there are. Where is the placenta? How many do you 

 find? Open a green fruit to see the number of seeds produced. Draw the 



cross section to show the attach' 

 ment of the seeds. Show also the 

 method of dehiscence (splitting of 

 capsule) . How does the fruit pro- 

 vide for scattering the seeds ? 



SiLiQUE. — Attention is called 

 to the two or three odd types of 

 capsule frequently seen. All flow- 

 ers belonging to the mustard family 

 form a silique. This differs from a 

 legume in the presence of a false 

 partition which divides the interior 

 into two parts. Another common 

 form is the purse-shaped capsule; 

 it is known as silicle, best seen in 

 the fruit of the peppergrass or of 

 the shepherd's purse. 



Capsules ; each is made up of five carpels. 



Indehiscent Fruits. — Among those of most importance to man 

 economically are the dry indehiscent fruits. Such fruits do not 

 open to allow the escape of seeds. Among them are found the 

 grainS; such as wheat, oats, and corn. Many of our most destruc- 

 tive weeds bear indehiscent dry fruits. 



AcHENE. — The simplest and commonest of all indehiscent fruits is the 

 achene. This we have seen before in the buttercup and on the outside of 

 the strawberry. In many flowers, 

 especially those of the great com- 

 posite family (a group of plants 

 containing many of the most nox- 

 ious weeds, as the thistle, dande- 

 lion, sneezeweed, and others), 

 hairlike projections are developed 

 from the upper part of the fruit. 



These projections (collectively called the pappus) are of use 



to the fruit because they aid in carrying it to other localities 



at some distance from the parent plant. 



Nut. — A nut can usually be recognized by the hard 



pericarp, or ovary wall, which fits tightly over the kernel. 

 Cross section of '^^^ latter, with its covering, is the true seed. The acorn 

 a pecan nut. and pecan are good examples of nuts. The Brazil nut is 



The acorn, a nut in which the involucre only 

 partly covers the fruit. 



