144 LABOllATOBY STUDIES OF THE FRUIT 



XIII. LABORATORY STUDIES OP THE FRUIT 



The whole purpose of the fruit is embodied in the seed. 

 The portion external to the seed is important in the life 

 history of the plant only as it ministers to the maturing, 

 preservation, transporting, or planting of the germ. The 

 ways in which the character of the exterior parts of the 

 fruit affects the destiny of the seed will be studied after 

 the general structure of fruits has been examined. 



The studies of the first Exercise have to do with the 

 parts of the fruit external to the seed ; the second 

 Exercise is concerned with the seed itself ; and the third, 

 with dissemination. 



Exercise XXXV. Floral Organs Involved in the Fruit 



Wild Indigo. — Xotice the base and the slender termination of the 

 pod. What was this termination in the flower ? What still surrounds 

 the pod stalk? Can you discover any marks of other organs, now 

 fallen away ? Open the pod : where are the seeds attached ? Pod and 

 seeds are the ripened forms of what members of the flower? How 

 many carpels in this fruit ? The ripened ovary is termed the pericarp. 



Violet. — After examining all exterior features, cut a cross section. 

 With the lens, and by trying the seeds wdth a needle, find the places 

 of attachment. How many placentce f Of how many carpels is the 

 pod composed? From dried and opened specimens determine whether 

 the pod bursts between the carpels or along the carpellary midribs. 

 Of what floral organ does the fruit consist ? 



Cranberry. — Opposite the stem end is a slight hollow, roughly 

 square, edged and often nearly covered in by four projections. Cut 

 these projections away. Observe the bottom of the depression. At 

 the center is a single scar, marking the position of what member of 

 the flower ? Around this, within the crater, notice two circles of scars. 

 What are they ? Finally, what is the nature of the four projections 

 first noticed and then cut away? Parts of what organs of the original 

 flower now compose the berry ? 



Cut the fruit transversely. How many carpels compose it? The 

 size of the cavities in which the seeds lie is striking when compared 

 wdth the minute size of the seeds themselves. Will the berry float ? 

 Try it. Count and record the number of seeds. 



Draw : Wild Indigo. The pod, with persistent calyx. This sort of 

 fruit is termed a legume. 



Violet. Cross section, to show the seeds attached ( x 5). The 

 dehiscent fruit ( X 2). The fruit is termed a capsule. 



