38 



PISTILS AND STAMENS 



mature pod is threshed, only one seed is found. In Alfalfa only 

 about one third of the ovules produce seed. In the Apple, Pear, 

 Tomato, and other fruits some of the ovules often fail to develop, 

 and in case of seedless fruits none of the ovules complete their 

 development. In most fruits the production of seed is not an 

 important feature to the plant grower, the seedless fruit in many 

 cases being more desirable; but in case of Clover, Alfalfa, Flax, 

 and other plants valuable for seed, the value of the plant as a seed 

 producer is directly related to the number of ovules which be- 



FIG. 44. Surface view of an ovule 

 at two stages of development. A, 

 stage of development showing the 

 integuments (a, &) growing up over 

 the nucellus (n). B, older stage in 

 which the integuments have closed 

 over the nucellus, leaving only a 

 small opening, the micropyle (m). s, 

 the funiculus. Much enlarged. 



FIG. 45. Section' through 

 the ovule of Red Clover show- 

 ing the embryo sac. em, em- 

 bryo sac with the egg (e) and 

 the primary endosperm nucleus 

 (en) indicated; i, integuments; 

 ra, micropyle. Many times 

 enlarged. 



come seed. How much could the seed yield of Clover and Alfalfa 

 be increased if they could be made to develop all of their ovules 

 into seed? If clover seed were selling at $10 per bushel, what 

 would be the value of the increased yield on ten acres of average 

 Clover? 



Parts of the Ovule. The ovule consists of a main body and 

 a stalk known as the funiculus which connects to the ovary wall. 

 The main body consists of a central (usually rounded) portion 

 called nucellus, which is enclosed by one or more coverings called 

 integuments that grow up from the funiculus. In Figure 40, 

 showing the ovules of Clover, the stalk or funiculus is at st; the 

 central portion or nucellus of the main body is at r&; the coverings 

 or integuments of the nucellus are at i. Turn to this Figure and 

 point out these parts. In the ovule of the Corn, shown in Figure 

 41, the funiculus is apparently absent. In Figure 44 is shown a 



