82 



Elementary Work in Botany. 



the lower side of the pistil and the intnrned edges make a 

 different mark usually depressed along the upper side. 

 Inside, upon the edges of the leaf, grow two or more ovules.* 

 A compound pistil may be formed by several such folded 

 carpels joined with the midribs outside. Such a pistil will 



have as many cells as carpels (Fig. 

 52), and there will usually appear 

 twice as many longitudinal marks, 

 representing, alternately, the mid- 

 ribs and the lines of union. Some- 

 times, as in violets, the carpels are 

 not folded, but joined by their edges 

 to form a single cell, with ovules 

 along the seams on the walls of the 

 ovary (Fig. 610). More rarely the 

 ovules appear on a growth from 

 the center of the base (Fig. 616). Probably this is an out- 

 growth from the leaf edges at their bases. 



Save any flowers you have left and bring more for the 

 next exercise. Secure also many kinds of flower buds. 



EXERCISE 45. 



Arrangement of Floral Leaves in the Bud. Sepals 

 and petals in the bud are usually arranged in one of the 



* We would expect the number to be even as many ovules on one edge as 

 on the other. Though apparently there is but one row of ovules in the carpel of a 

 pea, there are really two, as may be seen by splitting the pod. Stone fruits 

 usually have but one seed ; but there are two ovules. Sometimes there are two 

 or three carpels in a peach blossom, and often the Hungarian prune is double. 



Fig. 61 . Diagrams showing two 

 3-carpelled pistils; one (a) with 

 the ovules on the sides (placentae 

 parietal); the oth^r (b) with 

 ovules on a stem in the center 

 (pacentae central). 



