THE NATURE OF FRUITS 



331 



thus may have more than one seed chamber. (See Figure 

 145, B.) The parts into which the walls of pods and cap- 

 sules separate are called valves; pods have two valves, while 

 capsules have as many valves as there are carpels. In 

 some cases the valves separate suddenly, twisting as they 

 separate, aijd so throw the seeds out with some violence. 

 (See Figure 145, A.) Such fruits are said to be explosive. 

 The fruit of touch-me-not is a familiar example. The cap- 

 sules of evening prim- 

 rose, morning-glory, 

 and larkspur are ex- 

 amples of those which 

 remain on the plant 

 for a long time after 

 they dehisce ; they 

 allow the seeds to fall 

 out gradually or to be 

 scattered by the wind. 

 (See Figure 145, B.) 

 Pods are especially 

 characteristic of the 

 pea family (Legumi- 

 nosa) and of the mustard family (Cruciferce.) Sometimes 

 dehiscent fruits open by pores, as in the poppy. 



Indehiscent fruits are more common than the dehiscent 

 ones. Akenes and grains are examples. (See page 327.) 

 Berries, stone fruits (drupes), acorns, nuts, pomes, and 

 samaras are other examples of indehiscent fruits. In such 

 fruits the seed escapes by the gradual decay of the tissue 

 around it, or the sprouting embryo grows out through the 

 wall of the old fruit. Samaras are the familiar winged 

 fruits of many kinds of trees. (See Figure 146.) Pomes 



Fig. 145. 



I B 



— A , pod of the lupine, one of the pea 

 family ; the valves have twisted as they sepa- 

 rated, thus scattering the seeds. B, capsule of 

 the evening primrose; the four valves begin to 

 split at the apex. 



