306 PLANTS 



carpels of gymnosperms grow in groups, called cones. 

 These open when the seed is ripe, and allow it to 

 escape. Gymnosperms are also called conifers, that is, 

 "cone bearers." The cones that produce the seeds are 

 "pistillate" cones. Fertilization is carried out by pollen 

 produced in other cones called "staminate" cones. 



The leaves of the common gymnosperms are not shed at the coming 

 of winter. After the new leaves have made their growth, the old ones 

 fall; but the tree is never without leaves. The leaves are usually 

 needle-shaped. In some cases, as in the ' ' Norway " pine, there are two 

 leaves in a whorl; in the "white" pine there are five. 



The wood of the evergreens is "soft" wood. It is valued beca'use 

 it is durable, even in the "weather," and because it is easily worked. 

 The wood of the white pine is especially prized. 



The most common seed plants, those we have studied 

 in 307 to 320, do not have the seed "naked," but "in 

 a closed vessel." For this reason they are called angio- 

 sperms (pronounced an'-ji-o-sperms). The "closed ves- 

 sel" is the carpel. The most highly developed of the 

 angiosperms, such as the dandelion, daisy, aster, and 

 sunflower, have composite flowers. In these plants a 

 large number of individual flowers have "clubbed to- 

 gether," and grow upon a single stalk. The center of 

 the composite "flower" is called the disk. It contains 

 the disk-flowers a multitude of them each with a 

 closed corolla and a full set of reproductive organs. 

 Sometimes there are sepals, too. The next outer struc- 

 ture, which looks like a whorl of petals, is really a circle 

 of flowers ray-flowers with the corollas split open, 

 so that each looks like a strap. Outside of all are scales, 

 which look like sepals. 



