122 THE GYMNOSPERMS 



bald cypress and larch are deciduous, i.e., shed their entire 

 foliage each year and are bare during the winter season. 



A cross-section of the stem will show the annular rings and 

 medullary rays the same as in dicotyledonous plants. Very thin 

 sections should be made and mounted in water for study under 

 the microscope. Each section is cut at right angles to the other 

 two as follows : 



(a) The cross-section which will show the varying thick- 

 nesses of the cell-walls by which the annular rings are produced, 

 the large thin-walled cells of the late summer growth. It will 

 also show the medullary rays and large resin ducts. (&) The 

 radial section which is cut longitudinally and on a plane passing 

 through the axis of the tree {i.e., quarter sawed) will show the 

 peculiar markings of the cells (tracheids). By studying care- 

 fully made tangential sections which are also longitudinal but 

 at right angles to the radial section we can get some idea of these 

 peculiar markings. 



The cones are of two kinds, staminate and pistillate. They 

 correspond to bunches of staminate and pistillate flowers. We 

 are most familiar with the pistillate (or carpellate) (Fig, 82, c) 

 cones and will give them first consideration. They become the 

 mature cones which we find hanging on the trees. These cones 

 are made up of scales, corresponding to needles or leaves, but 

 instead of being arranged in circles as in the case of a true 

 flower, they are arranged in spirals. You will also note that 

 when they spread apart they each bear two mnged seeds. 



But let us examine an immature cone such as we will find 

 early in the spring. (Fig. 82, c.) Each cone is small and the 

 scales naturally spread so as to expose two ovules (macrosporan- 

 gia) . (Fig. 82, d. ) This is quite different from the true flower- 

 ing plants in which the ovules are always enclosed in an ovary. 



Pollination.— Tn the spring we will also find clusters of 

 very small staminate cones. (Fie;. 82, a.) Each scale of these 



