132 THE LIVING CYCADS 



matter of fact the cycad, under favorable conditions, 

 has^no resting period, development being continuous 

 from fertilization to old age and death, with only such 

 temporary dormancy as may result from exhaustion 

 after the cone-bearing stage has been reached. 



As the embryo within the germinating seed elongates, 

 the hard coleorhiza presses against the stony layer of 

 the seed coat with such force that an irregular fracture 

 is produced, through which the basal part of the embryo 

 protrudes more and more. As soon as the coleorhiza 

 gets through the fracture, the tip of the root partly 

 digests and partly tears its way through the coleorhiza 

 and then begins to turn down into the soil. 



Practically all cycad seeds are longer than broad, and 

 consequently the long axis of the embryo lies nearly 

 parallel with the surface of the ground. In nature most 

 of the seeds germinate on the surface of the soil, so that 

 it is easy to observe the appearance of the fracture, the 

 emerging coleorhiza, and the young root (Figs. 71-73). 



The young seedling continues to back out until the 

 coleorhiza, the root, the cotyledonary tube, and a small 

 portion of the cotyledons are outside the seed coats, but 

 the principal part of the cotyledons remains inside the 

 seed, absorbing the endosperm and passing it on to the 

 growing seedling. After all the endosperm has been 

 used, the nutritive material within the cotyledons them- 

 selves is absorbed, and they wither away. The stony 

 seed coat and the withered cotyledons inside it may 

 cling to the seedling for a year or two. 



Usually the emerging seedhng shows only one leaf, 

 the next leaf not appearing for a month or more. Leaves 

 continue to appear, one at a time, for a few years, the 



