CONIFERALES 273 



The origin of the root will be considered under the heading 

 "Embryogeny." 



The hypocotyl. — In the young seedling the hypocotyl is the most 

 prominent and most extensive part of the plant. In its lower part 

 the structure is much like that of the root, with phloem groups al- 



FiG. 279. — Finns laricio: transverse section of hypocotyl, showing four protoxylem 

 points, with four alternating groups of phloem. There are also two resin ducts, not well 

 differentiated at this stage. Two stomata are shown in the epidermis; X 160. 



ternating with the exarch bundles in typical radial arrangement 

 (fig. 279). But there is no scaling off at the outside, and stomata are 

 present, although not so abundant as in the leaves and young stem. 

 Higher up in the hypocotyl the bundles begin to rotate, making a 

 half-turn, so that near the cotyledons a transverse section shows an 



