Page:First course in biology (IA firstcourseinbio00bailrich).pdf/91

 CHAPTER X

THE STEM—ITS GENERAL STRUCTURE

There are two main types of stem structure in flowering plants, the differences being based on the arrangement of bundles or strands of tissue. These types are endogenous and exogenous (page 20). It will require patient laboratory work to understand what these types and structures are.

Endogenous, or Monocotyledonous Stems.—Examples of endogenous stems are all the grasses, cane-brake, sugar-*cane, smilax or green-brier, palms, banana, canna, bamboo, lilies, yucca, asparagus, all the cereal grains. For our study, a cornstalk may be used as a type.

, showing the scattered fibro-vascular bundles. Slightly enlarged.

A piece of cornstalk, either green or dead, should be in the hand of each pupil while studying this lesson. Fig. 69 will also be of use. Is there a swelling at the nodes? Which part of the internode comes nearest to being perfectly round? There is a grooved channel running along one side of the internode: how is it placed with reference to the leaf? with reference to the groove in the internode below it? What do you find in each groove at its lower end? (In a dried stalk only traces of this are usually seen.) Does any bud on a cornstalk besides the one at