Laboratory Exercises in Botany (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: EXERCISE II. STUDY OF STEMS. Some or all of the following stems may be studied: Twigs of Hickory (Carya alba, Nutt.), Horse-chestnut (Esculus Hippo- castanum, L.), Balsam Poplar (Populus balsamifera, L.), Ash (Fraxinus Americana, L.), Lilac (Syringa vulgaris, L.), Maple (Acer dasycarpum, Ehrh.), Basswood (Tilia Americana, L.), the climbing stems of Green Briar (Smilax rotundifolia, L.), and the herbaceous stems of Sunflower (Helianthus annnus, L.), and Maize (Zea Mays, L.). Let there first be examined carefully a twig of the common Shellbark Hickory, and the study of this will form a basis for the study of the rest. Any well-developed twig of the tree, representing a growth of at least two years and gathered late in antumn or in early spring before the leaves unfold, will serve the purpose. I. The External Characteristics.?Parts and Marking.?(1) At the apex or upper end of the twig is observed a large scaly bud called the terminal bud. Below this, at intervals along the stem, are other buds, smaller in size, but otherwise similar. These buds, since they occur just above where the leaf of the previous season joined the stem, are called axillary buds. The heart-shaped scar cansed by the fall of the leaf may be seen immediately below the bud in each case. These buds and leaf- scars, it should be observed, are not arranged without order, but in a regular spiral about the stem. If the twig has had a rapid growth, we are liable to find more than one bud, sometimes as many as three, in or near the leaf- axil. In the Hickory these buds are arranged one above the other, the smallest nearest the leaf-scar, the next larger just above this, and the largest most remote from the scar. The real axillary bud is the first mentioned and smallest; the others are called supernumerary b...