File:Students' handbook to accompany Plants and their uses (1914) (14781326855).jpg

Identifier: studentshandbook00sarg (find matches)
Title: Students' handbook to accompany Plants and their uses
Year: 1914 (1910s)
Authors: Sargent, Frederick Leroy, 1863-1928
Subjects: Botany
Publisher: New York : Henry Holt
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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FIG. 55. Rosette of leaves of the common evening primrose, as seen at the end of the first years growth of the plant on the green cells of the leaf. Clearly, therefore, it is usuallyas important for sugar- and starch-making that the leaf shouldcatch all the sunlight it can get, as it is for rapid sailing thata sailboat should expose its sails as fairly as possible to thewind.1 The student will find it well worth while to observethe arrangement of alternate leaves, which are so placed, both 1 Leaves just unfolding from the bud. some of those exposed to tropicalsuns, and certain others (sect. 51) are exceptions. THE STEM AND THE LEAF 73 on vertical and on horizontal branches, that they lie flatwaysto the sun and do not overshadow each other. The way inwhich these results are secured in the case of opposite leavesis well shown in figures 39, 52, and 53. 71. Rosette plants. Some plants, such as the dandelion andthe plantains, have their leaves spread out in the form of a
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FIG. 56. Poison ivy, a root climberReduced rosette at the top of an extremely short stem, which peopleusually suppose to be the crown of the root. Rosette-formersand some other kinds of plants (figs. 54 and 55) are thereforeoften incorrectly said to be stemless. During the first yearof growth from the seed a good many biennials, like the com-mon evening primrose (fig. 55), beets, carrots, and parsnips,form a more or less perfect rosette crowning a stout, fleshyroot. The second year they produce a tall, leafy stem, thenblossom and bear seeds. In rosette plants the leaf is usually 74 INTRODUCTION TO BOTANY narrow at the base and wider at the tip, as in the evening prim-rose, so that nearly all the space between the leaves is tilled in.During which year of the life of a biennial is its principalwork photosynthetic? During which year is it reproductive? Why are beets, carrots, parsnips,and salsify used as food at theend of the tirst seasons growth ? 72. Leaf mosaics. Any combi-nation of l

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