[33] As subclass in Engler and Prantl.
[34] As class Filicales in Engler and Prantl.
[35] As class Equisetales in Engler and Prantl.
[36] As class Lycopodiales in Engler and Prantl.
[37] Suggestions to the teacher.—In the study of the flowering plants in the secondary school and in elementary courses three general topics are suggested. 1st, the study of the form and members of the plant and their arrangement, as in Chapters XXXVIII-XLV. 2d, the study of a few plants representative of the more important families, in order that the members of the plant, as studied under the first topic, may be seen in correlation with the plant as a whole in a number of different types. 3d, the study of plants in their relation to environment, as in [Chapter XLVI]. The first and second topics can be conducted consecutively in the classroom and laboratory. The third topic can be studied at opportune times during the progress of topics 1 and 2. For example, while studying topic 1 excursions can be made to study winter conditions of buds, shoots, etc., if in winter period, or the relations of leaves, etc., to environment, if in the growing period. While studying topic 2 excursions can be made to study flower relations, and also vegetation relations to environment (see Chapters XLVI-LVII of the author’s “College Text-book of Botany”). It is believed that a study of these three general topics is of much more value to the beginning student than the ordinary plant analysis and determination of species.
[38] It is interesting to note that in some foliage shoots the stem is entirely subterranean. See discussion of the bracken fern and sensitive fern in [Chapter XXXIX].
[39] Some fibers occur also very frequently in the Fundamental System, forming bundle-sheaths, or strands of mechanical tissue in the cortex.
[40] Besides these specialized shoots for the storage of food, food substances are stored in ordinary shoots. For example, in the trunks of many trees starch is stored. With the approach of cold weather the starch is converted into oil, in the spring it is converted into starch again, and later as the buds begin to grow the starch is converted into glucose to be used for food. In many other trees, on the other hand, the starch changes to sugar on the approach of winter.
[41] This topic was prepared by Dr. K. M. Wiegand.
[42] See discussion of Tropophytes in [Chapter XLVI].