CHAPTER XVII 
THE SEED PLANTS? 
266. Introductory. In the earlier chapters of this book we 
dealt only with flowering or seed plants, which belong to the 
fourth great division of the plant kingdom. This division is 
known as the spermatophytes, which means “ seed plants.” 
In fact, our earlier discussions considered practically no plants 
except members of the second of the two groups of seed 
plants — the angiosperms, or plants with inclosed seeds. The 
other group of seed plants is the gymnosperms, or plants with 
exposed seeds. Seed plants are the most conspicuous plants 
of the earth, and are the ones which people ordinarily regard 
as composing the plant kingdom. They are most important 
in agriculture, horticulture, landscape and vegetable garden- 
ing, forestry, and the industries... We shall first consider the 
gymnosperms, of which there are over four hundred species, 
some widely distributed and some limited to small areas. 
267. Gymnosperms — the pine as a type. The pine is the 
best general illustration of the gymnosperms and is by far 
the most widely distributed member of the group. Sometimes 
pines form dense forests of tall, straight trees standing close 
together. It is only when thus crowded that they grow tall, 
since, when growing alone in open territory, they secure ample 
light without attaining such a height. 
With a decp-growing central taproot and extensively 
branched lateral roots the pine plant holds its place in the 
1 This chapter summarizes some of the things said about seed plants in 
the first chapters of this book, and adds discussions which will enable the 
student to sce in an elcinentary way the relation of the seed plants to the 
groups of lower plants discussed in the immediately preceding chapters. 
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