CALIFORNIA PLANTS IN THEIR HOMES 



CHAPTER XIV. 



PLANT FAniLIES. PART II. EXOGENS, OR 

 DICOTYLEDONS. 



How many seedlings can you recall with two seed- 

 leaves or cotyledons? Aid your memories by turning to 

 Figs. 5, 6 and 8 in Chapter II. These, and like plants, are 

 called dicotyledons. Find some of them older grown, and 

 cut across their stems to see how their woody strands are 

 placed. Plants with this arrangement of wood in the stem, 

 which is the best possible, are called exogens. How are 

 the strands, or veins, arranged in the leaves? Compare the 

 leaf of the castor bean with that of the corn, for instance. 

 Which do you think the stronger? Which group, endo- 

 gens or exogens, has the greater variety in form of leaves ? 

 Do you remember why some plants are better off because of 

 their slashed or divided leaves? Because exogens, or 

 dicotyledons, as a class, are better able to meet dangers 

 than endogens or monocotyledons, they are considered of 

 higher rank, but it does not follow that they are more use- 

 ful to man. 



Many botanists put in the lowest group of dicotyledons 

 those that have small, incomplete, and, usually, crowded 

 flowers. The willow, walnut, sycamore, alder, oak and fig 

 belong here; so do some other useful trees, which, perhaps, 

 you do not know; other nut-bearing trees, such as the 

 chestnut, pecan and beech, and shade and timber trees, like 

 the elm and birch. There is the mulberry, which feeds 



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