SUPPLEMENT 



and the filaree, Erodium cicutarium, and E. moschatum are 

 equally successful. E. cicutarium is more likely to form pretty leaf 

 rosettes, but E. moschatum, in the vicinity of Los Angeles at least, 

 grows more luxuriantly; the musky, ferny, leaves grow close together, 

 every one erect and rejoicing in the sun, and they form a most 

 exquisite covering for our waste ground and waysides. 



The subject of the arrangement of leaves on the stem, or phyllo- 

 taxy, has been worked out very fully. The spiral arrangement that 

 often exists can be expressed, it has been shown, by a series of frac- 

 tions that progress in the most fascinating way ; but this arrangement 

 can be detected only in vertical shoots that grow under simple condi- 

 tions. Ordinarily on the same plant vertical and horizontal shoots 

 will present different arrangements on account of the twisting of the 

 leaves to accommodate themselves to the light. If a vertical shoot be 

 fastened down to a horizontal position, the leaves will adjust them- 

 selves to the change. Kerner in his "Natural History of Plants," 

 pages 392-424, and Lubbock in "Flowers, Fruits and Leaves," have 

 discussed this subject in a most entertaining way. In NewelPs Reader 

 in Botany, Part I., extracts from both are given. But the details of 

 the subject are much too complex for children ; besides, these obser- 

 vations, made mainly on the trees of England and of Central Germany, 

 assume that the arrangement of leaves is to secure the greatest amount 

 of illumination possible, and this is true of California plants for only 

 a few months in the year. Our trees and perennial summer plants 

 present a notably different appearance from the the trees of countries 

 with a short, moist, warm season. 



But at this season our new leaves have many striking devices for 

 getting as much sunlight as possible. Illustrations are everywhere. 

 It is a good plan to have the children try to sketch leaf rosettes and 

 mosaics, looking down on the plant of course. The leaves of nettle 

 seedlings are arranged on a simple plan and lend themselves well to 

 this exercise. So do climbing plants, for they are obviously most 

 likely of all to form mosaics. 



In the valleys of California, native vegetation seems to be in little 

 danger from cold, and winter plants with hairy or woolly coverings 

 to protect them against sudden changes are not very common. Nor, 

 so far as I have observed, is there a large number of plants that take 

 "sleeping positions " at night. Beside the clovers, the oxalis, wild 

 and cultivated, and the common introduced acacia with bipinnate 

 leaves, are well known examples. The oxalis will take this position 

 when placed in a dark box, and the acacia on being picked or roughly 

 handled, so the folding of these leaves can be observed or drawn at 



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