Ol HaCCHAKIS GENISTELLOIUES OI>0 



On the third the main shoot withered ; and one of the buds 

 produced a branch on which the win^s are apparently normal, 

 but on which three small leaves have been found. Four other 

 plants produced leaves on branches that retained their wings. 



The apogeotropic habit of the secondary branches made anotlicr 

 experiment possible. A plant on which the main branch had fallen 

 from its own weight and on which there were a number of such 

 upright shoots was layered — that is, had its main s«:em covered 

 with earth. After allowing the branches to rest in this condition 

 for .some time, the connection of the vertical shoots with one 

 another and with the main stem was severed. However, although 

 all the shoots flourished and grew into separate plants, none pro- 

 duced the leaves. 



To sum up briefly the mo.st important points brought out in 

 this investigation : 



J. Baccharis genistelloidcsx'^ 2l plant remarkably well adapted 

 by the loss of leaves, by the po.sition of the wings, and by the 

 coverings of the cutin, wax and hairs, to withstand a high degree 

 of both dryness and insolation. 



2. The glandular hairs differ from the hairs previously de- 

 .scribed in the Compositae in the possession of chlorophyl, and the 

 whip-hairs in being biserial. 



3. The early acquisition of lignin in the bast of the stem, and 

 of mechanical tissue in the wings, gives to the plant its character- 

 istic rigidity, and at the same time necessitates a short period of 

 elongation. 



4. The leaves found in any given portion of the stem on the 

 older parts of the plant resemble closely the leaves of other species 

 of Baccliaris. 



5. The leaf differs from the wing in structure in showing 

 marked dorsiventrality, which is absent in the latter. 



6. While the wings are directly continuous with the margins of 

 the scales and of the leaves when present, and while they follow 

 the phyllotaxy, they are to be considered morphologically as 

 lateral-vertical expansions of the stem and not as " decurren 

 leaves." 



7. The shoots have been shown to be markedly apogeotropic 

 and positively phototropic. 



