44 



STEMS. 



[section 6. 



sort, likp lliose of tlie Solomon's Seal (Fig. 99), which gave lliis name to 

 the plant, from their looking somewhat like tlie impression of a seal upon 



wax. Here the 

 rootstock sends up 

 every spring an 

 herbaceous stalk or 

 stem, which bears 

 the foliage and 

 flowers, and dies 

 in autumn. Tlie 

 seal'is the circular 

 scar left by the death and separation of the base of the stout stalk from the 

 living rootstock. A? but one of these is formed each year, they mark 

 the limits of a year's growth. The bud at tlie end of the rootstock in the 

 figure (which w'as taken in summer) will grow the next spring into the 

 stalk of the seasou, which, dying in autunni, will 

 leave a similar scar, while another bud will be formed 

 farther ou, crr>wning the ever-advancing summit or 

 growing end of the stem. 



108. A? each year's growth of stem makes its 

 own roots, it soon becomes independent of the older 

 parts. A.nd after a certain age, a portion annually 

 dies off behind, about as fast as it increases at the 

 growing end, death following life with equal and cer- 

 tain step, with only a narrow interval. In vigorous 

 plants of Solomon's Seal or Iris, the living rootstock 

 is several inches or a foot in length ; while in the 

 short rootstock of Trillium or Birtliroot (Fig. 100) 

 life is reduced to a narrower span. 



109. An upriglit or short rootstock, like this of Trillium, is commonly 

 called a Caudex (93) ; or when more shortened and thickened it would 

 become a corm. 



110. A Tuber may be understood to be a portion of a rootstock thick- 

 ened, and with buds (eyes) on the sides. Of course, there are all grada. 

 tions between a tuber and a rootstock. Helianthus tuberosus, the so-called 

 Jerusalem Artichoke (Fig. 101), and the common Potato, are typical and 

 familiar examples of tlie tuber. The stalks by M^hich the tubers are at- 

 tached to tlie parent stem are at once seen to be dijTerent from tlie roots, 

 both in appearance and manner of growth. The scales on the tubers are the 

 rudiments of leaves ; the eyes are the buds in their axils. The Potato-plant 



Fia. 99. Root.stock of Solomon's Seal, with the bottom of the stalk of the sea- 

 son, anci the Imd for the iie.xt year'.s growth. 



Fig. 100. The very short rootstock and strong terminal bud of a Trillium or 

 Birthroot 



