Forms of Stems 



SS 



I. Aerial Stems. 



a. The Runner.— Tliis is well seen in the Strawberry, where 

 a branch springing from a plant creeps along the ground (often 

 with a modified leaf or scale upon it), and ultimately strikes in 



the soil, producing 

 leaves and roots, and 

 forming a new plant 

 (fig. 78). 



Fig. 78. — Runner of Strawberry {Fragaria vesca). 



Fig. 79. — The oflset of 

 the Houseleek {Semper- 

 vivHiti), 



b. The offset, seen in the Houseleek, much resembling the 

 runner, but shorter and thicker (fig. 79). 



c. The stolon, as in the Gooseberry and Currant, is really 

 a branch given off above 

 the ground striking into the 

 earth and giving off roots 

 and leaves, forming a fresh 

 plant. This is often imitated 

 by gardeners in the process 

 of layering, when they bend 

 down a branch into the soil, 

 thus causing it to take root 

 and produce a fresh plant. 



d. The Sucker. — This 

 differs from the last in being 

 a branch springing from beneath the soil, and after proceeding 

 for a short time in a horizontal direction, giving off roots as it 

 does so, turns up and grows out of the ground, forming a new 

 plant. The Rose and Mint are examples. , 



2. Subterranean Stems. 



e. The rhizome or rootstock is a thickened stem creeping 

 either at the surface of the soil or just below it, giving off leaves 

 from the upper surface, and roots from the lower. As the 

 leaves fall off year by year, they leave scars marking where 



Fig. 80.— Stolon. 



