PROPAGATION BY SEPARATION AND DIVISION 63 



is mostly concerned with bulb-like and 

 corm-like organs, division operates 

 mostly with tubers, rootstocks, suckers 

 and various kinds of offsets. 



A tuber is a prominently thickened 

 portion of a root or stem, and it is 

 usually subterranean. The potato, 

 sweet potato and dahlia furnish good 

 examples. The stem-tuber, even if 

 underground, has more or less well- 

 marked eyes or buds, as the common 

 potato ; the word tube r is sometimes 

 restricted to thickened parts of stems. 



Tuberiferous plants 



are multiplied by plant- 



,, , , , FIG. 50. Oblong tubers 



ing these tubers Whole, under the crown of day-lily. 



or in many cases the 



tubers may be cut into small portions, as 

 described in Chapter V, in the descriptions of 

 cuttings. In hardy species, the tubers may 

 be allowed to remain in the ground over 

 winter, but they are generally dug in autumn 

 and stored in a dry and cold place, but where 

 they will not freeze. 



Tubers are of endless conformation. Often 

 they are fascicled underneath the crown of the 

 plant, as in the garden ranunculus and also in 

 the dahlia and day-lily (Fig. 50). They may 

 occur in long strings, as in the ground-nut or 

 apios. In the garden anemone (A. coronaria) 

 they are irregular and fantastic in shape. 

 FIG. 51. Pseudo- A special form of stem-tuber is the pseudobulb 

 bulb of orchid, (literally "false bulb") of many orchids (Fig. 



bearing a leaf at J . ' J . \ 



the top. 51). In some species, the pseudobulb is short 



