CHAPTER IX. 



NON-TYPICAL SHOOTS. 



Creeping shoots Super-terranean types Subterranean types 

 Rhizomes Monopodial rhizomes Bracken and others As- 

 cending rhizome of Primrose Sympodial rhizomes Thick 

 rhizomes as food reservoirs Thin rhizomes ; stolons or soboles 

 Subterranean stem-tubers Potato Other tubers Arum 

 Corms of Crocus, Colchicum, Cyclamen, and Ranunculus bulbosus 

 --Bulbs Pseudo-bulbs of epiphytic orchids Shoots in aquatic 

 plants Rhizomes Stolons Submerged shoots with or without 

 floating leaves Lemna-type Types of Pistia, Aldrovandia, 

 and Salvinia Succulent plants Succulent stems in Cactaceae, 

 Euphorbia and Stapelia Succulent leaves. 



A SECOND class of non-typical shoots are characterised 

 by their habit of creeping away from the centre formed by 

 the parent plant or root, and pushing their terminal buds 

 some distance in a radial direction from the already 

 occupied and exhausted area from which they started. 

 This they may do simply along the surface of the ground, 

 as in the case of the runners of the Strawberry, Ranun- 

 culus repens, Hieracium Pilosella, Ground Ivy, &c., or 

 beneath the surface as in the Rhizomes of Carex, Yellow 

 Flag, Equisetum, Bracken Fern, &c. The creeping Willow, 

 Salix repens, does either or both. 



In both sets of cases the object attained is to develope 



82 



