THE STEM OR SHOOT. 



123 



yellow loosestrife (Lysimachia vulgaris) and laid it 

 prostrate on moist soil, when it became changed into a 

 rhizome which grew downwards into the soil. 



He also induced the development of a runner at the 

 apex of the inflorescence of the bugle {A jug a reptans) 

 and the ground-ivy (Glechoma). 



Duchartre gives an account of a plant of Lilium 

 neilgherrense whose bulb gave rise to a shoot which at 

 first grew horizontally or slightly downwards in the 

 soil for a certain distance, behaving exactly like a 

 rhizome, bearing scale-leaves and adventitious roots, 

 and eventually grew vertically upwards above the soil 

 in the usual way. 



2. Erect Shoots. — The converse case is frequent in 

 which shoots, normally prostrate or creeping, become 

 erect, either congenitally or at a later period of life. 

 In the fastigiate varieties of trees, e. g. Lombardy 

 poplar (Populus nigra var. italica), Irish yew (Taxus 

 baccataY&r.fastigiata), and Exeter elm (JJlmus montana 

 var. fastigiata), all the lateral branches grow erect and 

 parallel with the main stem. There is a variety of the 

 spruce (Picea, excelsa) in which on a strong lateral shoot 

 a number of erect daughter-shoots arise; the Germans 

 call this form " liarfenfichte " (harp-spruce). There 

 are other forms again which have many " leaders " 

 instead of one. 



In many trees, as in the Coniferse, it is easy, by 

 excision of the leader, to cause a lateral, normally 

 dorsiventral branch to assume an erect terminal position 

 and radial symmetry. 



Main trunks which have fallen over and lie prostrate 

 often produce on their upper side lateral shoots which 

 grow vertically upwards as their parent stem did 

 previously. Many trees and shrubs whose lateral 

 branches are normally of dorsiventral character, with 

 distichously-arranged leaves, can be induced, by ex- 

 cision of the " leader," or, as in the case just cited, by 

 changing its position, to form lateral shoots of radial 

 symmetry bearing scattered leaves. 



