62 THE VEGETATIVE ORGANS 



have removed. Such shoots are called adventitious shoots. 

 Some shrubs and trees often produce adventitious shoots 

 from horizontal root-branches, e.g. Raspberry (Fig. 27), 

 Rose, Bramble, Hawthorn, Poplar, and Hazel. Shoots 

 arising in this manner from roots are called suckers. 



Roots vary greatly in their duration : they may be 

 annual, a fresh crop being produced each season ; biennial, 

 living two years only ; or perennial, living for many years. 

 Even among perennials, some roots, such as those of bulbs 

 and corms, often live only one season ; the bulb of one 

 season dying away and leaving an offshoot or bud to con- 

 tinue growth which forms roots of its own. 



Tuberous roots of Lesser Celandine. -The Lesser Celan- 

 dine has roots which show some specially interesting 

 features. The plant flowers in the early spring. Some- 

 times it grows in open, sunny places and receives frequent 

 visits from insects, but often in wet, shady hollows in woods, 

 where insects are scarce and fewer seeds are set. The 

 plants growing under such conditions should be carefully 

 studied. We have already seen (p. 60) that this plant 

 produces two kinds of roots (Fig. 28). From what part of 

 the plant do the tubers spring ? How do they grow ? How 

 is the compact cluster of tubers formed ? Of what uses are 

 the tubers to the plant ? 



Take a few seedlings (Fig. 28, 2, 3, 4) and note the coloured 

 scale (sc) at the base and the small green foliage-leaf. In 

 the axil of the scale a tuber (t) is formed, which bursts 

 through it and grows parallel to the root (r). Later, a 

 young shoot elongates, uses up the food- reserves in the 

 tuber, and forms one or more leaves (I) . In the axils of these 

 leaves new tubers develop, and may often be found to elon- 

 gate and turn sharply over the edge of the sheathing-base 

 on their way to the soil (1, t). Examine them closely, and 

 note that they are clothed with root-hairs, especially when 

 growing in damp air. If a transverse section is examined, 



