THE BULB BOOK 



(either as bulbs, corms, tubers, or rhizomes) decay and die, they are 

 replaced by new ones. If it were not so, especially in our climate, 

 there would be great danger in many cases of the plants dying out 

 altogether — especially as many of them are difficult or impossible to 

 raise from seeds. AVhen there seems to be any risk of a plant being 

 unable to reproduce itself readily by means of seeds, Nature has 

 endowed it with the power of multiplying itself in other ways which 

 are considered under the Chapter on " Propagation." 



The point to bear in mind, however, at present is that the new 

 bulbs, corms, tubers, or rhizomes underground can only be produced 

 by the healthy assimilative action of the leaves, and the absorptive 

 powers of the roots. 



CONTRACTILE EOOTS 



In connection with the annual reproduction of new corms in 

 such plants as Crocus, Gladiolus, etc., it is interesting to notice 

 a very extraordinary action of the roots. During the period of 

 growth if a corm of a Grladiolus or Tritonia (Fig. 19) be taken out of 

 the ground carefully it will he noticed that there are two kinds of 



roots present — (1) the fibrous 

 feeding or absorbing roots, and 

 (2) thicker ringed roots. The 

 latter play a very important 

 part in keeping the new corms 

 at a proper distance beneath the 

 surface of the soil. It is obvious 

 that by the superposition of the 

 new corms on top of the old ones 

 year after year, there would be 

 a danger eventually of them 

 coming througli the surface of 

 the ground. They would thus be 

 exposed to the dangers of frost, 

 etc. It is well known, however, 

 that neither corms nor bulbs, no 

 matter how many years they 

 have been in the soil, ever come through the ground. On the 

 contrary, they seem to bury themselves deeper and deeper, thus 

 keeping away from the frost, and in surroundings several degrees 

 warmer than the soil immediately at the surface. 



Fio. 19.— Tritonia Pottsi, showing new corms 

 and contractile roots. 



