298 



CASSELL'S POPULAE GARDEXIXG. 



in theiz' turn acquire and elaborate food for the next 

 generation of bulbs. In the Hyacinth and bulbs of 

 that character there are, from what has been said, 

 numerous generations of leaves, first scaly and acting 

 as food-stores, next leafy and acting as food-getters 

 and food-formers. In the Tulip, on the other hand, 

 owing to its mode of growth, there are but two 

 generations of leaves — the first scaly, the next leafy — 

 and then there is an end to the growth of the plant, 

 so far as that generation is concerned. The subse- 

 quent alternations of scale and leaf 

 manifest themselves not in the 

 primary bulb, which wears itself 

 out in the production of flowers 

 and succession buds, but in those 

 secondary buds. 



We have here illustrated two 

 phenomena of plant-growth, which 

 are repeated in other organs, but to 

 which we desire to call attention 

 here on account of the very marked 

 manner in which they are mani- 

 fested. These two phenomena are 

 (1) the alternate production of 

 modifications of the same organs, 

 these modifications being adapted 

 to serve distinct pur|)oses ; and (2) 

 the " indefinite " and " definite " 

 modes of growth respectively. "We 

 shall see later on that where the 

 main flower-stalk ends in a flower 

 (as in the Tulip), there is no further 

 growth at the end of that stalk; 

 growth there is arrested or defined 

 by the production of a flower ; but 

 where the growing point at the 

 extremity of a stem does not end in 

 a flower, growth in length goes on 

 " indefinitely." 



The remarks made as to the 

 nature and mode of growth of bulbs apply, with 

 slight modification, to other underground organs 

 acting as store-houses of food or starting-points of 

 growth, such as " corms," " tubers," " root-stocks," 

 or "rhizomes," and the like. Indeed, although in 

 most cases it is easy to give satisfactory definitions 

 of these organs, yet they sometimes run one into 

 another in such a way that accurate definition be- 

 comes impossible. These are matters, however, 

 which do not greatly concern us from the point of 

 view of practical cultivation. If only the general 

 principles of their growth and of the work they 

 have to do be grasped, the varied details of their con- 

 formation may be left to the botanist. We may, 

 however, fitly allude to some of the commoner and 

 best-known forms above mentioned. 



Fig. 28.— Corm of Crocus, with 

 new growths issuing from 

 the top of the old one. 



Corms. — As usually understood, corms or *' solid 

 bulbs," as they are also called, differ from bulbs in 

 this, that the scales on the outside are dry and few 

 in number, while the base or lower part of the stem 

 from which they spring is greatly dilated. The 

 depot of nutriment in this case is therefore in the 

 stem, not in the scales. 



The Crocus and the Gladiolus afford familiar 

 examples of the corm. Their mode of growth is 

 the same as to general principles as that of the biilbs. 



Tbe Gladiolus, for instance, aft'ords 

 an illustration of a terminal corm ; 

 the main stem ends in the inflo- 

 rescence which, together with the 

 old conn, withers after flowering, 

 lea ring a lower bud of axillary 

 origin to carry on the growth in 

 the next season. A Gladiolus corm 

 examined in the spring of the year 

 shows the withered remnants of 

 the old corm, surmounted by the 

 new one, from the base of which 

 proceed the roots. On remoring 

 the base of the sheathing leaves, 

 small buds may be seen in the axil, 

 which will not flower this season, 

 but in a subsequent one. 



In the Crocus the new corms 

 formed in spring are developed 

 from the top of the old corm, as 

 shown in Figs. 28 and 29. They are 

 for a longer time dependent on the 

 old corm than in the case of the 

 Gladiolus, as may be seen by the 

 fact that roots proceed from the 

 base of the new corm in spring, 

 while at the same period, in the 

 case of the Crocus, there are no 

 roots yet produced from the new 

 corm, the withering old corm still 

 retaining its roots. " Every living part of a Crocus," 

 says Mr. Maw, " is annually replaced. The corm 

 tunic is the only permanent record of perennial 

 existence, and even this in its living state lasts but a 

 year." The general mode of growth is thus essen- 

 tially similar to that already mentioned in the case of 

 the Tulip. Considering, then, the short time that a 

 Crocus has wherein to develop its flowers, its leaves, 

 and its successional corms, the folly of cutting off 

 the leaves prematurely becomes the more apparent. 



Tubers. — For our present purpose we may con- 

 sider a tuber to be a thickened shoot, without any 

 investing scales, but with one or more " eyes," that 

 is, buds. In a bulb or a corm the central stem from 

 which the scales and leaves proceed is short and 



