THE LIFE-HISTOKY OF PLAI^^TS. 



297 



Sucharis. Here there is no such marked intermis- 

 sion of growth ; the leaves do not wither periodi- 

 cally, and growth is relatively, at least, continuous. 

 Such hulbs are mostly natives of tropical or equa- 

 torial climates, where throughout the year there are 

 <!ontinuous moisture and continuous high tempera- 

 ture, with comparatively little fluctuation of climatic 

 <;onditions. It is clear that to dry up such bulbs 

 would be to weaken, probably kill them; hence 

 their roots should always be kept moist, and a 

 period of comparative rest secured by lowering the 

 temperature and diminishing, but 

 not entirely withholding, the water- 

 supply. 



The Bulb and the Flower. 



—The variations in bulb-conforma- 

 tion are, as already stated, numer- 

 ous, but in this place no further 

 mention need be made of them, ex- 

 cept it be to point out the difierent 

 positions of the flowers. In some 

 bulbs, like those of the Onion er of 

 the bulbous Irises, or Snowdrop, 

 the primary growing point of the 

 bulb ends in the production of a 

 flower or a head of flowers; con- 

 sequently any further growth in 

 that particular direction is put a 

 stop to, and any subsequent growth, 

 if it occur at all, must be from 

 below the point. A Tulip affords 

 another illustration of the same 

 kind. If a bulb be taken up in 

 summer after the flowering is over, 

 and when the leaves are commenc- 

 ing to wither, and it bo cut down 

 through the centre, the following 

 ■appearances may be seen. In the 

 ■centre is the lower part of the stalk which has borne 

 the flowers. From the lower part of this stalk emerge 

 the roots. On either side of the central column may 

 be seen one or more plump new buds, destined to con- 

 tinue the growth next season. These buds originate 

 from the base of the central column or stem, in the 

 axil of one or other of the scales — in fact, in precisely 

 the same way as before explained in the case of 

 axillary buds. (See ante, p. 199.) Outside these new 

 Tjuds may be seen two or three scales now dry or 

 rapidly shrivelling, which are the outer scales of 

 the original biilb. 



In this case, then, the original bulb flowers, makes 

 provision for the future, and then dies. The Tulip 

 of the present year is, therefore, not the same bulb 

 as that of the year preceding, but a direct descendant 

 irom it. 



yig. 27.— Section of Hyacinth, 



The Amaryllis, Hyacinth, and Narcissus have 

 bulbs of a different character (Fig. 27). In them 

 the primary growing point does not end in a flower, 

 but remains as a vegetative structure. The illustra- 

 tion at Fig. 27 does not clearly indicate the true 

 nature of the flower-spike, which appears to be, 

 but is not, terminal. The flower-stalks here are 

 truly axillary structures, coming off from the sides 

 of the bulb. As the older scales at the outside 

 and base of the bulb dry up and die, new growth 

 takes place in the terminal growing point, and so in 

 this case the bulb of the present 

 year is the direct continuation of 

 that of the year preceding. Vege- 

 tation is carried on by the renewed 

 growth of the same original grow- 

 ing point, but axillary growth also 

 takes place, for in general, not only 

 the flower-stalk, but numerous 

 lateral " offsets," will be produced 

 from such bulbs, and, indeed, it is 

 by such means that bulb-growers 

 multiply their stock. Mention has 

 also previously been made of ad- 

 ventitious buds, and of buds whose 

 dormant activity is called into life 

 by injury to the main stem. Bulbs 

 often supply illustrations of this 

 phenomenon, and one means of 

 multiplying bulbs of the Hyacinth 

 is to scoop out the lower part of 

 the bulb, or to cut it across in 

 various directions. Along the 

 edges of the wound a vast number 

 of small bulbules are formed, at first 

 consisting of scales only, but which 

 after two or three years' growth 

 produce flowers in the ordinary 

 way. 

 Another point may be alluded to as having a 

 bearing on practical cultivation, and that is the dif- 

 ference in the leaves of the bulbs and the alternation 

 of form and office which they present. It is hardly 

 necessary to say that the scales of a bulb and the 

 true leaves are essentially the same, the one being 

 merely a modification of the other. The position, 

 origin, and arrangement of the organs in question 

 would suf&ce to prove their identity, were it not ren- 

 dered even more obvious by the fact that the base of 

 the leaf is often fleshy, the free end foliaceous, thus 

 presenting both phases in one and the same organ. 

 Ordinarily, however, there is an alternation of 

 growth. First the bulb-scales are formed; these 

 are dep6ts of food-stores derived and accumulated 

 from the leaves of the parent bulb ; then the true 

 leaves appear within the scales, they lengthen, and 



