SECT. I 



MORrHOLOGY 



25 



serving hs a reservoir of reserve material, while the leaves are thin 

 and scaly. Of such tubers those of the Meadow Satiron {Colchicum 

 autumnale) or of Crocus sativus are good examples. In the Meadow 

 Saffron new tubers arise from axillary buds near the base of the 

 modified shoot, but in the Crocus from buds near the apex. In 

 consequence of this, in the one case the new tubers appear to grow 

 out of the side, and in the other to spring from the top of the old 

 tubers. The tubers of the Potato (Fig. 26) or of the Jerusalem 



XS' 



Fig. 25. — Longitudinal Fio. 20.— Part of a growing Potato plant, Solanum tuberomm. The 



section of Tulip bulb, whole plant has been developed from the dark-coloured tuber 



Tulipa Gesneriana. zk, in the centre. (From nature, copied from one of Haii.lon's 



Modifie<l stem ; zs, scale illustrations, J nat. size.) 



leaves ; v, terminal bud ; , 



k, rudiment ot a young 

 bulb ; w, roots. (Nat. 

 size.) 



Artichoke {Helianthus tuherosus) are also subterranean shoots with 

 swollen and reduced leaves. They are formed from the ends of 

 branched, underground shoots or runners (stolons) and thus develop 

 at a little distance from the parent plant. The so-called eyes on the 

 outside of a potato, from which the next year's growth arises, are in 

 reality axillary buds, but the scales which represent their subtending 

 leaves can only be distinguished on very young tubers. The parent 

 plant dies after the formation of the tubers, and the reserve food 

 stored in the tubers nourishes the shoots which afterwards develop 

 from the eyes. Since, in their uncultivated state, the tubers of the 



