SECTION 6.] STEMS. 43 



they grow ; from their consisting of a succession of joints ; and from the 

 (eaves which they bear ou each node, in the form of small scales, just like 

 the lowest ones on the upright stem next the ground. They also pro- 

 duce buds in the axils of these scales, showing the scales to be leaves ; 

 whereas real roots bear neither leaves nor axillary buds. Placed as 

 they are in the damp and dark soil, such stems naturally produce roots, 

 just as the creeping stem does where it lies on the surface of the 

 ground. 



105. It is easy to see why plants with these running rootstocks take 

 such rapid and wide possession of the soil, and why they are so hard to 

 get rid of. They are always perennials ; the subterranean shoots live over 

 the first winter, if not longer, and are provided with vigorous buds at every 

 joint. Some of these buds grow in spring into upright stems, bearing 

 foliage, to elaborate nourishment, and at lengbh produce blossoms for re. 

 production by seed ; while many others, fed by nour- 

 ishment supplied from above, form a new generation 

 of subterranean shoots ; and this is repeated over and 

 over in the course of the season or in succeeding 

 yeai's. Meanwhile, as the subterranean shoots in- 

 crease ill number, the older ones, connecting the suc- 

 cessive growths, die off year by year, liberating the 

 already rooted side-branches as so many separate plants ; and so on indefi- 

 nitely. Cutting these running rootstocks into pieces, therefore, by the hoe 

 or the plough, far from destroying the plant, only accelerates the propaga- 

 tion ; it converts one many-branched plant into a great number of separate 

 individuals. Cutting into pieces only multiplies the pest ; for each piece 

 (Fig. 98) is already a plantlet, with its roots and with a bud in the axil of 

 its scale-like leaf (either latent or apparent), and with prepared nourishment 

 enough to develop this bud into a leafy stem ; and so a single plant is all the 

 more speedily converted into a multitude. Whereas, when the subterra- 

 nean parts are only roots, cutting away the stem completely destroys 

 the plant, except in the rather rare oases where the root freely produces 

 adventitious buds. 



106. Rootstocks are more commonly thickened by the storing up of 

 cousiderable nourishing matter in their tissue. The common species of 

 Iris (Fig. 164) in the gardens have stout rootstocks, which are only partly 

 covered by the soil, and which bear fohage-leaves instead of mere scales, 

 closely covering the upper part, while the lower produces roots. As the 

 leaves die, year by year, and decay, a scar left in the form of a ring marks 

 the place where each leaf was attached, that is, marks so many nodes, 

 separated by very short internodes. 



107. Some rootstocks are mai'ked with large round scars of a different 



PiQ. 98. A piece of the running rootstook of the Peppermint, with its node oi 

 joint, and an axillary bud ready to grow. 



