VI INTRODUCTION. 



§ 2. The Root. 



18. Roots ordinarily produce neither buds, leaves, nor flowers. Their branches, 

 called fibres when slender and long, proceed irregularly from any part of their surface. 



19. Although roots proceed usually from the base of the stem or stock, they may 

 also bo produced from the base of any bud, especially if the bud lie along the ground, 

 or is otherwise placed by nature or art in circumstances favourable for their deve- 

 lopment, or indeed occasionally from almost any part of the plant. They are then 

 often distinguished as adventitious, but this term is by some applied to all roots which 

 are not in prolongation of the original radicle. 



20. Roots are 



fibrous, when they consist chiefly of slender fibres. 



tuberous, when either the main root or its branches are thickened into one or 

 more short fleshy or woody masses called tubers (25). 



taproots, when the main root descends perpendicularly into the earth, emitting 

 only very small fibrous branches. 



21. The stock of a herbaceous perennial, or the lower part of the stem of an annual 

 or perennial, or the lowest branches of a plant, are sometimes underground and assume 

 the appearance of a root. They then take the name of rhizome. The rhizome may 

 always be distinguished from the true root by the presence or production of one or 

 more buds, or leaves, or scales. 



§ 3. The Stock. 



22. The Stock of a herbaceous perennial, in its most complete state, includes a 

 small portion of the summits of the previous year's roots, as well as of the base of the 

 previous year's stems. Such stocks will increase yearly, so as at length to form dense 

 tufts. They will often preserve through the winter a few leaves, amongst which are 

 placed the buds which grow out into stems the following year, whilst the under side of 

 the stock emits new roots from or amongst the remains of the old ones. These peren- 

 nial stocks only differ from the permanent base of an undershrub in the shortness of 

 the perennial part of the stems and in their texture usually less woody. 



23. In some perennials, however, the stock consists merely of a branch, which pro- 

 ceeds in autumn from the base of the stem either aboveground or underground, and 

 produces one or more buds. This branch, or a portion of it, alone survives the winter. 

 In the following year its buds produce the new stem and roots, whilst the rest of the 

 plant, even the branch on which these buds were formed, has died away. These annual 

 stocks, called sometimes hybernacula, offsets, or stolons, keep up the communication be- 

 tween the annual stem and root of one year and those of the following year, thus form- 

 ing altogether a perennial plant. 



24. The stock, whether annual or perennial, is often entirely underground or root- 

 like. This is the rootstock, to which some botanists limit the meaning of the term 

 rhizome. When the stock is entirely root-like, it is popularly called the crown of the root. 



25. The term tuber is applied to a short, thick, more or less succulent rootstock or 

 rhizome, as well as to a root of that shape (20), although some botanists propose to re- 

 strict its meaning to the one or to the other. An Orchis tuber, called by some a knob, 

 is an annual tuberous rootstock with one bud at the top. A potato is an annual tu- 

 berous rootstock with several buds. 



26. A bulb is a stock of a shape approaching to globular, usually rather conical 

 above and flattened underneath, in which the bud or buds are concealed, or nearly so, 

 under scales. These scales are the more or less thickened bases of the decayed leaves 

 of the preceding year, or of the undeveloped leaves of the future year, or of both. 

 Bulbs are annual or perennial, usually underground or close to the ground, but occa- 

 sionally buds in the axils of the upper leaves become transformed into bulbs. Bulbs 

 are said to be scaly when their scales are thick and loosely imbricated, tunicatcd when 

 the scales are thinner, broader, and closely rolled round each other in concentric layers. 



27 A corm is a tuberous rootstock, usually annual, shaped like a bulb, but in which 

 the bud or buds are not covered by scales, or of which the scales are very thin and 

 membranous. 



