STATE HORTICULTURAL SOCIETY. 139 



pear at irregular intervals, and in no fixed order, as are the branches 

 of the stem. Unlike the hitter, they do not arise from buds ])revi- 

 ousl}^ and regularly formed. The root branches originate inside of 

 the bark, and, as in the seed, mechanically burst through the outer 

 envelope. This is very different from the external cellular protuber- 

 ance which forms the beginning of a bud destined to give rise to 

 a leafy branch of the stem. W hen roots are produced from the 

 stem, as in climbers, before spoken of, and sometimes in willows, 

 etc., in damp air, the origin is the same. The rudimentary rootlet 

 forms in the cambium layer, just beneath the bark, and forces its 

 way to the outside without order in arrangement or regularity of 

 number. Secondary roots branch like primaries, and so series after 

 series may be formed in a very complex and irregular system. 



Structure. — The root is characteristically different in structure 

 from that of the stem. It has no pith; all stems of the so-called 

 exogens, or outside growers, like our shrubs and trees, have this cen- 

 tral column of soft tissue. The root has no nodes or joints, as in all 

 stems. The extension in length comes about by the outstretching of 

 the tip, or, rather, of a short portion of the root near the tip. In the 

 stem joint after joint pushes out, not unlike the opening of a spy- 

 glass or telescope. — the lowermost extending first and carrying the 

 others upward with it. Leaves and buds in regular order occur on 

 the stem; no such appendages are found on the roots except as ad- 

 ventitious or accidental irregularities. Not unfrequently stems, 

 variously modified, normally grow beneath the soil, but they can 

 always be distinguished, by their structure and manner of growth, 

 from true roots. Thus the common potato (tuber) is formed at the 

 end of a white, thread-like, underground growth, which is sometimes 

 supposed to be a root, but any careful observer, without botanical 

 knowledge, may easily satisfy himself that it is a true stem in struc- 

 ture and growth. The tuber itself is only an enlarged part of this 

 sul)terranean stem. The so-called "eyes" are buds, and rudiments 

 of leaves, in the sha])e of little projections or scales, are sometimes 

 seen. The fleshy i)ortions of beets and parsnips are, on the other 

 hand, true roots, upon which "eyes" are not found. 



The tip of a root is a curious structure, wonderfully adapted for 

 the purpose it serves. It has just been said that the roots grow in 

 length by the elongation of the terminal portion, never by any 

 stretching of the main part of the structure. Now, all growing 

 vegeta))le tissue is very tender and delicate. We break off the grow- 

 ing part of an asparagus shoot and forever stop the extension of the 

 stem. As soon as the tissue becomes woody, increase in length for- 

 ever ceases. There is no such thing as the elongation of the trunk 

 of a tree, except as growth occurs at the top. Koots ])ush through 

 the soil, often with incredible force. How can the delicate, growing 

 end be thrust against hard substances without destruction? For the 

 stony soils of New England, })lows are armed with points of cast 



