4 



INTRODUCTORY. 



feed upon the juices of other plants), the roots adhere to or penetrate 

 the plants upon which they feed, either above-ground, as the Mistletoe 

 and Dodder, or they attach themselves to their roots beneath the surface, 

 as in the various root-parasites. Roots branch without any regular order, 

 and very seldom produce buds, in which they differ from the 



12. Stem or Ascending Axis. As the elongation of the radicle 

 lifts the cotyledons of the bean, &c., above the surface of the earth, so 

 in turn the plumule or little bud is lifted up ; its leaves, or leaf, as the 

 case may be, expand, another bud is produced, and thus the process goes 

 on, and the plant increases in length by the developement of a succes- 

 sion of leaves separated by a greater or less length of stem. The point 

 on the stem from which a leaf, or leaves, arise is termed a iVorfe (or knot) 

 and the spaces between the nodes are Internodes (or joints) . A stem is 

 made up of leaf-bearing internodes and terminated by a bud, which is a 

 collection of very short internodes with their undeveloped leaves. The 

 nature of the bud is seen in a marked manner in some trees in which 

 the whole of the next season's growth may be seen in miniature, just as 

 the first internode of the plant is found in the seed. 



13. A stem which continues to develope from the apex only, remains 

 simple ; but commonly the stem branches. Branches proceed from buds 

 which with few exceptions, appear on the stem in the angle formed by 

 its union with the leaf (the axil). The position of the branches is deter- 

 mined by that of the leaves, and did all the buds develope, the form of 

 the plant would be regular. Sometimes buds appear out of their usual 

 place, (the axils of the leaves) and as roots may develope from any part 

 of the stem, so under some circumstances may buds. Such buds are 

 termed adventitious ; they may even appear on the root, which does not 

 ordinarily produce buds. Where more than one bud appears in an axil, 

 the additional ones are called accessory ; and where, as is sometimes the 

 case, buds appear above the axil, they are extra-axillary. When the 

 stem continues to elongate by the terminal bud and the main trunk is 

 kept distinct, as in the Fir Trees, the stem is excwrent ; but it is usual- 

 ly lost in the branches, when it is deliquescent. 



14. If a stem of a plant dies down at the end of the season, it is an 

 Herb. Herbs, according to the duration of their roots, may be annual, 

 biennial or perennial (9) ; where the stem becomes woody it is, according 

 to its size, a Shrub or Tree. Under-slirubs are woody plants with stems 

 rising but little above the surface of the ground. If the stem is only 

 woody near the base it is suffruticose ; or when but little woody, suffrutes- 

 cent. Shrubs and Trees differ only in size ; those under 15 or 20 feet 

 high and branching from near the ground are called shrubs. The 

 jointed stem of grasses is called a Culm. 



15. The various modifications of the stem and branches have received 

 distinguishing names, of which the most used are given here. When the 

 stem is too weak to stand erect but bends over, it is declinei; if it partly 

 lies on the ground, it is decumbent ; or if it lies entirely upon the ground, 

 prostrate or procumbent. If it clings to objects by means of tendrils 

 (16), like the Grape vine, or by aerial roots (11), like the Ivy, it i;i 



