. The elements of structural . ce of the latter kind, and any weed willserve to illustrate the former. The Beech and theCurrant have iioody stems, while the weeds are hcTcLercoHs. Between the Beech and the Currant the chiefdifference is in size. The Beech is a tree, the Currant aslu-ub. But you are not to suppose that there is a hardand fast line between shrubs and trees, or between Jierbsand shrubs. A series of plants could be constructed,commencing with an unquestionable herb, and end-ing with an unquestionable tree, but embracing plantsexhibiting such a gradual transition from her
. The elements of structural . ce of the latter kind, and any weed willserve to illustrate the former. The Beech and theCurrant have iioody stems, while the weeds are hcTcLercoHs. Between the Beech and the Currant the chiefdifference is in size. The Beech is a tree, the Currant aslu-ub. But you are not to suppose that there is a hardand fast line between shrubs and trees, or between Jierbsand shrubs. A series of plants could be constructed,commencing with an unquestionable herb, and end-ing with an unquestionable tree, but embracing plantsexhibiting such a gradual transition from herbs tosluubs, and from shrubs to trees, that you could notsay at what precise point in the series the changesoccurred. 90. The forms assumed by stems above ground arenumerous, and they are described mostly by terms incommon use. For instance, if a stem is weak, andtrails along tJie ground, it is ttailiim, or prostrate : and if, as in the run-ners of the Straw-berry, it takesroot on the lowe-vside, then it iscreepnu). Manyweak stems raise. ELEMENTS OK STRirCTURAL BOTANY. 67 themselves by clinging to any suppoii that may happento be within theii- reasli. In some iiistancts the stemitself winds round the support, assuming a spiral form,as in the Morniug-Glory, the Uop, and the Bean, andis therefore distinguished as twining. In other casesthe stem puts forth thread-like leafless brandies calledtendrils (Fig. 97), which grasp thesupport, as in the Vii-giuia Creeper,the Grape, and the Pea (Fig. 98), orsometimes the leaf-stalks serve thesame purpose, as .in the Clematis orVirgins Bower. In these cases thestems are said to climb. The stems of wlicat and grassesgenerally are known as cnhm*. Theyare jointed, and usually hollow exceptat the joints. Fig. oa 91. Besides the stems which grow above ground, there
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectbotany, bookyear1879
