X RUDIMENTS OP BOTANY. 



. Fibrous, a collection or bundle of fibres connected by a common 

 head and often merely by .the base of the stem ; as in the grasses. 



/. Fasciculated, when the fibres swell out slightly in the middle. 



g. Tuberous, a fibrous root bearing either at its neck or here and there 

 attached to its fibres one or more tubete, fleshy, and containing much 

 starchy feculent matter. These tubers are properly short subterranean 

 stems, containing usually eyes or buds from which new plants arise. 

 The root should be called tuberiferous. 



h. Granulated, a collection of small tubercles with eyes fit for the 

 reproduction of a plant, but not enveloped by cellular tissue filled 

 with starchy matter. 



i. Bulbous, consisting of a number of scales or coats closely applied 

 to each other, with a crown at the top and fibres below ; It performs 

 the 'office of a bud, and such roots may rather be termed bulbifcroua. 



12. The direction of the root is usually towards the centre of the 

 earth ; but it is sometimes contorted or bent upwards and downwards in 

 a zigzag manner ; or creeping when it proceeds laterally at right angles 

 from this. These have often been confounded with subterranean 

 branches ; the last of which only are troublesome to the agricultur- 

 alist. 



13. This is the part which springs upwards during the germination 

 of a seed ; it is the intermediate body between the root and the leaves. 



14. When the stem of a plant arising from a seed is evident, the 

 plant is termed caulescent ; and when not apparent or scarcely so, the 

 plants have received the name ofacaules, or stemlcss. 



15. When the stem instead of ascending, stretches either wholly or 

 in part, under ground, emitting here and there roots from below and 

 branches or leaves which rise upwards, it is called a rhizoma ; or if it 

 do not emit fibres, a cormus. Most of what Linmeus incorrectly de- 

 scribed as creeping roots are of the former description. 



16. Stolons or runners are long stems of a peculiar nature issuing 

 horizontally from a plant, and emitting only from the extremity roots 

 and leafy buds, as in the strawberry. 



17. The stem varies in structure, in three principal modes. 



18. In vascular plants it is either formed by successive additions to 

 the outside of the wood, when it is called Exogenous ; or by successive 

 additions to its centre, when it is called Endogenous. In cellular 

 plants it is formed by the union of the base of the leaves, or by a sim- 

 ple elongation or dilatation where no leaves or buds exist. 



19. The stem of Exogenous plants may be distinguished into the 

 pith, the medullary sheath, the wood, the bark, the medullary rays, 

 and the cambium. 



20. The pith is a mass of spongy cellular tissue occupying the centre 

 of the stem. 



21. The medullary sheath surrounds the pith, and consists of ipiral 

 vessels and ducts. It communicates on one side with ths pith and on 

 the other with the medullary rays, leaf buds and veins of the leaves. 



22. The wood lies upon the medullary sheath and consists of con- 

 centric layers, one of which is formed every year. These layers are 



