X INTRODUCTION. 



9. Riit roots under fiivortiblc cinumstanccs arc developed from other parts of 

 tlic plant. These are called Stcoiidary Roots. 



10. Anial Roots are those which spring from the stem or branches above 

 ground. In some, as in many Endogenous Plants, they proceed from the lower 

 joints of the stem ; in others, as the Mangroves and Fig-trees of Soutii Florida, 

 they descend from the branches, and at length, penetrating the soil, form new 

 stems in all respects similar to that of the parent tree. The tendril-like roots of 

 some climbing stems arc also of this class. 



11. Epiphiftc's or Air-Plants, of which the Tillandsia and Epidcndnim are ex- 

 amples, arc those which arc borne on the trunks or branches of trees, but draw 

 their nourishment from the air. 



12. Parasites, like Air-Plants, grow on other plants ; but tlicir roots, pene- 

 trating the substance of the supporting plant, feed upon its juices. Some, sis 

 the Mistletoe and Dodder, fix themselves upon the trunk or branches ; others, 

 like the Bccch-drop, upon the root. 



3. The Stem. 



1.3. The Stem, or Ascending Axis, is that part of the plant which grows up- 

 ward into the air and light, bearing leaves and flowers. It exists, under various 

 modifications, in all flowering plants ; but in those which arc said to be stemlcss 

 or acaulescent, it is very short, or concealed in the ground. 



14. It consists of a succession of leaf-bearing points, or Nodes, separated by 

 naked joints, or Internodes. The growing points, which are protected by reduced 

 leaves in the form of scales, are called Buds. These are termiiml, when they ter- 

 minate the axis ; axillarij, when they spring from the axil of the leaves ; that is, 

 from the point where the upper surface of the leaf joins the stem ; and adventi- 

 tious, when they are developed from any other part. 



15. Simple stems grow by the development of the terminal bud alone ; branch- 

 ing stems expand indefinitely from the axillary buds also. Tlic ultimate divis- 

 ions of the branches are called branchkts. 



16. The jointed stem of Grasses and similar plants is a Culm. 



17. Tiic thick and simple stem of the Palmetto is a Caudex. 



18. A Rliizoma, or Rootstock, is a perennial stem, commonly creeping on the 

 ground, or beneath its surface, developing annually a bud at the apex, while 

 the older portion decays. 



19. A Tuhrr is a subtcrranoan branch, excessively thickened by the deposition 

 of starchy matter, and furnished with minute scales, having concealed ijuds (eyes) 

 in their axils. 



20. A Corm is a solid globular subterranean .stem, tilled with starchy matter, 

 with a bud at the apex and roots below. 



21. A nnlb is n short subterranean stem, made up of the thickened bases of 

 leaves, in the form of persistent scales. It is tunicntrd or ro(it<d, when the scales 

 arc large and wnippcd one within the other; and sr«/i/, when these are small 

 and imitricntcfl. Small aerial bulbs, such as arc borne in the axil of the leaves 

 of the Ti^rcr-Lily, and among the flowers of the Onion, are called IhilUrln. 



22. A Stolon is a brancii wiiicli bends tu the earth, strikes root, and forms a 

 Dcw plant. 



