ee FLOWERING PLANTS 
Stem of | With the Sunflower may be compared a twig of 
Lime. the Lime, or Elm, or Oak, or any woody stem. A 
twig three or four years old should be chosen; the age of a 
twig can be told by noticing the scars left by the scales of the 
buds of each year (“ Elementary Botany,” p. 15). Cut a twig 
of the Lime across, and observe with the naked eye, as before. 
The same tissues are observable as in the Sunflower, but it will 
_ be seen at a ere that the fibro-vascular tissue does not occur 
ee Ct isetitcd 
| : ~~ bundles, as in 
the Sunflower; 
instead of that 
a cylinder of 
wood has been 
formed. It 
will be easy | 
| 40 recognise 
| the three 
rings of wood, 
corresponding 
to the three 
years of 
growth, and 
the medullary 
Fic. 19.—Srem or Turer-YEar-Onp Twie Lime, thewood. In 
TRANSVERSE SECTION. (Low power.) 
this stem the 
ck, cork; 6, bast; w, wood; », pith ; eb, position 
of cambiun ; M.1, medullary rays. greater part 
of the section 
is occupied with the wood; the pith is much less than in 
the Sunflower, considering the size of each. Beneath 
the outer skin may be seen a yellowish tissue, which is 
cork, : 
Course of ‘I'he course of the fibro-vascular bundles through 
te the stem must next be considered. It is easier to 
Tissue. . trace them out in the Dead-nettle than in the Sun- 
flower, for they are less complicated, but even in the Dead- 



