INTRODUCTION 
The Root 
The seed is a relatively small structure which remains almost 
unchanged for some considerable time, long enough at least to bridge 
over the unfavourable season for plant-life above ground, whether that 
season be the cold and drought of winter, or the heat and drought of a 
dry summer season. When supplied with the requisite amount of heat, 
moisture, and air, the seed sprouts, and in so doing it puts out first its 
rudimentary root or radicle and then its primary shoot or plumule. We 
will, therefore, briefly consider the parts of a Flowering Plant in the 
order of their development in the life-cycle of a new generation : root, 
shoot, stem, leaves, flower, fruit, seed. 
The primary root is the descending portion of the axis of the plant ; 
it generally has a strong tendency to grow downwards, i.e. towards the 
centre of gravity, and it bears, as a rule, neither buds nor 
leaves. When underground, as it generally is, it does not 
become green ; its growth in length takes place a little behind its apex, 
and this growing-point is protected by a root-cap of dead cells. If the 
radicle, or rudimentary root of a sprouting seed, grow downward with a 
tapering form and few if any branches, it is termed a tap-root and may 
assume various forms, such as the conical root of the Carrot, the napiform 
root of the Turnip (Latin napus , a turnip), or the spindle-shaped roots of 
some Radishes. 
If the root branches, its branches closely resemble the main root: 
they force their way out through the outer tissues of the main root, being, 
therefore, known as endogenous (Greek h ;8ov, endon, within ; yewdw, gennao , 
I produce) ; those first formed ( secondary roots') being given off in regular 
vertical rows from the base of the parent primary root ( ie . its junction 
with the stem) towards its apex, whilst those formed later are in no regular 
order, or, as it is termed, adventitious. A much-branched tap-root, such as 
that of the Wallflower, or a tuft of unbranched adventitious roots, such 
as those of Grasses or of bulbs, are alike spoken of as Jibrous roots. 
The slender branches of roots are called rootlets. Adventitious roots may 
be given off from stems, as in the Ivy and in bulbs, or from the cut ends 
of cuttings, or even in some cases from leaves. 
xv 
