46 PRACTICAL BOTANY. 



lateral branches are developed, are polygonal. Its sur- 

 face is studded by stiff hairs, which are especially 

 obvious on the lower portions of the internodes. 



The stem bears laterally numerous Leaves, which 

 are simple, petiolate, 1 cordate-acuminate, the margin 

 slightly serrate, ciliated, venation palmate-reticulate, 

 the surface hirsute. The arrangement of the leaves at 

 the lower part of the plant (and including the 

 cotyledons which wither at an early stage), is opposite, 

 or in whorls of three ; higher up this arrangement 

 merges into the alternate, the complication increasing 

 constantly upwards. 



The stem is terminated by a bud, which may con- 

 sist only of closely aggregated foliage leaves (or it 

 may inclose the reproductive organs, which are 

 contained in numerous flowers, closely aggregated so 

 as to form a characteristic inflorescence the capitulum, 

 (cf. infra). Similar buds, in earlier stages of develop- 

 ment, may be observed in the axils of the leaves 

 (axillary buds). 



Wash the roots and examine them. They are 

 fibrous, and branch profusely. The primary (tap) root 

 and earlier developed lateral roots are thicker than the 

 later developed roots of a higher order (cf. secondary 

 thickening of roots), the latter being successively 

 thinner. 



II. Cut the stem of a well-grown plant transversely at 

 its thickest part, and smooth the surface with a razor. 



The most prominent object in the section will be the 

 massive, white, spongy Pith which occupies the centre. 



1 N.B. The form of the leaves varies, the lower leaves of the plant 

 being cordate, the upper ones lanceolate with winged petiole. 



