242 Of the Roots of Plants. 
parted at bottom, as moft roots; others at top, as dande¬ 
lion, Sec. fome parted and ramified, as comfrey ; others 
having divers firings iffuing from one head, as crowfoot; 
fome ftrait as raddifh, crooked as biftort, fmooth as bu- 
glofs, ftringy all round as columbine ; fome thick as rhu¬ 
barb, (lender as the vine, long as fennel, fhort as turnep. 
Sec. he. 
The motions of roots are fometimes perpendicular, as 
parfnip, level as hops, ammi, cinquefoil, he. 
There is a kind of wreathing or twilling in the veffels 
of fome when the bark is ftripped off, in carduus, fon- 
chus, he. in which may be fometimes feen two or three 
circumvolutions. 
But the moft remarkable of all roots are fuch as are an¬ 
nually renewed or repaired out of the trunk or ftalk itfelf, 
as arum, rape-crowfoot, valerian, brownwort, bearsfoot, 
tanfy, lychnis, fapier, primrofe, ammi, avens, wood-for- 
rel, iris, and others ; that is to fay, the bafis of the ftalk 
continually and by infenfible degrees, defeending below 
the furface of the earth, and hiding itfelf therein, is both 
in nature, place, and office, changed into a root. So in 
brownwort the bafis of the ftalk finking down by degrees 
till it lies under ground, becomes the upper part of the 
root; and continuing ftiil to fink, the next year becomes 
the lower part, and the next after that rots away, s a 
new addition being yearly made out of the ftalk, as the 
older parts annually rot away. 
In a difiedlion of the root we lhall firft find the lkin, 
next the cortical, which when thin is commonly called 
the bark; next within this are the woody fibres, which 
together with all its parts,-are vifible in a circle; its pores 
feeing nothing near fo numerous as that of the cortical, 
but in fome more open than in others, as may be feen on 
cutting 
1 Grew. Anat. of Plant, p. 59. 
