Roots are very different in different Plants: But ’tis not necessary here to take notice of all the nice Distinctions of them; therefore I shall only divide them in general into two Sorts, viz. Horizontal-Roots, and Tap-Roots, which may include them all.
All have Branchings and Fibres going all manner of ways, ready to fill the Earth that is open.
But such Roots as I call Horizontal (except of Trees) have seldom any of their Branchings deeper than the Surface or Staple of the Earth, that is commonly mov’d by the Plough or Spade.
The Tap-Root commonly runs down Single and Perpendicular[1] reaching sometimes many Fathoms below.
[1]In this manner descends the first Root of every Seed; but of Corn very little, if at all, deeper than the Earth is tilled.
These first Seed-Roots of Corn die as soon as the other Roots come out near the Surface, above the Grain: and therefore this first is not called a Tap Root; but yet some of the next Roots that come out near the Surface of the Ground, always reach down to the Bottom of the pulveriz’d Staple; as may be seen, if you carefully examine it in the Spring time; but this first Root in Saint-foin becomes a Tap Root.
This (tho’ it goes never so deep) has horizontal ones passing out all round the Sides; and extend to several Yards Distance from it, after they are by their Minuteness, and earthly Tincture, become invisible to the naked Eye.
A Method how to find the Distance to which Roots extend Horizontally.
[Pl. 6. Fig. 7.] Is a Piece or Plot dug and made fine in whole hard Ground, the End A 2 Feet, the End B 12 Feet, the Length of the Piece 20 Yards; the Figures in the middle of it are 20 Turneps, sown early, and well ho’d.
