Although our practice has been more extensive, and is more skillful,
in eating sweet potatoes than in raising them, we yet adventure some
remarks: No root can live and grow without food from the leaf; if the
tops be permitted to root, so much nutriment is subtracted from the
tubers as is diverted to these new roots. Those who are best skilled
in their cultivation, raise their vines up so as to detach the roots,
but do not twist them round the hill; which, by crushing or covering
the leaves, would render the vines unhealthy. As to vines of the
_Cucurbitacæ_, their fruit not being under ground, it is not necessary
that such an amount of prepared sap should go to the root as if tubers
were formed. There is, in such vines, a great liability to disease and
injury near the hill. The vines shrink and dry near the base; and
however flourishing the running end may otherwise be, it is destroyed.
If roots are secured at several points along the vine, we remove the
chances of its prematurely dying, without withdrawing any sap
necessary for the maturation of its fruit.