TAPROOT

n. main root of a plant

A plant's taproot is a straight tapering root that grows vertically down. It forms a center from which other roots sprout.Plants with taproots are difficult to transplant. The taproot is why dandelions are hard to uproot — the top is pulled, but the long taproot stays in the ground, and re-sprouts.A taproot system contrasts to a fibrous root system, with many branched roots.
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Noun
1. (botany) main root of a plant growing straight downward from the stem
(hypernym) root
(classification) botany, phytology
2. something that provides an important central source for growth or development; "the taproot of his resentment"; "genius and insanity spring from the same taproot"
(hypernym) source, seed, germ

(n.)
The root of a plant which penetrates the earth directly downward to a considerable depth without dividing.
  

Synonyms and related words:
beginning, bulb, bulbil, commencement, conception, corm, derivation, genesis, grass roots, head, inception, origin, original, origination, provenience, radical, radicle, radix, rhizome, rise, root, rootstock, source, stem, stock, tap, tuber, tubercle