Definitions

rootlet

Taproot

[tap-root, -root]

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 presence of a 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.

Most trees begin life with a taproot, but after one to a few years the main root system changes to a wide-spreading fibrous root system with mainly horizontal growing surface roots and only a few vertical, deep anchoring roots. A typical mature tree 30–50 m tall has a root system that extends horizontally in all directions as far as the tree is tall or more, but well over 95% of the roots are in the top 50 cm depth of soil.

Many taproots are modified into storage organs.

Some plants with taproots:

Development

Taproots develop from the radicle of the seed, which forms the primary root. It produces branches called the secondary roots, and they in turn produce branches to form tertiary roots. These may further branch to form rootlets.

Typical taproots

  • Conical root: this type root tuber is conical in shape, i.e. broad at the base and tapering gradually towards the apex: e.g. carrot.
  • Fusiform root: this root is swollen in the middle and tapers towards the base and the apex: e.g. radish.
  • Napiform root: the root has a top-like appearance. It is very broad at the base and tapers suddenly like a tail at the apex: e.g. turnip.

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