# Radicle

> The embryonic root, the first structure to emerge from a germinating seed, which grows down to become the primary root or taproot.

- Canonical: https://genetixbay.com/knowledge/glossary/radicle.html
- Also written: embryonic root, seed root, first root, taproot tip
- Glossary category: Plant biology · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

The radicle is the embryonic root. It is the first organ to break out of the [seed coat](https://genetixbay.com/knowledge/glossary/seed-coat.md) during [germination](https://genetixbay.com/knowledge/glossary/germination.md), and it grows straight down under gravity to become the [primary root](https://genetixbay.com/knowledge/glossary/taproot.md) (the taproot). [Root hairs](https://genetixbay.com/knowledge/glossary/root-hair.md) form just behind its tip within a day or two.

## In practice

When growers say a seed has "popped" or "tailed", they mean the radicle is out. Plant it once it is about 5-20 mm (0.2-0.8 in) long, tip down, roughly 5-10 mm deep. Longer tails are fragile and easily snapped; a broken radicle tip often stops or badly delays the [seedling](https://genetixbay.com/knowledge/glossary/seedling.md). Handle by the shell, never the root.

The radicle and its fine root hairs dry out in minutes in open air. Move quickly from paper towel or water to medium, and keep the medium moist, not [waterlogged](https://genetixbay.com/knowledge/glossary/overwatering.md).

## Don't confuse with

- **Taproot**: the mature primary root that the radicle becomes.
- **Hypocotyl**: the shoot-side stem segment that lifts the [cotyledons](https://genetixbay.com/knowledge/glossary/cotyledon.md); it emerges after the radicle.
- **Root hairs**: tiny single-cell outgrowths on the radicle, not separate roots.

## Related terms

[Taproot](https://genetixbay.com/knowledge/glossary/taproot.md), [Hypocotyl](https://genetixbay.com/knowledge/glossary/hypocotyl.md), [Seed coat](https://genetixbay.com/knowledge/glossary/seed-coat.md), [Root hair](https://genetixbay.com/knowledge/glossary/root-hair.md)

## Read more

- [Germination methods compared: soak, paper towel, plugs, direct sow](https://genetixbay.com/knowledge/germination/germination-methods.md)
- [Transplanting: when, into what, and avoiding transplant shock](https://genetixbay.com/knowledge/germination/transplanting.md)

## Sources

1. Small E. 2015. Evolution and classification of Cannabis sativa (marijuana, hemp) in relation to human utilization. The Botanical Review 81:189-294. https://doi.org/10.1007/s12229-015-9157-3