Growth and Development of Rapid-Cycling Brassicas Labeled

One fast mustard plant from seed to seed, then its flower up close.

Growth and Development of Rapid-Cycling Brassicas Labeled

Name Date

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Write the name of each numbered stage or part.Answer key

  1. Seed
  2. Radicle (first root)
  3. Cotyledons (seed leaves)
  4. Hypocotyl
  5. True leaves
  6. Roots
  7. Flower buds
  8. Flowers
  9. Bee (pollinator)
  10. Seed pods (siliques)
  11. Petal
  12. Sepal
  13. Pistil
  14. Stigma
  15. Long stamens
  16. Short stamens
  17. Anther
  18. Nectary

Drawn for this site on 2026-10-03 from plain curves. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a stage or part is answered.

Next step Next: the organs of a whole plant

All 18 stages and parts on the diagram

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Seed to plant 6

  1. Seed A seed holds a tiny new plant, the embryo.
  2. Radicle (first root) The first root to come out of the seed. It grows down.
  3. Cotyledons (seed leaves) The two seed leaves. They were already inside the seed.
  4. Hypocotyl The stem below the seed leaves. It lifts them out of the soil.
  5. True leaves The leaves that grow after the seed leaves. They form at the stem tip.
  6. Roots They hold the plant in the soil and take in water.

Flower to seed pod 4

  1. Flower buds Flowers that have not opened yet. Sepals cover each one.
  2. Flowers Open flowers, each with four petals in a cross.
  3. Bee (pollinator) It carries pollen from one plant to another.
  4. Seed pods (siliques) Long narrow fruits with the seeds inside. Each grew from one pistil.

The flower 8

  1. Petal One of the four petals. Together they make a cross.
  2. Sepal One of the four sepals. They covered the flower in bud.
  3. Pistil The part in the middle that becomes the seed pod.
  4. Stigma The tip of the pistil, where pollen must land.
  5. Long stamens The four tall stamens, next to the pistil.
  6. Short stamens The two outer stamens. They are shorter than the other four.
  7. Anther The top of a stamen. It makes the pollen.
  8. Nectary A small gland that makes nectar, the sweet food bees come for.

How this list was compiled: Every name checked on 2026-10-03 and kept only where two of these use it. (1) University of Wisconsin-Madison, the program that breeds these plants and teaches with them: The Seed Challenge (a teaching booklet) and Bees and Brassicas (1987), https://fastplants.org/pdf/activities/seed_challenge.pdf and https://fastplants.org/pdf/activities/bees_brassicas.pdf : a seed holds a tiny new plant, the embryo, inside a seed coat; in germination the seed soaks up water and swells till its coat cracks; first the root emerges, then the stem with two seed leaves, also called cotyledons; true leaves grow; root hairs; flower buds appear at the growth tip, each protected by four sepals; a flower has four petals, one pistil and six stamens, four long and two short, each anther with pollen; nectaries deep inside the flower produce nectar; bees carry pollen from plant to plant, and the plants do not self-pollinate; the pistil swells into the seed pod, or fruit, which holds several seeds; when the seeds have dried they can start another life cycle. (2) Wikipedia, Brassicaceae, Silique, Brassica rapa, Hypocotyl, Cotyledon, Seedling, Germination and the article on this cultivar, https://en.wikipedia.org/wiki/Brassicaceae , https://en.wikipedia.org/wiki/Silique , https://en.wikipedia.org/wiki/Brassica_rapa , https://en.wikipedia.org/wiki/Hypocotyl , https://en.wikipedia.org/wiki/Cotyledon , https://en.wikipedia.org/wiki/Seedling , https://en.wikipedia.org/wiki/Germination , https://en.wikipedia.org/wiki/Wisconsin_Fast_Plants : four free sepals, four petals with a blade and a claw, six stamens in two whorls, the two lateral outer ones shorter than the four inner ones; nectaries on the receptacle opposite the base of the lateral stamens; one superior pistil with a globular stigma; the fruit is a silique, a capsule more than three times as long as wide whose two outer walls separate when ripe and leave a partition; seed leaves entire or with a notch at the tip; the radicle emerges first; the hypocotyl is the stem of a seedling below the cotyledons, and it pushes through the soil pulling the cotyledons with it; true leaves form after germination; bees, flies and butterflies visit the flowers; a relative of the turnip and bok choy bred for a very short life cycle. (3) C. S. Gager, Fundamentals of Botany, 1916 (public domain), sections 340, 384 and 412, https://archive.org/details/fundamentalsofbo00gagerich : the embryo-stem (hypocotyl) carries the first leaves (cotyledons) above the soil while the first root (radicle) develops; in a germinating seed the hypocotyl elongates and draws the cotyledons out of the ground; the four petals of the mustard family form a cross, and its fruit is a silique; the family includes mustard, radish, cabbage and turnip. (4) Asa Gray, Manual of the Botany of the Northern United States, fifth edition, 1867 (public domain), the mustard family and the genus Brassica, https://archive.org/details/manualofbotany00gray : sepals 4; petals 4, their spreading limbs forming a cross; stamens 6, two of them inserted lower down and shorter; the pod is divided by a thin partition from which the valves separate when ripe, and a pod much longer than broad is a silique; the seed is filled by the embryo, and in Brassica the cotyledons are folded around the radicle. Licence: own work

The drawing: Drawn for this site on 2026-10-03 from plain curves; own work, nothing traced. Licence: own work

How it works

The growth and development of rapid-cycling brassicas labeled in three drawings: a seed sprouts into a seedling, the plant flowers and is pollinated, and its seed pods ripen. One generation takes only weeks.

Read the full guide

From seed to seed

The seed soaks up water and its coat cracks. The radicle, the first root, comes out first. Then the hypocotyl lifts the two cotyledons, the seed leaves, above the soil, and true leaves grow. Flower buds form at the tip of the stem and open. A bee carries pollen from one plant to another. The pistil of a pollinated flower swells into a long seed pod, a silique, and the seeds ripen inside.

The flower

Each flower has four sepals, four petals, one pistil and six stamens: four long and two short. Nectaries at the foot of the short stamens make nectar.

  • These plants do not pollinate themselves. The pollen has to come from a different plant.
  • How fast the plants grow depends on light and warmth.

Questions and answers

What are rapid-cycling brassicas?

Small plants of the mustard family, a kind of Brassica rapa bred to go from seed to seed in a few weeks under classroom lights. The turnip and bok choy are close relatives.

What are the stages of growth and development of a rapid-cycling brassica?

Germination, growth of the seedling and its true leaves, flower buds, flowering and pollination, then seed pods that swell and dry. The ripe seeds start the cycle again.

What are cotyledons?

The two seed leaves a seedling opens first. They were already inside the seed. True leaves grow later, from the tip of the stem.

How many stamens does a brassica flower have?

Six: four long ones next to the pistil and two short ones outside them. Each ends in an anther, which makes the pollen.

What is a silique?

The seed pod of the mustard family: a long, narrow fruit. When it is ripe and dry, its two outer walls come away from a thin wall in the middle.

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