Brassica rapa

Field mustard has been cultivated for over 4,000 years.
Photo Credit: © Jim Stasz, USDA-NRCS PLANTS Database.
Brassica rapa
Common Name: field mustard
Other Common Names: bird's rape, birdsrape mustard, rape, rape mustard, turnip rape, wild mustard, wild rutabaga, wild turnip
Plant Functional Group: Forb
Class > Order > Family: Magnoliopsida > Brassicales > Brassicaceae
What does the species look like?

Field mustard is an annual to biennial, herbaceous plant growing 8 to 36 inches tall, with large plants being highly branched in the upper half of the plant. Its small, yellow flowers have both male and female parts, and are grouped into somewhat showy clusters at the top of each stem. The flowers are insect-pollinated.

Field mustard is a cultivated species, but has escaped into some areas; it is found in cropland, weedy fields, travel corridors, and waste areas. It generally prefers a cool climate, with full sunlight, moist to dry conditions, and a neutral to alkaline soil containing loam, clay-loam, or gravelly material. It is resistant to frost and mild freezes.
Where is the species found?
States & Provinces
AB, AK, AL, AR, AZ, BC, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MB, MD, ME, MI, MN, MO, MS, MT, NB, NC, ND, NE, NH, NJ, NL, NM, NS, NT, NV, NY, OH, OK, ON, OR, PA, PE, QC, RI, SC, SD, SK, TN, TX, UT, VA, VT, WA, WI, WV, WY, YT
Special Considerations for Observing

If drought seems to be the cause of leaf senescence for a plant, please make a comment about it for that observation.
Which phenophases should I observe?
Do you see...?
Leaves Initial growth
New growth of the plant is visible after a period of no growth (winter or drought), either from above-ground buds with green tips, or new green or white shoots breaking through the soil surface. Growth is considered "initial" on each bud or shoot until the first leaf has fully unfolded. For seedlings, "initial" growth includes the presence of the one or two small, round or elongated leaves (cotyledons) before the first true leaf has unfolded.
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Leaves
One or more live, fully unfolded leaves are visible on the plant. For seedlings, consider only true leaves and do not count the one or two small, round or elongated leaves (cotyledons) that are found on the stem almost immediately after the seedling germinates. Do not include fully dried or dead leaves.
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Flowers Flowers or flower buds
One or more fresh open or unopened flowers or flower buds are visible on the plant. Include flower buds or inflorescences that are swelling or expanding, but do not include those that are tightly closed and not actively growing (dormant). Also do not include wilted or dried flowers.
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How many flowers and flower buds are present? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), simply estimate the number of flower heads, spikes or catkins and not the number of individual flowers.

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • More than 1,000
Open flowers
One or more open, fresh flowers are visible on the plant. Flowers are considered "open" when the reproductive parts (male stamens or female pistils) are visible between or within unfolded or open flower parts (petals, floral tubes or sepals). Do not include wilted or dried flowers.
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What percentage of all fresh flowers (buds plus unopened plus open) on the plant are open? For species in which individual flowers are clustered in flower heads, spikes or catkins (inflorescences), estimate the percentage of all individual flowers that are open.

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Pollen release
One or more flowers on the plant release visible pollen grains when gently shaken or blown into your palm or onto a dark surface.
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How much pollen is released?

  • Little: Only a few grains are released.
  • Some: Many grains are released.
  • Lots: A layer of pollen covers your palm, or a cloud of pollen can be seen in the air when the wind blows

Fruits Fruits
One or more fruits are visible on the plant. For Brassica rapa, the fruit is a slender capsule that changes from green to yellow or tan and splits open to expose the seeds. Do not include empty capsules that have already dropped all of their seeds.
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How many fruits are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • More than 1,000
Ripe fruits
One or more ripe fruits are visible on the plant. For Brassica rapa, a fruit is considered ripe when it has turned yellow or tan and has split open to expose the seeds. Do not include empty capsules that have already dropped all of their seeds.
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What percentage of all fruits (unripe plus ripe) on the plant are ripe?

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more
Recent fruit or seed drop
One or more mature fruits or seeds have dropped or been removed from the plant since your last visit. Do not include obviously immature fruits that have dropped before ripening, such as in a heavy rain or wind, or empty fruits that had long ago dropped all of their seeds but remained on the plant.
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How many mature fruits have dropped seeds or have completely dropped or been removed from the plant since your last visit?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • More than 1,000
What do these phenophases look like?

There is currently no photoguide available for this species. If you'd like help us create one, use the guidance document and species template provided here. Then send it via email to education@usanpn.org when it is complete.

USDA PLANTS profile for field mustard (USDA Symbol: BRRA )