Visual identification of small oilseeds and weed seed contaminants - Individual species

Descriptions and drawings for individual species

Domestic mustard seed

Brassica juncea (L.) Czern. et Coss. - oriental mustard

Common Name: oriental mustard

Family Name: Brassicaceae (syn. Cruciferae)

Brassica juncea

Shape:

  • outline - oval, obliquely-oval
  • hilum end may be broadly flattened at an angle
  • seed may be flattened longitudinally from the hilum to apex such that the radicle is along one side.
  • the radicle groove ranges from almost non-existent to broad and shallow to broad and deeper (crease-like)
  • the radicle may lay flat with the surface of the seed or lie below the edges of the cotyledons or may bulge slightly beyond

Colour:

  • yellow to dark yellow with a small percentage of brown seeds

Seed Surface:

  • prominent reticulations
  • distinctly netted with fine, prominent, cord-like lines over the entire seed surface
  • netting remains prominent right up to the hilum
  • interspaces are large and flat with small stipples contained within
  • hilum with a flush or slightly raised white linear ridge on a circular area that is the same colour or slightly darker than the seed coat

Size:

  • length 1.6-3 mm, width 1.2-2.1 mm (approximate sizes)

Common Name: brown mustard

Family Name: Brassicaceae (syn. Cruciferae)

Shape:

  • outline - spherical or oval, seed tends to roll
  • occasionally hilum area slightly flattened
  • occasionally seed may be flattened longitudinally from the hilum to apex
  • the radicle area less distinct than in other Brassica species, generally non-existent or groove broad and shallow

Colour:

  • light brown to dark reddish brown

Seed Surface:

  • reticulations, netting, and interspaces same as oriental mustard above
  • hilum with a flush or slightly raised white linear ridge on a dark brown or black circular area

Size

  • 1.5-2 mm in diameter

Reference Number:

  • 6
Sinapis alba L. - yellow mustard

Common Name: yellow mustard (white mustard)

Synonym: Brassica hirta Moench., Brassica alba Boiss.

Family Name: Brassicaceae (syn. Cruciferae)

Sinapis alba L. - yellow mustard

Shape:

  • seeds may be flat at the hilum end
  • seeds may be flattened longitudinally from the hilum to apex such that the radicle area is along one side
  • radicle groove ranges from non-existent to a broad shallow groove to a prominent raised radicle ridge

Colour:

  • light creamy yellow to yellow

Seed Surface:

  • faintly reticulated
  • reticulations are usually partially obscured by a thick waxy surface
  • reticulation lines wide and flat
  • interspaces very small and shallow with no stipples
  • overall appearance is like an orange peel
  • hilum is a small white spot in a deep yellow or light tan circular area

Size:

  • diameter 2.0-3.0 mm

Reference Number:

  • 5

Canola and Rapeseed

Brassica napus L. - canola or rapeseed

Common Name: canola or rapeseed

Family Name: Brassicaceae (syn. Cruciferae)

Brassica napus

Shape:

  • outline - approximately spherical, obliquely-spherical, squarish
  • seeds generally broadly flat at the hilum end
  • seeds may be flattened longitudinally from the hilum to apex such that the radicle is along one side
  • radicle groove ranges from almost non-existent to broad and shallow to broad and deep (crease-like) where the cotyledons are distinctly spread apart by the groove
  • the radicle may be slightly raised within this groove or may lay flat within it

Colour:

  • reddish (especially when immature), grey, grey-black, black

Seed Surface:

  • faintly reticulated, may be barely discernable
  • interspaces small and shallow
  • small shiny stipples cover the seed surface for an overall granular or sugary appearance
  • hilum with a flush or slightly raised white linear ridge; on lighter coloured seeds this linear scar may be seen to partially bisect a darker coloured circular area that is slightly convex

Size:

  • length 1.1-2.6 mm, width 1.3-2.3 mm

Reference Number:

  • 2, 5
Brassica rapa L. – canola quality

Common Name: canola

Synonym: Brassica campestris L.- previously used to refer to Polish rapeseed, but currently Brassica campestris is only used with reference to wild forms of this species

Family Name: Brassicaceae (syn. Cruciferae)

Brassica rapa

Shape:

  • outline - oval, oblong, obliquely-oblong, occasionally spherical
  • hilum end may be slightly flattened
  • seeds frequently flattened longitudinally from the hilum to apex such that the radicle is along one side
  • radicle groove ranges from almost non-existent to faint and shallow to deep and well defined
  • the radicle may lay flat with the surface of the seed or lie below the edges of the cotyledons or may bulge prominently beyond

Colour:

  • mixed colours including yellow, yellow-brown, red-brown, red-grey, dark brown and mottled colours

Seed Surface:

  • seeds are reticulated but in some cases reticulation is faint or obscured
  • interspaces medium size and slightly concave
  • small shiny stipples cover the seed surface
  • appears lightly netted and moderately granular
  • hilum with a flush or slightly raised white linear ridge; ridge is within a slightly convex darker coloured (light brown to black) circular area; white ridge not always present on yellow coloured seeds

Size:

  • approximate: length 1.5-2 mm

Reference Number:

  • 5

Brassica rapa L. – rapeseed quality

Common Name: Polish rapeseed

Shape:

  • as above

Colour:

  • red-brown, grey, grey-black; these varieties do not contain yellow seeds

Seed Surface:

  • as above, generally reticulations are obvious to distinct

Size:

  • approximate: length 1.5-2 mm

Reference Number:

  • 5

Weed seeds

Sinapis arvensis L - wild mustard

Common Name: wild mustard, charlock

Synonym: Brassica kaber L.(D.C.) L.C. Wheeler

Family Name:Brassicaceae (syn. Cruciferae)

Sinapis arvensis - wild mustard

Shape:

  • outline - spherical, occasionally immature seeds are oval
  • occasionally seeds will be slightly off-shaped with slightly flattened areas due to crowding in the seed pod

Colour:

  • highly variable; tan, orange-brown, red-brown, brown, grey, black
  • hilum area may be a different colour than the rest of the seed
  • occasionally seeds may be distinctly two different colours (eg. orange/black)

Seed Surface:

  • general appearance is smooth with no radicle ridge or groove
  • actually finely reticulated or faintly granular
  • reticulations may appear as faint striations that radiate from the hilum in a sunburst pattern
  • hilum linear; white, even with the seed surface or slightly raised
  • on lighter coloured seeds hilum may run into a very small, dark, circular area

Size:

  • diameter 1.3-1.7 mm

Reference Number:

  • 5, 6
Galium aparine / spurium L. - cleavers

Common Name: cleavers (Galium aparine L.) false cleavers (Galium spurium L.)

Family Name: Rubiaceae

Galium aparine/spurium - cleavers

Remarks:

The two cleavers species of concern in small oilseed crops are Galium aparine and Galium spurium. For seed identification purposes there are limited features that distinctly separate these two species, and given that both species are undesirable, they are often placed together as Galium aparine / spurium and called cleavers.

Shape:

  • outline - spherical, oval or kidney shaped (side view)
  • one side of the seed is rounded and the other side has a depression in the centre; the seed is almost hollow through this depression

Colour:

Outer Surface

  • aparine - grey, greyish-brown, buff, brown; spurium - brown, grey-brown

Inner Surface

  • if the spines are rubbed off the inner seed surface is golden-brown to brown

Seed Surface:

Outer Surface:

  • surface of both species covered with stiff hooked spines 0.2mm (spurium) to 0.8mm (aparine) long
  • spines arise from small tubercles on the seed coat (aparine) or directly from the seed coat (spurium)
  • both species may have smooth seeds but this is less common

Inner Surface:

  • nearly smooth, lightly netted

Size:

  • variable - the two species overlap
  • diameter (excludes spines): aparine 1-4 mm, spurium 1.2-2.5 mm

Reference Number:

  • 1, 6, 8
Vaccaria hispanica L. - cow cockle

Common Name: cow cockle

Synonym: Saponaria vaccaria L.

Family Name: Caryophyllaceae

Vaccaria hispanica - cow cockle

Shape:

  • outline - roughly spherical
  • usually with a broad shallow depression on both sides of the hilum which may extend around the seed

Colour:

  • black
  • when immature may be orange to reddish-brown

Seed Surface:

  • covered with small tubercles which give the seed a rough spiky appearance
  • tubercles more or less regular in arrangement
  • surface appears dull, however when magnified the tips of the tubercles are often shiny
  • hilum concave, circular to oval in shape (looks like a small open mouth)
  • hilum may have small remnants of whitish seed stalk attached

Size:

  • diameter 2.0 to 2.7 mm

Reference Number:

  • 5, 6
Neslia paniculata (L.) Desv. - ball mustard

Common Name: ball mustard

Family Name: Brassicaceae (syn. Cruciferae)

Neslia paniculata - ball mustard

Remarks

The seed unit of ball mustard most often found is actually a nutlet, which is a dry indehiscent fruit (illustrated) containing one seed. The actual seed without the shell may be found on occasion.

Shape:

Fruit:

  • outline - broadly oval, heart-shaped
  • oval in cross-section
  • a ridge runs from the hilum to the apex where the two halves of the nutlet join together
  • apex usually comes to a fine point with a tiny circle at the tip
  • hilum is small, squarish-oval to circular in shape; hilum may be somewhat sunken with slightly flared edges

Seed:

  • outline - oval
  • radicle thick and forms a prominent ridge in the radicle groove
  • radicle tip frequently extends beyond the hilum

Colour:

Fruit:

  • buff, grey, grey-brown; surface may be tinged green orpurple

Seed:

  • yellow to yellowish-brown
  • there is a distinct, reddish-brown circular spot near the hilum

Seed Surface:

Fruit:

  • prominently netted; interspaces are concave, broad and shallow
  • ridges and interspaces covered with small wart-like protuberances
  • overall appearance is coarsely granular

Seed:

  • faintly wrinkled, almost smooth
  • slightly shiny

Size:

  • Fruit: length 2.2-2.5 mm, width 2.5-2.8 mm
  • Seed: length 1.9-2.2 mm, width 1.0-1.3 mm

Reference Number:

  • 2, 5, 6, 10
Descurainia sophia (L.) Webb. - flixweed

Common Name: flixweed

Family Name: Brassicaceae (syn. Cruciferae)

Descurainia sophia - flixweed

Shape:

  • outline - obliquely oblong to obliquely obovate
  • flattened in cross-section
  • on each seed face a longitudinal groove starts at the radicle tip and runs approximately one-third the distance from the long edge of the seed outlining the radicle
  • this groove often curves at the apex and travels back towards the hilum
  • the radicle tip is even with or extends slightly past the hilum
  • whitish seed stalk remnant may be attached at hilum

Colour:

  • golden to bright red-orange

Seed Surface:

  • finely reticulated in a distinct regular ladder-like mesh pattern in parallel rows
  • shiny or oily looking

Size:

  • length 0.8 - 1.2 mm, width 0.4 - 0.6 mm

Reference Number:

  • 5, 9, 10
Descurainia richardsonii (Sweet) O. E. Shultz. - gray tansy mustard

Common Name: gray tansy mustard

Family Name: Brassicaceae (syn. Cruciferae)

Descurainia richardsonii - gray tansy mustard

Shape:

  • outline - irregular, obliquely oblong or obliquely obovate
  • somewhat flattened in cross-section
  • on each seed face a longitudinal groove starts at the radicle tip and runs approximately one-third the distance from the long edge of the seed outlining the radicle
  • this groove often curves at the apex and travels back towards the hilum
  • radicle tip extends beyond the hilum
  • radicle may appear twisted
  • hilum end notched, frequently with white seed stem tissue attached
  • apex often comes to a slightly rounded point

Colour:

  • dark reddish brown; hilum end darker, almost black

Seed Surface:

  • distinctly reticulated with a honeycomb pattern
  • overall roughened appearance; oily

Size:

  • length 0.9-1.1 mm, width 0.4-0.7 mm

Reference Number:

  • 5
Capsella bursa-pastoris (L.) Medick. - shepherd’s-purse

Common Name: shepherd’s-purse

Family Name: Brassicaceae (syn. Cruciferae)

Capsella bursa-pastoris - shepherd’s-purse

Shape:

  • outline - oblong to obovate
  • uniformly flattened in cross-section
  • on each seed face a longitudinal groove starts at the radicle tip and runs approximately one-third the distance from the long edge of the seed outlining the radicle
  • this groove often curves at the apex and travels back towards the hilum
  • the seed may have the appearance of being drawn-in at the hilum end like a pouch
  • hilum end notched, often with white seed stem tissue attached

Colour:

  • dark reddish-brown to golden red-brown
  • hilum end is usually noticeably darker - may appear

Seed Surface:

  • finely netted
  • appears roughened

Size:

  • length 0.9 - 1.2 mm, width 0.4 - 0.6 mm

Reference Number:

  • 6
Sisymbrium altissimum L. - tumble mustard

Common Name: tumble mustard

Family Name: Brassicaceae (syn. Cruciferae)

Sisymbrium altissimum - tumble mustard

Shape:

  • outline - variable, but usually oblong and often angled, seems boxy
  • somewhat flattened in cross-section
  • long edges of seed nearly parallel
  • at the hilum the edges are slightly pinched together; a slight white seed stalk remnant may be attached
  • the apex is squarish
  • one seed face is flattened or slightly curved; the opposite side is oftenangled such that if the seed is placed on one of the parallel edges the seedslopes length-wise from the centre towards each end (looks like a roof)
  • on each seed face there is a longitudinal groove (deeper on the angled face) outlining the radicle

Colour:

  • yellow-brown, light brown, greenish-yellow, greenish-brown
  • the groove and edges of the seed are often outlined in dark green or purplish lines; this colouring may also appear as speckles beneath the seed surface

Seed Surface:

  • granular appearance, greasy looking

Size:

  • length 0.8 to 1.1 mm x width 0.5 to 0.6 mm

Reference Number:

  • 5, 6, 10
Erysimum cheiranthoides L. - wormseed mustard

Common Name: wormseed mustard

Family Name: Brassicaceae (syn. Cruciferae)

Erysimum cheiranthoides - wormseed mustard

Shape:

  • outline - variable; irregular, obliquely oblong or obliquely obovate
  • radicle ridge frequently twisted
  • prominent radicle ridge outlined by a distinct groove
  • radicle tip extends beyond the hilum
  • hilum end frequently with white seed stem tissue attached
  • apex often comes to a point

Colour:

  • yellow to orangy- or reddish- brown
  • hilum end darker, almost black

Seed Surface:

  • almost smooth; faintly reticulated or faintly granular
  • often dull

Size:

  • length 1.0-1.4 mm, width 0.3-0.6 mm

Reference Number:

  • 5, 10
Erucastrum gallicum (Willd.) O. E. Shultz - dog mustard

Common Name: dog mustard

Family Name: Brassicaceae (syn. Cruciferae)

Erucastrum gallicum - dog mustard

Shape:

  • outline - oval to obovate
  • not flattened, oval and plump in cross-section on each seed face a longitudinal groove starts at the radicle tip outlining the radicle
  • this groove may curve at the apex and travel back towards the hilum
  • groove not always prominent
  • radicle may form a prominent ridge
  • hilum end notched and frequently with white seed stem tissue attached

Colour:

  • golden brown, red brown, light brown
  • hilum end darker in colour

Seed Surface:

  • reticulated with an irregular net pattern
  • granulation visible in the interspaces

Size:

  • length 1.0-1.2 mm, width 0.6-0.8 mm

Reference Number:

  • 6
Thlaspi arvense L. - stinkweed

Common Name: stinkweed, field pennycress

Family Name: Brassicaceae (syn. Cruciferae)

Thlaspi arvense - stinkweed

Shape:

  • outline - oval, ovate or obovate
  • flattened in cross-section
  • on each face a narrow groove extends through the middle from the hilum to approximately half-way down the seed
  • hilum is notched and gives the appearance of a slightly open beak
  • slightly elongated at hilum
  • remnant of white seed stem tissue frequently attached

Colour:

  • dark reddish-brown to black
  • slightly glossy or iridescent

Seed Surface:

  • covered with distinct concentric ridges or loops like a fingerprint
  • these ridges and the spaces between them are transversely pitted giving a roughened appearance

Size:

  • length 1.6-2 mm, width 1.1-1.4 mm

Reference Number:

  • 5, 6, 10
Conringia orientalis (L.) Dumort. - hare’s-ear mustard

Common Name: hare’s-ear mustard

Family Name: Brassicaceae (syn. Cruciferae)

Conringia orientalis - hare’s-ear mustard

Shape:

  • outline - roughly oval or oblong
  • radicle thick and forms a prominent ridge; this ridge is outlined by a groove that extends to the apex
  • the tip of the radicle extends beyond the cotyledons at the hilum end
  • a prominent whitish seed stalk remnant often remains attached

Colour:

  • reddish-brown to dark brown
  • may have a bronzy-orange surface layer that settles in the grooves and pits

Seed Surface:

  • appears roughened and granular
  • when magnified this surface has a distinctive pattern of pits that appears as circles within circles

Size:

  • Length 2.2-2.8 mm, width 1.0-1.3 mm

Reference Number:

  • 6, 10
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