Symphyotrichum laeve var. laeve

  • Genus

    Symphyotrichum

  • Family
    Asteraceae
  • Synonyms

    Aster laevis

    Aster falcidens

    Aster laevis var. falcatus

    Aster steeleorum

    Symphyotrichum var. concinnum

    Symphyotrichum var. geyeri

    Symphyotrichum var. pupuratum

    Read More
  • Common names

    Smooth blue aster

    Blue aster

    Smooth-leaved aster

    Glaucous Michaelmas-daisy

    Glaucous aster

    Read More

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Purity

  • ISTA PSD

    4

    See Details
  • AOSA PSU

    28

    See Details
  • Purity working weight (grams)

    0.75

    See Details
  • Other species (OSD)/Noxious working weight (grams)

    7.5

    See Details

PSU 28

Intact achene, whether or not a seed is present, with or without one or more of the following structures: beak, bristle, hairs, pappus, or wing.

Piece of broken achene larger than one-half of the original size, unless no seed is present.
Seed, with or without pericarp/seed coat.
Piece of broken seed, with or without pericarp/seed coat, larger than one-half the original size.

TWS Notes

PSD 4

Achene, with or without beak, pappus or bracts, including achenes where two or more seed units are joined together by fused pericarps, unless it is obvious that no seed is present.

Piece of achene larger than one-half the original size, unless it is obvious that no seed is present.

Seed, with the pericarp/testa partially or entirely removed.

Piece of seed larger than one-half the original size, with the pericarp/testa partially or entirely removed.

TWS Notes

Purity working weight (grams)

Noxious working weight/OSD

Germination and dormancy breaking method

Media

 Agar 1%, Top blotter or paper

Moistened with

 H2O

Prechill

 No

Other dormancy breaking recommendations

Check for dormancy of firm ungerminated seeds at the termination of the test, using the basic criteria indicated in the Tetrazolium section below.

Germination Temperature

 25°C

Hours light/dark

 8/16

Days in warm germ

 28

Germination Image Gallery

Description of Normal/Abnormal Seedlings:

Seedlings will be evaluated as normal when they have the essential structures that will have the ability to produce a plant growing in favourable conditions. Seedling conditions present (singly or in combination), which would cause the seedling to be evaluated as abnormal (not considered viable):

Cotyledons: less than half of the original cotyledon healthy tissue remaining attached.

Epicotyl: missing (considered present if cotyledons are intact).

Hypocotyl: open lesions extending into conducting tissue. Shortened curled or thickened.

Root: None, weak stubby or missing primary root even with weak secondary roots.

Seedling: Albino seedling is abnormal. Primary infection in one or more essential structures. Consider infection to be secondary if seedling is well developed and normally balanced (Normal).

Modified Germination:

Test can be terminated at 14 days if the dormancy is checked with tetrazolium at the termination of the germination test.

Tetrazolium (TZ) Methodology Recommendations:

  • Imbibition method and time

    Imbibe overnight between moist media or immersed in water

  • Option(s) to prepare and cut seed for staining

    Cut into seed on cotyledon end slightly into cotyledon

  • Percentage (%) of TZ solution

    1.0

  • Time and temp of staining (hr)

    4 hours up to overnight if needed

  • List of important seed structures requiring staining:
    Radicle tip may be staining darker or lighter than the cotyledons. The seed is also considered normal if less than ½ unstained area of the cotyledons are away from the hypocotyl/cotyledon point of attachment.

TZ Methodology Gallery

  • Abnormal - Radicle not well stained
  • Normal - borderline - 1/2 cotyledon stained
  • Normal
  • Normal