Knotweed family, Polygonaceae

Kinds of seed: Buckwheat, rhubarb, and sorrel.

(a) General description.

(1) Germination habit: Epigeal dicot.

(2) Food reserves: Cotyledons, starchy endosperm.

(3) Shoot system: The hypocotyl elongates carrying the cotyledons above the soil surface. The epicotyl usually does not show any development within the test period.

(4) Root system: A primary root, with secondary roots developing within the test period for some kinds.

(b) Abnormal seedling description.

(1) Cotyledons:

(i) Less than half of the original cotyledon tissue remaining attached.

(ii) Less than half of the original cotyledon tissue free of necrosis or decay.

(2) Epicotyl:

(i) Missing. (May be assumed to be present if cotyledons are intact.)

(ii) [Reserved]

(3) Hypocotyl:

(i) Deep open cracks or grainy lesions extending into the conducting tissue.

(ii) Malformed, such as markedly shortened, curled, or thickened.

(iii) Watery.

(4) Root:

(i) None.

(ii) Weak, stubby, or missing primary root with weak secondary or adventitious roots.

(5) Seedling:

(i) One or more essential structures impaired as a result of decay from primary infection.

(ii) Albino.

[59 FR 64506, Dec. 14, 1994]