Kinds of seed: Artichoke, cardoon, chicory, dandelion, endive, great burdock, lettuce, safflower, salsify, Louisiana sagewort, and sunflower.
(a) Lettuce.
(1) General description.
(i) Germination habit: Epigeal dicot.
(ii) Food reserves: Cotyledons which expand and become thin, leaf-like, and photosynthetic. The cotyledons of some varieties develop elongated petioles.
(iii) Shoot system: The hypocotyl elongates and carries the cotyledons above the soil surface. The epicotyl usually does not show any development within the test period.
(iv) Root system: A long primary root.
(v) Seedling: The interpretations of lettuce seedlings are made only at the end of the test period.
(2) Abnormal seedling description.
(i) Cotyledons:
(A) Less than half of the original cotyledon tissue remaining attached.
(B) Less than half of the original cotyledon tissue free of necrosis or decay. (Remove attached seed coat for evaluation of cotyledons. Physiological necrosis is manifested by discolored areas on the cotyledons and should not be confused with natural pigmentation of some lettuce varieties.)
(ii) Epicotyl:
(A) Missing. (May be assumed to be present if cotyledons are intact.)
(B) Any degree of necrosis or decay.
(iii) Hypocotyl:
(A) Deep open cracks extending into the conducting tissue.
(B) Severely twisted or grainy.
(C) Watery.
(iv) Root:
(A) Stubby or missing primary root. (Secondary roots will not compensate for a defective primary root.)
(B) Primary root tip blunt, swollen, or discolored. (Toxic materials in the substratum may cause short, blunt roots; see § 201.58(a)(9).)
(C) Primary root with splits or lesions.
(v) Seedling:
(A) Swollen cotyledons associated with extremely short or vestigial hypocotyl and root.
(B) One or more essential structures impaired as a result of decay from primary infection.
(C) Albino.
(b) Other kinds in the sunflower family: Artichoke, cardoon, chicory, dandelion, endive, great burdock, safflower, salsify, Louisiana sagewort, and sunflower.
(1) General description.
(i) Germination habit: Epigeal dicot.
(ii) Food reserves: Cotyledons which expand and become thin, leaf-like, and photosynthetic.
(iii) Shoot system: The hypocotyl elongates and carries the cotyledons above the soil surface. The epicotyl usually does not show any development within the test period.
(iv) Root system: A long primary root with secondary roots usually developing within the test period.
(2) Abnormal seedling description.
(i) Cotyledons:
(A) Less than half of the original cotyledon tissue remaining attached.
(B) Less than half of the original cotyledon tissue free of necrosis or decay. (Remove any attached seed coats at the end of the test period for evaluation of cotyledons.)
(ii) Epicotyl:
(A) Missing. (May be assumed to be present if cotyledons are intact.)
(B) [Reserved]
(iii) Hypocotyl:
(A) Deep open cracks extending into the conducting tissue.
(B) Malformed, such as markedly shortened, curled, or thickened.
(C) Watery.
(iv) Root:
(A) None.
(B) Weak, stubby, or missing primary root with weak secondary or adventitious roots. (Seedlings with roots bound within tough seed coats should be left in the test until the final count to allow for development.)
(v) Seedling:
(A) One or more essential structures impaired as a result of decay from primary infection.
(B) Albino.
[59 FR 64500, Dec. 14, 1994]