The seed unit is the structure usually regarded as a seed in planting practices and in commercial channels. The seed unit may consist of one or more of the following structures:

True seeds;

For the grass family:

Caryopses and single florets;

Multiple florets and spikelets in tall oatgrass (Arrhenatherum elatius), oat (Avena spp.), gramas (Bouteloua spp.), rhodesgrass (Chloris gayana), barley (Hordeum vulgare), and bluegrass (Poa spp.);

Entire spikelets in bahiagrass, bentgrasses, dallisgrass, guineagrass, browntop millet, foxtail millet, proso millet, panicgrasses, redtop, rice, switchgrass, and vaseygrass. Entire spikelets which may have attached rachis segments, pedicels, and sterile spikelets in big bluestem, little bluestem, sand bluestem, yellow bluestem, bottlebrush-squirreltail, broomcorn, yellow indiangrass, johnsongrass, sorghum, sorghum- sudangrass, sorghum almum, sorgrass, and sudangrass;

Spikelet groups:

Spikelet groups that disarticulate as a unit in galletagrass;

Spikelet groups that disarticulate as units with attached rachis and internodes in bluestems, side-oats grama, and yellow indiangrass;

Fascicles of buffelgrass (Cenchrus ciliaris) consisting of bristles and spikelets;

Burs of buffalograss (Buchloe dactyloides);

Bulblets of bulbous bluegrass (Poa bulbosa);

Multiple units as defined in § 201.51a(b)(1).

Dry indehiscent fruits in the following plant families: Buckwheat (Polygonaceae), sunflower (Compositae), geranium (Geraniaceae), goosefoot (Chenopodiaceae), and valerian (Valerianaceae);

One- and two-seeded pods of small-seeded legumes (Leguminosae), burs of the burclovers (Medicago arabica, M. polymorpha), and pods of peanuts (Arachis hypogaea). (This does not preclude the shelling of small-seeded legumes for purposes of identification.) Pods of legumes normally containing more than two seeds, when occurring incidentally in the working sample, should be hulled if the kind is hulled when marketed;

Fruits or half fruits in the carrot family (Umbelliferae);

Nutlets in the following plant families: Borage (Boraginaceae), mint (Labiatae), and vervain (Verbenaceae);

“Seed balls” or portions thereof in multigerm beets, and fruits with accessory structures such as occur in other Chenopodiaceae and New Zealand spinach. For forage kochia refer to § 201.48(j) and § 201.51(a)(7).