1. (a) Unmixed seed. The working samples for purity analysis and noxiousweed seed examination of unmixed seed shall be at least the weights set forth in table 1.
2. (b) Mixtures consisting of one predominant kind of seed or groups of kinds of similar size. The weights of the purity and noxious-weed seed working samples in this category shall be determined by the kind or group of kinds which comprise more than 50 percent of the sample.
3. (c) Mixtures consisting of two or more kinds or groups of kinds of different sizes, none of which comprise over 50 percent of the sample. The weights of the purity working samples in this category shall be the weighted averages (to the nearest half gram) of the weights listed in table 1 for each of the kinds which comprise the sample determined by the following method: (1) Multiply the percentage of each component in the mixture (rounded off to the nearest whole number) by the sample sizes specified in column 2, table 1, (2) add all these products, (3) total the percentages of all components of the mixtures, and (4) divide the sum in paragraph (c)(2) of this section by the total in paragraph (c)(3) of this section. If the approximate percentage of the components of a mixture are not known they may be estimated. The weight of the noxious-weed seed working sample shall be determined by multiplying the weight of the purity working sample by 10 or by calculating the weighted average in the same manner described above for the purity working sample.

4. (d) Coated seed.

   1. (1) Unmixed coated seed. Due to variation in the weight of coating materials, the size or weight of the working sample shall be determined separately for each lot. The weight of the working sample shall be determined by weighing 100 completely coated units and calculating the weight of 2,500 coated units for the purity analysis and 25,000 coated units for the noxious-weed seed examination.

   2. (2) Mixtures of coated seed. The working weight shall be determined in the following manner:

      1. (i) Calculate the weight of the working sample to be used for the mixture under consideration as though the sample were not coated by following paragraph (b) or (c) of this section.

      2. (ii) Determine the amount of coating material on 100 coated units by weighing the coated units. Remove the coating material using the methods described in §§ 201.51b (c) and (d). Calculate the percentage of coating material using the following formulas:

         Weight of coating material = weight of 100 coated units − weight of 100 de-coated units; The percentage of coating material = weight of the coating material divided by the weight of 100 coated units × 100%.

      3. (iii) The weight of the working sample shall be the product of the weight calculated in paragraph (d)(2)(i) of this section multiplied by 100 percent, divided by 100 percent minus the percentage of coating material calculated in paragraph (d)(2)(ii) of this section.

         Table 1—Weight of Working Sample

         Name of seed	Minimum weight for purity analysis (grams)	Minimum weight for noxious-weed seed examination (grams)	Approximate number of seeds per gram
         Agricultural Seed
         Agrotricum	65	500	39
         Alfalfa	5	50	500
         Alfilaria	5	50	440
         Alyceclover	5	50	665
         Bahiagrass:
         Var. Pensacola	5	50	600
         All other vars.	7	50	365
         Barley	100	500	30
         Barrelclover	10	100	250
         Bean:
         Adzuki	200	500	11
         Field	500	500	4
         Mung	100	500	24
         Beet, field	50	500	55
         Beet, sugar	50	500	55
         Beggarweed, Florida	5	50	440
         Bentgrass:
         Colonial	0.25	2.5	13,000
         Creeping	0.25	2.5	13,515
         Velvet	0.25	2.5	18,180
         Bermudagrass	1	10	3,930
         Bermudagrass, giant	1	10	2,950
         Bluegrass:
         Annual	1	10	2,635
         Bulbous	4	40	585
         Canada	0.5	5	5,050
         Glaucantha	1	10
         Kentucky	1	10	3,060
         Nevada	1	10	2,305
         Rough	0.5	5	4,610
         Texas	1	10	2,500
         Wood	0.5	5	4,330
         Bluejoint	0.5	5	8,461
         Bluestem:
         Big	7	70	320
         Little	5	50	525
         Sand	10	100	215
         Yellow	1	10	1,945
         Bottlebrush-squirreltail	9	90	300
         Brome:
         Field	5	50	465
         Meadow	13	130	190
         Mountain	20	200	140
         Smooth	7	70	315
         Broomcorn	40	400	60
         Buckwheat	50	500	45
         Buffalograss:
         (Burs)	20	200	110
         (Caryopses)	3	30	740
         Buffelgrass:
         (Fascicles)	6	66	365
         (Caryopses)	2	20	1,940
         Burclover, California:
         (in bur)	50	500
         (out of bur)	7	70	375
         Burclover, spotted
         (in bur)	50	500	50
         (out of bur)	5	50	550
         Burnet, little	25	250	110
         Buttonclover	7	70	365
         Camelina	4	40	880
         Canarygrass	20	200	150
         Canarygrass, reed	2	20	1,185
         Carpetgrass	1	10	2,230
         Castorbean	500	500	5
         Chess, soft	5	50	555
         Chickpea	500	500	2
         Clover:
         Alsike	2	20	1,500
         Arrowleaf	4	40	705
         Berseem	5	50	455
         Cluster	1	10	2,925
         Crimson	10	100	330
         Kenya	2	20
         Ladino	2	20	1,935
         Lappa	2	20	1,500
         Large hop	1	10	5,435
         Persian	2	20	1,415
         Red	5	50	600
         Rose	7	70	360
         Small hop	2	20	1,950
         Strawberry	5	50	635
         Sub	25	250	120
         White	2	20	1,500
         Corn:
         Field	500	500	3
         Pop	500	500	3
         Cotton	300	500	8
         Cowpea	300	500	8
         Crambe	25	250
         Crested dogtail	2	20	1,900
         Crotalaria:
         Lance	7	70	375
         Showy	25	250	80
         Slenderleaf	10	100	205
         Striped	10	100	215
         Sunn	75	500	35
         Crownvetch	10	100	305
         Dallisgrass	4	40	620
         Dichondra	5	50	470
         Dropseed, sand	0.25	2.5	12,345
         Emmer	100	500	25
         Fescue:
         Chewings	3	30	900
         Hair	1	10
         Hard	2	20	1,305
         Meadow	5	50	495
         Red	3	30	900
         Sheep	2	20	1,165
         Tall	5	50	455
         Flatpea	100	500	25
         Flax	15	150	180
         Foxtail, creeping	1.5	15	1,736
         Foxtail, meadow	3	30	893
         Galletagrass:
         (Other than caryopses)	10	100	260
         (Caryopses)	5	50	580
         Grama:
         Blue	2	20	1,595
         Side-oats:
         (Other than caryopses)	6	60	350
         (Caryopses)	2	20	1,605
         Guar	75	500	35
         Guineagrass	2	20	2,205
         Hardinggrass	3	30	750
         Hemp	50	500	45
         Indiangrass, yellow	7	70	395
         Indigo, hairy	7	70	435
         Japanese lawngrass	2	20	1,325
         Johnsongrass	10	100	265
         Kenaf	50	500
         Kochia, forage	2	20	1,070
         Kudzu	25	250	80
         Lentil	120	500	14-23
         Lespedeza:
         Korean	5	50	525
         Sericea	3	30	820
         Siberian	3	30	820
         Striate	5	50	750
         Lovegrass, sand	1	10	3,585
         Lovegrass, weeping	1	10	3,270
         Lupine:
         Blue	500	500	7
         White	500	500	7
         Yellow	300	500	9
         Manilagrass	2	20
         Medic, black	5	50	585
         Milkvetch	9	90	270
         Millet:
         Browntop	8	80	315
         Foxtail	5	50	480
         Japanese	9	90	315
         Pearl	15	150	180
         Proso	15	150	185
         Molassesgrass	0.5	5	7,750
         Mustard:
         Black	2	20	1,255
         India	5	50	625
         White	15	150	160
         Napiergrass	5	50
         Needlegrass, green	7	70	370
         Oat	75	500	35-50
         Oatgrass, tall	6	60	417
         Orchardgrass	3	30	945
         Panicgrass, blue	2	20	1,370
         Panicgrass, green	2	20	1,305
         Pea, field	500	500	4
         Peanut	500	500	1-3
         Radish	30	300	75
         Rape:
         Annual	7	70	345
         Bird	7	70	425
         Turnip	5	50	535
         Winter	10	100	230
         Redtop	0.25	2.5	10,695
         Rescuegrass	20	200	115
         Rhodesgrass	1	10	4,725
         Rice	50	500	65
         Ricegrass, Indian	7	70	355
         Roughpea	75	500	40
         Rye	75	500	40
         Rye, mountain	28	280	90
         Ryegrass:
         Annual	5	50	420
         Intermediate	8	80	338
         Perennial	5	50	530
         Wimmera	5	50
         Safflower	100	500	30
         Sagewort, Louisiana	0.5	5	8,900
         Sainfoin	50	500	50
         Saltbush, fourwing	15	150	165
         Sesame	7	70	360
         Sesbania	25	250	105
         Smilo	2	20	2,010
         Sorghum	50	500	55
         Sorghum almum	15	150	150
         Sorghum-sudangrass	65	500	38
         Sorgrass 1	15	150	135
         Sourclover	5	50	660
         Soybean	500	500	6-13
         Spelt	100	500	25
         Sudangrass	25	250	100
         Sunflower	100	500
         Sweetclover:
         White	5	50	570
         Yellow	5	50	570
         Sweet vernalgrass	2	20	1,600
         Sweetvetch, northern	19	190	130
         Switchgrass	4	40	570
         Teff	1	10	3,288
         Timothy	1	10	2,565
         Timothy, turf	1	10	2,565
         Tobacco	0.5	5	15,625
         Trefoil:
         Big	2	20	1,945
         Birdsfoot	3	30	815
         Triticale	100	500
         Vaseygrass	3	30	970
         Veldtgrass	4	40	655
         Velvetbean	500	500	2
         Velvetgrass	1	10	3,360
         Vetch:
         Common	150	500	19
         Hairy	75	500	35
         Hungarian	100	500	24
         Monantha	100	500
         Narrowleaf	50	500	60
         Purple	100	500	22
         Woollypod	100	500	25
         Wheat:
         Common	100	500	25
         Club	100	500	25
         Durum	100	500	25
         Polish	100	500	25
         Poulard	100	500	25
         Wheat × Agrotricum	65	500	38
         Wheatgrass:
         Beardless	8	80	275
         Fairway crested	4	40	685
         Standard crested	5	50	425
         Intermediate	15	150	175
         Pubescent	15	150	180
         Siberian	5	50
         Slender	7	70	295
         Streambank	10	50	370
         Tall	15	150	165
         Western	10	100	250
         Wildrye:
         Basin	8	80	317
         Canada	11	110	190
         Russian	6	60	360
         Vegetable Seed
         Artichoke	100	500	24
         Asparagus	100	500	25
         Asparagusbean	300	500	8
         Bean:
         Garden	500	500	4
         Lima	500	500	2
         Runner	500	500	1
         Beet	50	300	60
         Broadbean	500	500
         Broccoli	10	50	315
         Brussels sprouts	10	50	315
         Burdock, great	15	150
         Cabbage	10	50	315
         Cabbage, Chinese	5	50	635
         Cabbage, tronchuda	10	100
         Cardoon	100	500
         Carrot	3	50	825
         Cauliflower	10	50	315
         Celeriac	1	25	2,520
         Celery	1	25	2,520
         Chard, Swiss	50	300	60
         Chicory	3	50	940
         Chives	5	50
         Citron	200	500	11
         Collards	10	50	315
         Corn, sweet	500	500
         Cornsalad:
         Vars. Fullhearted and Dark Green Fullhearted	5	50
         All other vars	10	50	380
         Cowpea	300	500	8
         Cress:
         Garden	5	50	425
         Upland	2	35	1,160
         Water	1	25	5,170
         Cucumber	75	500	40
         Dandelion	2	35	1,240
         Dill	3	50	800
         Eggplant	10	50	230
         Endive	3	50	940
         Gherkin, West India	16	160	153
         Kale	10	50	315
         Kale, Chinese	10	50
         Kale, Siberian	8	80	325
         Kohlrabi	10	50	315
         Leek	7	50	395
         Lettuce	3	50	890
         Melon	50	500	45
         Mustard, India	5	50	625
         Mustard, spinach	5	50	535
         Okra	100	500	19
         Onion	7	50	340
         Onion, Welsh	10	50
         Pak-choi	5	50	635
         Parsley	5	50	650
         Parsnip	5	50	430
         Pea	500	500	3
         Pepper	15	150	165
         Pumpkin	500	500	5
         Radish	30	300	75
         Rhubarb	50	300	60
         Rutabaga	5	50	430
         Sage	25	150	120
         Salsify	50	300	65
         Savory, summer	2	35	1,750
         Sorrel	2	35	1,080
         Soybean	500	500	6-13
         Spinach	25	150	100
         Spinach, New Zealand	200	500	13
         Squash	200	500	14
         Tomato	5	50	405
         Tomato, husk	2	35	1,240
         Turnip	5	50	535
         Watermelon	200	500	11
         1 Rhizomatous derivatives of a johnsongrass × sorghum cross or a johnsongrass × sudangrass cross.

[25 FR 8769, Sept. 13, 1960, as amended at 30 FR 7888, June 18, 1965; 32 FR 12780, Sept. 6, 1967; 35 FR 6108, Apr. 15, 1970; 41 FR 20156, May 17, 1976; 46 FR 53635, Oct. 29, 1981; 59 FR 64492, Dec. 14, 1994; 65 FR 1707, Jan. 11, 2000; 85 FR 40580, July 7, 2020]