| Code | Definition | Number of Accessions |
| 10.2.4 | Chihuahuan Desert | 1 |
| 12.1.1 | Madrean Archipelago | 1 |
| 5.2.1 | Northern Lakes and Forests | 2 |
| 5.3.1 | Northern Appalachians and Atlantic Maritime Highlands | 3 |
| 5.3.3 | North Central Appalachians | 4 |
| 6.2.10 | Middle Rockies | 4 |
| 6.2.14 | Southern Rockies | 8 |
| 8.1.10 | Erie Drift Plain | 2 |
| 8.1.5 | Driftless Area | 4 |
| 8.1.6 | S. Michigan/N. Indiana Drift Plains | 3 |
| 8.1.7 | Northeastern Coastal Zone | 1 |
| 8.2.2 | Huron/Erie Lake Plains | 3 |
| 8.2.3 | Central Corn Belt Plains | 4 |
| 8.2.4 | Eastern Corn Belt Plains | 4 |
| 8.3.1 | Northern Appalachian Plateau and Uplands | 1 |
| 8.3.2 | Interior River Valley and Hills | 11 |
| 8.3.3 | Interior Plateau | 1 |
| 8.3.5 | Southeastern Plains | 1 |
| 8.3.7 | South Central Plains | 12 |
| 8.3.8 | East Central Texas Plains | 9 |
| 8.4.1 | Ridge and Valley | 9 |
| 8.4.2 | Central Appalachians | 3 |
| 8.4.3 | Western Allegheny Plateau | 4 |
| 8.4.4 | Blue Ridge | 5 |
| 8.4.5 | Ozark Highlands | 9 |
| 8.4.6 | Boston Mountains | 2 |
| 8.4.7 | Arkansas Valley | 2 |
| 8.4.8 | Ouachita Mountains | 1 |
| 8.4.9 | Southwestern Appalachians | 1 |
| 8.5.1 | Middle Atlantic Coastal Plain | 4 |
| 8.5.2 | Mississippi Alluvial Plain | 1 |
| 8.5.3 | Southern Coastal Plain | 1 |
| 9.2.3 | Western Corn Belt Plains | 20 |
| 9.2.4 | Central Irregular Plains | 4 |
| 9.3.1 | Northwestern Glaciated Plains | 2 |
| 9.3.4 | Nebraska Sand Hills | 4 |
| 9.4.1 | High Plains | 1 |
| 9.4.2 | Central Great Plains | 3 |
| 9.4.3 | Southwestern Tablelands | 3 |
| 9.4.4 | Flint Hills | 1 |
| 9.4.5 | Cross Timbers | 2 |
| 9.4.6 | Edwards Plateau | 2 |
| 9.4.7 | Texas Blackland Prairies | 2 |