| Kalmia latifolia | Mountain Laurel |
| Koelreuteria paniculata | Golden Rain-tree |
| Kosteletzkya pentacarpos var. pentacarpos | Sea-shore Mallow |
| Kosteletzkya virginica var. aquilonia | Sea-shore Mallow |
| Kosteletzkya virginica | Sea-shore Mallow |
| Krigia virginica | Virginia Dwarf-dandelion |
| Kummerowia stipulacea | Stipuled Korean-clover |