| Author | (Michaux) Zardini | |
| Distribution | Weakley (2024) now has this species/taxon sunken into L. hexapetala. See that species account for the description of the former L. grandiflora.
Coastal Plain and lower Piedmont. Based on digital images, we cannot verify that all counties mapped are based on correctly identified specimens; for example Greenfield Lake in New Hanover County supposedly supports both L. grandiflora and L. hexapetala.
Native of South America (probably); in N.A. southern NY to FL and TX and MO; CA-OR-WA. | |
| Abundance | Rare to locally uncommon; easily confused with L. hexapetala, and some records of these two may be unsettled as to identity. | |
| Habitat | Lake shores, marshes, roadside ditches, railroad ditches, canals. | |
| Phenology | Flowering and fruiting May-September. | |
| Identification | This is one of the large-flowered water-primrose species. It is notable for the densely hirsute stems and branches. The leaves are variable, but generally are wider than those of L. bonariensis. To tell from its close relative L. hexapetala, see the key in Weakley (2018); however, L. grandiflora generally has smaller flowers -- about 1.5 inches across versus 2-2.5 inches across -- and leaves that are widest below the middle or at the middle versus widest toward the tip -- generally elliptical in shape as opposed to obovate (with a rounded tip in that species). | |
| Taxonomic Comments | Synonyms include L. grandiflora var. grandiflora and ssp. grandiflora, and L. uruguayensis in part. In 2024, Weakley subsumed this taxon within L. hexapetala.
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| Other Common Name(s) | | |
| State Rank | SYN | |
| Global Rank | GU | |
| State Status | | |
| US Status | | |
| USACE-agcp | OBL link |
| USACE-emp | OBL link |
