| Author | (Walter) Britton, Sterns, & Poggenburg | |
| Distribution | Outer Coastal Plain and Outer Banks. The gap from Tyrrell and Dare counties down to New Hanover and Brunswick counties apparently is real.
Southeastern MA to SD, south to GA and TX. | |
| Abundance | Apparently rare. There needs to be a review of which populations are current and which historical, as VA has records from many southeastern counties, with the Digital Atlas of the Virginia Flora website giving its abundance there as "Infrequent" as opposed to rare. There are NC collections from 4 northeastern counties, so it may be extant from this area and perhaps not be truly rare; however, the specimens from this region are from deceased collectors. One Website Editor (Sorrie) failed to find it in surveys of the Outer Banks in 2012-13, which lends credence to the thought that M. pinnatum is rare and declining in NC. The NCNHP database does not have the complete set of records in its database, though it considers a record from Brunswick County as extant. The website editors prefer a State Rank of S1? rather than simply S1 as assigned by the NCNHP; it is a Significantly Rare species. | |
| Habitat | Natural ponds, interdune ponds, pools, ditches. |
| Phenology | Flowering and fruiting late March-October. | |
| Identification | Cutleaf Water-milfoil has dull red to brown stems that grow just beneath the water surface; they are not as thick or robust as stems of M. heterophyllum. The floral bracts grow in whorls of 4 and are cut into sharp segments (vs. broad and uncut in the latter species). Beware stranded plants of the latter; they produce narrow, sharp segments that closely resemble Cutleaf Water-milfoil. Loose Water-milfoil (M. laxum) has very short floral bracts which are generally hidden by flowers and fruits (vs. long and easily seen in Cutleaf Water-milfoil). Identification of all NC occurrences should be double-checked. | |
| Taxonomic Comments | None
| |
| Other Common Name(s) | Alternate-leaf Water-milfoil, Green Foxtail | |
| State Rank | S1 [S1?] | |
| Global Rank | G5 | |
| State Status | SR-T | |
| US Status | | |
| USACE-agcp | OBL link |
| USACE-emp | OBL link |
