Myriophyllum alterniflorum
Alternate-leaved water-milfoil

Key Characteristics

Slender aquatic forb of shallow lakes; stems submerged with delicate branches and foliage, the leaves small (4-12 mm), finely dissected and whorled on the stem; flowers and fruits borne in an emergent spike, the uppermost flowers in axils of alternate (not whorled) bracts.

Status and Rank

  • State Status: SC
  • State Rank: S2S3
  • Global Rank: G5


County NameNumber of OccurrencesYear Last Observed
Distribution map for Myriophyllum alterniflorum

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Alternate-leaved water-milfoil is found in soft water lakes in Upper Michigan, in particular in the St Mary's River channel and bays of Isle Royale.

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Quillwort, water lobelia, grass-leaved arrowhead, spiked water-milfoil, awlwort, chara (green alga), spatterdock), pondweed, and common bladderwort.


This species requires protection and maintenance of lake hydrology. It is likely also susceptible to pollution and other threats that modify and degrade water quality.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Sep 24, 2018]


Survey References

Technical References

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