Justicia americana
Water willow
Image of Justicia americana

Photo by Bradford S. Slaughter 

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Key Characteristics

Mat-forming perennial of river slackwater areas; leaves opposite, narrowly elliptical; flowers pale violet marked with dark purple, borne in axillary clusters near top of plant.

Status and Rank

  • State Status: T
  • State Rank: S2
  • Global Rank: G5

Occurrences

County NameNumber of OccurrencesYear Last Observed
Barry11999
Livingston11939
Monroe51985
St. Joseph12006
Washtenaw32006
Wayne42002
Distribution map for Justicia americana

Updated 7/21/2017. 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.

Habitat

Mostly occurring in large river systems and less commonly in lakes. It is almost always found along muddy banks at the edge of the shore.

Natural Community Types

Methodology

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

Water-plantain, sedges, spike-rush, northern manna grass, cut grass, smartweed, arrowhead, bur-reed, cat-tail, wild rice, water-milfoil, watercress, great duckweed, water-lily, bulrush, pickerel weed, arrow-arum, and pondweed.

Management

Water-willow requires the protection of hydrology. Do not change the course of rivers or add impoundments. Agricultural run-off also likely has negative impacts.

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 http://mnfi.anr.msu.edu/explorer [Accessed Aug 23, 2017]

References

Survey References

Technical References

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