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Contact information
For information on Wisconsin's rare plants, contact:
Kevin Doyle
608-416-3377

Floating-fern (Azolla mexicana)

Need a main photo for this plant


Life history

Species overview

Floating-fern (Azolla mexicana), a plant, is found in still to slow-moving water. The optimal identification period for this species is summer through fall.

Synonyms: Azolla cristata

Identification

  • Distinguishing characteristics: Most likely to be confused with Azolla caroliniana, which is generally a smaller plant (0.5 to 1 cm wide) with bigger leaves (0.5 mm long), and the glochidia do not have cross-walls.
  • Flower characteristics:
  • Fruit characteristics: A fern, the microspores are contained in massulae 0.2 to 0.3 mm wide. Each massula has a thin wall with glochidia that have cross-walls. The megaspores are 0.4 to 0.5 mm wide with pitted and rouned bases.
  • Leaf characteristics: Arranged in rows of 2, the tiny, scale-like leaves are 1 mm long and smooth. They have two lobes, the upper 0.7 to 0.9 mm wide and much smaller than the lower, submersed lobe. Can be pinnately branched, and the first leaf of a branch holds the sporocarp. Usually green, the leaves turn red by mid-summer.

Phenology

  • Blooming phenology:
  • Fruiting phenology:
  • Optimum time to identify: The optimal identification period for this species is summer through fall

Other

  • Growth form: Aquatic fern
  • Vegetative reproduction: Broken-off branches will form a new plant
  • Life cycle: Annual or short-lived perennial
  • Comments:

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

Floating-fern (Azolla mexicana) is on the "watch list." Watch list species have experienced, or are believed to have experienced, a statewide or range wide decline, but they are not currently tracked in the Natural Heritage Inventory (NHI) database. The watch list includes newly discovered species for which origin and rarity need to be determined, certain animals designated as Species of Greatest Conservation Need (SGCN) in the Wisconsin Wildlife Action Plan, and species that were tracked in the past but proved more abundant, widespread or less vulnerable than previously thought. Although watch list species are not actively tracked by NHI, occurrences documented during surveys are often stored by NHI, as these species could be tracked in the future if there is further evidence of their decline.


Summary Information
State Statusnone
Federal Status in Wisconsinnone
State RankSU
Global RankG5
Tracked by NHIW

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

  • Habitat description: Found in still to slow-moving water.
  • Soils:

Natural communities

This table lists the natural communities that are associated with Floating-fern. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Natural communities score

Ecological landscapes

This table lists the ecological landscape association scores for Floating-fern. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Map of the Ecological Landscapes of Wisconsin.

Ecological landscape score

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

  • No avoidance measures have been developed for this species.

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

  • No guidance has been developed for this species.

Photos

No additional photos are available for Floating-fern at this time. Please consider donating a photo to the Natural Heritage Conservation Program.


Support for Wisconsin's rare plant information has been provided by the Division of Forestry, the Endangered Resources Fund and the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].

Last revised: Friday, August 10, 2018
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