Mexican Water Fern

As I was researching this odd plant, two obvious facts emerged: this is not a wildflower because it is a fern and ferns don't have flowers; and it is an aquatic fern, which I did not know existed. However, because the Mexican Water Fern (Azolla mexicana) is a common wetland plant in our area, but unique, I thought it deserves a post in the blog!

You may have seen area wetlands or large ponds covered with tiny green floating plants. These ferns are a darker green than algae and is top side only, unlike algae which can grow underwater as well. The tiny green leaves turn to a brownish red this time of year (10/17/2013), making more of a contrast in the water. Several of the ponds at Jackson Bottom are awash in this fern, where they seem to thrive.

Because they are ferns, reproduction is by spores. There are no flowers, fruits, or seeds. Blue-green algae in the leaves can absorb (fix) nitrogen from the air, something plants cannot do. This provides nutrients for the plant, while the plant provides shelter and minerals for the blue-green algae. Water-fern is used as green fertilizer in rice paddies because of its nitrogen fixing ability. It also provides food for waterfowl and cover for small invertebrates. Water-fern is considered a threatened species in British Columbia.

It can become a nuisance and choke out other aquatic plants in some environments. On the other hand, it is also cultivated and harvested in some areas for fertilizer, hence the nickname "green manure."

From a distance, this water looks brackish.
(Jackson Bottom Wetlands)

The wind blows these ferns to the edge of the water.

This clump is starting to go from green to brown.

The tiny leaves are just 3 - 5 mm wide.

In this detail, you can see the scale-like leaf parts.