Aquatic, floating, dark-red (when exposed) or glaucous-green plants, forms ovate to ovoid patches on the surface of water bodies. Branching irregular; roots peg-like, simple: not branched. Leaves triangular; apex rounded; margins membranous, translucent; surface smooth, bright red or glaucous-green. Microsporangiate massulae spherical, surface conspicuously barbed. Megasporocarps brown, partially obscured by leaf lobe (NZPCN, 2013)
Common names include; Large mosquito fern, Red Water fern, Duckweed fern, Fairy moss
Not threatened in native sites, Native to western Australia and New Zealand, Name status: Current (Florabase, 2013)
Not threathened
Stems slender, branching, floating on water, individually or form dense monospecific thin mats (20cm thick) with hanging, simple roots up to 6cm long, without scales. Plants 1-2.5cm long, bipinnate, dark green/blue to bright red, small, not spirally coiled when young, fronds densely imbricate, 2-lobed leaves and rhizomes. Upper lobe floating, ovate, obtuse covered above in unicellular hair, non-soluble, margins hyaline. Lower lobe submerged, bears the sori in pairs on cylindrical receptacles, borne 1st leaf of each branch, heterosporous, indusium surrounding from base, consists of either numerous microsporangia developed successively from apex to base of sorus or a single megasporangium, called sporocarp (1.5mm), annulus 0. Each sporangium has 1 megaspore with 3 floats; massulae of 64 microsporangium, massula branching barbed hairs, not divided by transverse walls into cells, glochidia joins megaspore and massulae. Propagates both sexually and asexually. Spores are dispersed.
A. rubra differs from A. pinnata by pinnate rather than simple roots. Azolla pinnata is extremely invasive and has largely replaced A. rubra in Northland and Auckland (NZPCN, 2013)
Little information on the evolution of A. rubra
Class: Polypodiopsida
Order: Salviniales
Family: Salviniaceae
Martinov
Genus: Azolla Lam.
Species: Azolla rubra R. Br
Common within the South West province of Western Australia. IBRA Regions: Jarrah Forest, Swan Coastal Plain. IBRA Subregions: Dandaragan Plateau, Northern Jarrah Forest, Perth, Southern Jarrah Forest. The Local Government Areas (LGAs): Albany, Armadale, Canning, Cockburn, Dandaragan, Gingin, Harvey, Kalamunda, South Perth, Swan, Vincent. (Florabase, 2013)
A. rubra is an aquatic plant found in shallow water bodies such as ponds, lake margins, dams and slow flowing streams. Also present in swamps on muddy ground. Azolla is mostly common in shallow eutrophic water bodies but may be established in more acidic wetland systems, where it is often a conspicuous plant of the lagg zone. (NZPCN, 2013)
Nitrogen fixing, obligate symbiotic association with the cyanobacterium Anabaena azollae Strasburger, promotes use of Azolla as green manure for rice paddies in Southeast Asia. (Hussner, 2010)
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