Azolla filiculoides Lam.

Azollaceae (Salviniaceae)

Mosquito Fern Family




Duckweed Fern 


Pacific Mosquito Fern    


                                    August Photo


Plant Characteristics:  Small mosslike plants with pinnately branched stems covered with minute imbricate 2-lobed lvs. producing rootlets beneath; often reddish, 1-2.5 cm. long, easily breaking apart; lvs. ovate, 1 mm. long, the dorsal lobe papillate-hairy, the ventral submersed and forming sporocarps; sporocarps of 2 kinds, borne in pairs beneath the stem, the small ones ovoid and bearing 1 macrospore, the larger globose and containing masses of microspores.


Habitat:  Frequent in sluggish water at low elevs., cismontane Calif., occasional on the deserts as on Mojave R.; to Wash., Ariz., S. Am.  Bloom data not given in Munz.       Not found in saline areas.  Found below 1600 m. (Hickman, Ed. 90).


Name:  Azolla, Greek name of doubtful origin.  (Munz, Flora So Calif. 34).  Greek, azo, to dry.  Ex. Azolla, azo+alloyo, to kill, since the plants are killed by drought. (Jaeger 32). Latin, filum, threadlike.  (Jaeger 102).  New Latin, oides, a contraction of Gr. o+eidos, denoting likeness of form, a thing that is like.  (Jaeger 172).  The species name may refer to the growth pattern of small branched stems.  (my comment).


General:  Common in the study area.   Photographed at 23rd Street.  (my comments).      All too often, the characters by which the species of Azolla are identified are not very satisfactory; in particular, size of plant, character of branching, overlapping of leaves, and number of microsporangia are so variable as not to be convincing criteria for identification.  The characters used in Mason's key, however, are reasonably stable.  The key shows two species, with differences being in whether microsporangic massulae are septate or nonseptate.  (Mason 31).      Six species in the genus.  (Munz, Flora So. Calif. 35).      The 1993 Jepson Manual changes the family name from Salviniaceae to Azollaceae.


Text Ref:  Abrams, Vol. I 35; Hickman, Ed. 90; Mason 34; Munz, Flora So. Calif. 34; Roberts 5.

Photo Ref:  Aug 1 86 # 20.

Computer Ref:  Plant Data 296.


Identity by F. Roberts.

Have plant specimen.

Last edit 6/29/00.