Lemna minuscula Herter   =Lemna minima   Lemnaceae (Duckweed Family)   Cosmopolitan   Least Duckweed

                                        September Photo

Plant Characteristics: Floating perennial aquatics, fronds solitary or in 2's or 4's, oblong-elliptical, 1.5-4 mm. long, 1-1.5 mm. wide, 1 nerved or nerveless, with a row of papillae along nerve on upper surface, flat or slightly convex beneath; fls. 3, rare, borne in the flowering pouch, 2 male, each of 1 stamen, and 1 female consisting of a single naked pistil; ovary 1-celled, 1-several ovuled; fr. ribbed; roots solitary on each plant.

Habitat: Occasional but well distributed, pools below 5000 ft.; several Plant Communities; San Diego Co. to desert edge in San Bernardino Co., no. to Trinity Co.; to Ore., Rocky Mts., e. U.S.  No bloom dates given in Munz.

Name:  Possibly Greek, limnos, lake, referring to living in swamps.  (Munz, Flora So. Calif. 918.  Latin, minimus, least, smallest and Latin, minusculus, very small. (Jaeger 156).

General:  Common in the freshwater ditch along Back Bay Dr. from Big Canyon northerly to the end of the road.   Photographed there.  (my comments).     Fred Roberts says that this is the only species of Lemna he has seen in the county and bases his identification mostly on lack of other species being found here.  Since that comment in about 1988, Roberts has listed L. minor, L. triuscula and L. valdiviana in his second edition of A Checklist of the Vascular Plants of Orange County, California. 1998.    Duckweed is a free floating, stemless aquatic plant with uses in waste management, animal feed and pharmaceuticals.  Duckweed is believed to be on of the world’s smallest flowering plants and one of the fastest growing.  It grows 20 times faster than corn, doubling in size within a few days through a natural cloning method.  Plants from the genus Wolfia and Lemna are both used to cleanse wastewater.  The plants reduce nitrogen and phosphorus in human waste and reduce the amount of fecal coliform by as much as 75%.  Duckweed also produces more protein on the average than soybeans and can be used to feed exotic fish.  Research is under way to genetically engineer duckweed to produce proteins like insulin. Currently the City of Snow Hill, NC, is using duckweed to treat hog waste.  Duckweed is grown in greenhouses 100 feet by 15 feet and untreated waste is pumped into the greenhouses where the duckweed feeds off the nutrients.  Workers harvest duckweed daily and take it to a drying area where it is later sold to feed operators for livestock. (Robertson, Gary D.  “Town in North Carolina Wants Weed to Treat Waste” Associated Press story in the Los Angeles Times 8 April, 2000: A22.    About 4 genera and 30 species.  (Munz, Flora So. Calif. 918.

Text Ref:  Hickman, Ed. 1169; Mason 334; Munz, Flora So. Calif. 918; Roberts 44.

Photo Ref:  Aug-Sept 87 # 20,21.

Identity: by R. De Ruff, confirmed by F. Roberts.

Computer Ref:  Plant Data 324.

Have plant specimen.

Last edit 2/15/03.

                               September Photo