|
|
Practical ecological knowledge for the temperate reader. |
Family: Lemnaceae [IFBC-E-flora]
Key to the Species and Taxonomic Notes
Introduction
"Turion duckweed, or red duckweed, is a native species in North America that is found in eutrophic (basic) quiet waters. It is found across the continent but is not reported, so far, in southeastern US states or in parts of the Arctic (USDA Plants Database 2010). It was collected twice in BC in 1978 by John Pinder-Moss (Hatzic Slough near Mission) and since then has been collected from several locations (south of Fort Langley, Deer Lake in Burnaby, Chilliwack, Hatzic Slough, Silverdale, and Swan Lake in Victoria." [E-flora]
"Turion duckweed closely resembles common duckweed (Lemna minor). However, fronds are flat, more symmetrical, thinner, and are reddish coloured on the lower surface, unlike common duckweed. Additionally, Armstrong (2010) says L. turionifera has "a row of minute papules along the midline which are absent in L. minor". This is the only Lemna species that produces turions (overwintering buds). A detailed species description is provided in Flora North America. Additionally, Wayne Armstrong provides detailed taxonomic information for separating species in the Lemnaceae, as well as many good photos. Turion duckweed is now present and invasive in Europe." [E-flora]
"Lemna minor is a PERENNIAL. It is hardy to zone (UK) 4 and is not frost tender. It is in flower from June to July. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant). It is noted for attracting wildlife. Suitable pH: neutral and basic (alkaline) soils. It cannot grow in the shade. It can grow in water." [PFAF]
"General: Fronds annual, free-floating, usually in pairs, elliptic, rounded or broadly egg-shaped, 2-6 mm long, unstalked, quickly becoming detached, obscurely 3-nerved, the young plants produced from a pair of marginal pouches near the base of the frond." [IFBC-E-flora]
"Notes: The separation of L. turionifera from L. minor, based on characters which are usually absent in BC or are sometimes found in L. minor, is not practical in this flora. Lemna turionifera has dark green or brown winter buds and fronds which are 3- to 5-nerved and purple-red beneath." [IFBC-E-flora]
"Habitat / Range Ponds and slow-moving streams in the lowland, steppe and montane zones; common throughout BC south of 55degreeN, less frequent northward, absent in NW BC and rare in the Queen Charlotte Islands; circumpolar, N to AK, YT and NT, E to NF and S to FL, MS, TX, NM, AZ, CA and MX; Eurasia." [IFBC-E-flora] "Still water[17]. Mesotrophic to eutrophic, quiet waters, in suboceanic, cool-temperate regions with relatively mild winters[270]. A cosmopolitan plant, found in most regions of the world, including Britain, absent from Tropics." [PFAF]
Status: Native [E-flora]
Edible Uses
Other Uses
Medicinal Uses
Cultivation & Propagation
"Requires a sunny position in still water that is rich in nitrates and lime[200]. Duckweed can be a troublesome pond weed though it is easily controlled by simply scooping it out[56, 200]. This scooped out material makes an excellent addition to the compost heap. The growing plant is a good food source for fish and birds, as well as providing cover for creatures in the pond[200]. Although it is towards the limit of its climatic range in Britain, it often flowers here if growing in a sheltered sunny position[17]. It over-winters in temperate areas by means of resting buds which sink to the bottom of the pond in the late autumn and rise again in the spring[200]." [PFAF]
"Seed - we have no information on this species but, since it spreads so rapidly by division, it really needs no extra help once it is in a pond." [PFAF]
Synonyms
References
"Lemna trisulca is a PERENNIAL. It is hardy to zone (UK) 4 and is not frost tender. It is in flower from May to July. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant). It is noted for attracting wildlife. Suitable pH: neutral and basic (alkaline) soils. It cannot grow in the shade. It can grow in water." [PFAF]
"General: Fronds annual, usually submersed, oblong to lanceolate, 6-12 mm long, long-stalked, remaining attached in a zig-zag chain, obscurely 3-nerved, the young plants produced from pouches on either side near the junction of the stalk and the plant body." [IFBC-E-flora]
"Habitat / Range Ponds and slow-moving streams in the lowland, steppe and montane zones; frequent throughout BC south of 56degreeN, absent on the Queen Charlotte Islands and the mainland coast, infrequent elsewhere in BC east of the Coast-Cascade mountains and S of 55degreeN; circumpolar, N to AK, YT and NT, E to NB and NS and S to VA, AL, AR, TX, NM, AZ, CA and MX; Eurasia, S America." [IFBC-E-flora] "Ponds and ditches in all parts of Britain except north Devon and east Cornwall[17]. Mesotrophic, quiet waters rich in calcium, in cool-temperate regions[270]. Europe, including Britain, from Scandanavia south and east to N. Africa, Asia, N. America, Australia" [PFAF]
Status: Native [E-flora]
Medicinal Uses
Cultivation & Propagation
"Requires a sunny position in still water that is rich in nitrates and lime[200]. Duckweed can be a troublesome pond weed though it is easily controlled by simply scooping it out[56, 200]. This scooped out material makes an excellent addition to the compost heap. The growing plant is a good food source for fish and birds, as well as providing cover for creatures in the pond[200]. This species is very suitable for use in cold water aquaria though, like all members of the genus, it can harbour fish parasites[200]. The plant over-winters in temperate areas by means of resting buds which sink to the bottom of the pond in the late autumn and rise again in the spring[200]." [PFAF]
"Seed - we have no information on this species but, since it spreads so rapidly by division, it really needs no extra help once it is in a pond." [PFAF]
References