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Elodea densa

(Planch.) Casp. (1857)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Monocots Order: Alismatales Family: Hydrocharitaceae Genus: Elodea

anacharis, ditch moss

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Description

Key Characters:

Growth Form: Aquatic herbs.

Stems: Stems terete (cylindrical), 2–3 mm in diameter.

Roots:

Leaves: Leaves simple. Leaves in whorls of 3. Blades ovate or narrowly ovate, 3–7 mm long, 1.5–2 mm wide, middle and upper leaves in whorls of 4–5, oblong to linear, 12–40 mm long, 1.7–5 mm wide. Margins serrulate. Sessile. Stipules absent.

Flowers: Flowers above water at anthesis, insect–pollinated, unisexual (and the plants dioecious). Sepals 3, green, smaller than petals, 3-4 mm long in male flowers. Petals 3, white, up to 9-12 mm long in male flowers. Staminate flowers borne in spathes in the upper leaf axils, 11–12 mm long, on a long thread-like hypanthium 30–60 mm long. Ovary likely inferior, pistillate flowers not seen.

Fruit: Unknown. Seeds without endosperm.

Ploidy: 2n = 2n =48

Habitat: Sparingly naturalized in ponds and perhaps also slow–running ditches.

Elevation Range:

Historical Distribution

Images

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Uses and Culture

USES

  • Yes

Natural History

Statewide Status

Naturalized

Island Status

Kaua'i Naturalized
O'ahu Naturalized
Molokai Not in flora
Maui Naturalized
Hawai'i Naturalized

Dispersal Agents


Pollinators

Bibliography

Name Published In: Monatsber. Königl. Preuss. Akad. Wiss. Berlin 1857: 49 (1857)

Other References

Wagner et al. 1990:1443 (K, O, Mo, H [as Egeria densa]); Oppenheimer 2003:14 (WM); Staples & Herbst 2005:666 (DESCR); Bernardini & Lucchese 2018/POWO 2025 (Syn. Egeria densa = Elodea densa); Faccenda, Arthur, et al. 2025:186 (remove Mo [no evidence of nat.])

Occurrences

SNo. Scientific Name Scientific Name Authorship Locality Habitat Basis of Record Recorded By Record Number Island Source Date
1 Elodea densa (Planch.) Casp. hilo, wailoa stream near kapiolani school PRESERVED_SPECIMEN kashiwamura, v. collector number: s.n. Oahu BISH 12/6/1993
2 Elodea densa (Planch.) Casp. Kailua, Kawainui Marsh, in slow-moving waterway on ranchlands of Martin Knott adjacent to ranch entrance PRESERVED_SPECIMEN Imada, C.T. 2000-7 Oahu BISH 6/8/2000
3 Elodea densa (Planch.) Casp. Hilo, Wailoa Stream near Kapiolani School Abundant supply. PRESERVED_SPECIMEN Kashiwamura, V. s.n. Hawaii BISH 12/6/1993
4 Elodea densa (Planch.) Casp. Cultivated in water pot, Keolu Hills, Kailua, Oahu, Hawaii Cultivated, Water pot, Kailua home. PRESERVED_SPECIMEN Crago, L.M. Collector Number: 2005-131 Oahu BISH 5/9/2005
5 Elodea densa (Planch.) Casp. honolulu PRESERVED_SPECIMEN hoe, w.j. (sub staples iii, g.w.) collector number: 564 Oahu BISH 3/6/1990
6 Elodea densa (Planch.) Casp. hilo PRESERVED_SPECIMEN ewart iii, g.r. collector number: s.n. Maui BISH 11/3/1937
7 Elodea densa (Planch.) Casp. Limahuli Valley. PTBG. PRESERVED_SPECIMEN Tim Flynn 793 Kauai PTBG 3/12/1984
8 Elodea densa (Planch.) Casp. Cultivated in water pot, Keolu Hills, Kailua, Oahu, Hawaii Cultivated, Water pot, Kailua home. PRESERVED_SPECIMEN Crago, L.M. 2005-131 Oahu BISH 5/9/2005
9 Elodea densa (Planch.) Casp. SE of Mt. Pohakupele, on N fork of Wailua River at irrigation ditch intake. Pool with mud bottom and steady flow of cool, clear water. PRESERVED_SPECIMEN David H. Lorence 7114 Kauai PTBG 11/4/1991
10 Elodea densa (Planch.) Casp. Blue Hole stream drainage. At end of Kuamoo road where cement crossing diverts stream into irrigation ditch. In still pool just makai of start of irrigation ditch. PRESERVED_SPECIMEN Clay Trauernicht 744 Kauai PTBG 2/12/2009
11 Elodea densa (Planch.) Casp. W. Maui, Olowalu, naturalized in reservoir. PRESERVED_SPECIMEN Hank Oppenheimer H110002 Maui PTBG 11/4/2000
12 Elodea densa (Planch.) Casp. Hanapepe River at Ho Road crossing, Hanapepe. PRESERVED_SPECIMEN David H. Lorence 5205 Kauai PTBG 5/5/1987
13 Elodea densa (Planch.) Casp. Aquarium plants cultivated in Singapore, shipped to Honolulu for Worldwide Aquatics, Waimanalo. Cultivated. PRESERVED_SPECIMEN William J. Hoe sub George Staples 564 Oahu PTBG 3/6/1990
14 Elodea densa (Planch.) Casp. Kaneohe Stream adjacent to Kaneohe Library. Fast-running fresh water stream. PRESERVED_SPECIMEN Clyde Hill 2001-27 Oahu PTBG 5/10/2001
15 Elodea densa (Planch.) Casp. blue hole stream drainage, at end of kuamoo road where cement crossing diverts stream into irrigation ditch, in still pool just makai of start of irrigation ditch. PRESERVED_SPECIMEN c. trauernicht & n. tangalin 744 Oahu US 2/12/2009
16 Elodea densa (Planch.) Casp. O'ahu. Kaneohe Stream PRESERVED_SPECIMEN C. Imada with R. Englund, D. Preston UNA 6/5/2001
17 Elodea densa (Planch.) Casp. Kawaihau District, southeast of Mt. Pohakupele, on north fork of Wailua River at irrigation ditch intake. PRESERVED_SPECIMEN Lorence, D. H.; Flynn, T. W. 7114 Kauai US 11/4/1991
18 Elodea densa (Planch.) Casp. Hawaii Volcanoes Nat Park PRESERVED_SPECIMEN Fosberg, F. R. 53709 Hawaii US 4/14/1971
19 Elodea densa (Planch.) Casp. napali coast, limahuli valley, just above mouth PRESERVED_SPECIMEN f. r. fosberg 64309 Kauai US 3/30/1984
20 Elodea densa (Planch.) Casp. Blue Hole stream drainage, at end of Kuamoo Road where cement crossing diverts stream into irrigation ditch, in still pool just makai of start of irrigation ditch. PRESERVED_SPECIMEN Trauernicht, C.; Tangalin, N. 744 Kauai US 2/12/2009
21 Elodea densa (Planch.) Casp. Kaneohe Stream adjacent to Kaneohe Library. In fast-running fresh water. PRESERVED_SPECIMEN Imada, C.; Preston, D. 2001-27 Oahu US 5/10/2001
22 Elodea densa (Planch.) Casp. Makiki Stream, in channelized section at intersection of Kalakaua Ave. and South King St. PRESERVED_SPECIMEN C. Imada 2001-54 Oahu US 8/19/2001
23 Elodea densa (Planch.) Casp. Napali Coast, Limahuli Valley, just above mouth PRESERVED_SPECIMEN Fosberg, F. R. 64309 Kauai US 3/30/1984
24 Elodea densa (Planch.) Casp. kawaihau district, southeast of mt. pohakupele, on north fork of wailua river at irrigation ditch intake. PRESERVED_SPECIMEN d. h. lorence & t. w. flynn 7114 Kauai US 11/4/1991
25 Elodea densa (Planch.) Casp. hawaii volcanoes nat park PRESERVED_SPECIMEN f. r. fosberg 53709 Hawaii US 4/14/1971
26 Elodea densa (Planch.) Casp. Makiki Stream, in channelized section at intersection of Kalakaua Ave. and South King St. PRESERVED_SPECIMEN Imada, C. 2001-54 Oahu US 2001-00-00
27 Elodea densa (Planch.) Casp. Kaneohe Stream adjacent to Kaneohe Library. In fast-running fresh water. PRESERVED_SPECIMEN C. Imada & D. Preston 2001-27 Oahu US 5/10/2001
28 Elodea densa (Planch.) Casp. kaneohe stream adjacent to kaneohe library. In fast-running fresh water. PRESERVED_SPECIMEN c. imada & d. preston 2001-27 Oahu US 5/10/2001
29 Elodea densa (Planch.) Casp. Blue Hole stream drainage, at end of Kuamoo Road where cement crossing diverts stream into irrigation ditch, in still pool just makai of start of irrigation ditch. PRESERVED_SPECIMEN C. Trauernicht & N. Tangalin 744 Kauai US 2/12/2009
30 Elodea densa (Planch.) Casp. Honolulu Distr., Makiki Stream, in channelized section at intersection of Kalakaua Ave. and South King St Associated with alien riparian vegetation, including Hydrilla, Amaranthus. PRESERVED_SPECIMEN Imada, C.T. Collector Number: 2001-54 Oahu BISH 8/19/2001
31 Elodea densa (Planch.) Casp. W Maui, Lahaina District, Olowalu In reservoir. PRESERVED_SPECIMEN Oppenheimer, H.L. H110002 Maui BISH 11/4/2000
32 Elodea densa (Planch.) Casp. Honolulu Cultivated in Aquaria. PRESERVED_SPECIMEN St.John, H. Collector Number: 11629 Oahu BISH 4/24/1932
33 Elodea densa (Planch.) Casp. kailua, kawainui marsh, in slow-moving waterway on ranchlands of martin knott adjacent to ranch entrance PRESERVED_SPECIMEN imada, c.t. roth, l. collector number: 2000-7 Oahu BISH 6/8/2000
34 Elodea densa (Planch.) Casp. koloa district, hanapepe river at ho rd crossing, hanapepe Rooting in 0.3-0.6 m water. PRESERVED_SPECIMEN lorence, d.h. flynn, t. collector number: 5205 Kauai BISH 5/5/1987
35 Elodea densa (Planch.) Casp. Hamakua District, Kukuihaele quad, Waipio Valley, area of Wailoa Stream nearest Naalapa Falls Common submerged aquatic herb in Wailoa Stream. PRESERVED_SPECIMEN Imada, C.T. 2001-19 Hawaii BISH 3/13/2001
36 Elodea densa (Planch.) Casp. Koloa District, Hanapepe River at Ho Rd crossing, Hanapepe Rooting in 0.3-0.6 m water. PRESERVED_SPECIMEN Lorence, D.H. 5205 Kauai BISH 5/5/1987
37 Elodea densa (Planch.) Casp. Pond below Kupelau Gulch PRESERVED_SPECIMEN Wilbur, R.L. 290 Oahu BISH 11/6/1947
38 Elodea densa (Planch.) Casp. Honolulu Cultivated in Aquaria. PRESERVED_SPECIMEN St. John, H. 11629 Oahu BISH 4/24/1932
39 Elodea densa (Planch.) Casp. Honolulu PRESERVED_SPECIMEN Hoe, W.J. 564 Oahu BISH 3/6/1990
40 Elodea densa (Planch.) Casp. kaneohe stream, in shallow, fast-running section of stream mossy rock, under trees PRESERVED_SPECIMEN imada, c.t. englund, r.; preston, d. collector number: 2001-43 Oahu BISH 6/5/2001
41 Elodea densa (Planch.) Casp. Kaneohe Stream adjacent to Kaneohe Library PRESERVED_SPECIMEN Imada, C.T. Preston, D. Collector Number: 2001-27 Oahu BISH 5/10/2001
42 Elodea densa (Planch.) Casp. hawaii volcanoes national park wet; ohia, Scaevola, moss PRESERVED_SPECIMEN fosberg, f.r. collector number: 53709 Kauai BISH 4/14/1971
43 Elodea densa (Planch.) Casp. Hamakua District, Kukuihaele quad, Waipio Valley, area of Wailoa Stream nearest Naalapa Falls Common submerged aquatic herb in Wailoa Stream. PRESERVED_SPECIMEN Imada, C.T. Puttock, C. Collector Number: 2001-19 Hawaii BISH 3/13/2001
44 Elodea densa (Planch.) Casp. kaneohe stream adjacent to kaneohe library PRESERVED_SPECIMEN imada, c.t. preston, d. collector number: 2001-27 Oahu BISH 5/10/2001
45 Elodea densa (Planch.) Casp. Kaneohe Stream adjacent to Kaneohe Library PRESERVED_SPECIMEN Imada, C.T. 2001-27 Oahu BISH 5/10/2001
46 Elodea densa (Planch.) Casp. hilo `A`a lava land. PRESERVED_SPECIMEN ewart iii, g.r. collector number: s.n. Hawaii BISH 11/3/1937
47 Elodea densa (Planch.) Casp. Hilo Choking pool. PRESERVED_SPECIMEN Ewart III, G.R. Collector Number: s.n. Hawaii BISH 11/3/1937
48 Elodea densa (Planch.) Casp. honolulu edge of crater PRESERVED_SPECIMEN st.john, h. collector number: 11629 Oahu BISH 4/24/1932
49 Elodea densa (Planch.) Casp. Honolulu PRESERVED_SPECIMEN Hoe, W.J. (sub Staples III, G.W.) Collector Number: 564 Oahu BISH 3/6/1990
50 Elodea densa (Planch.) Casp. Honolulu Distr., Makiki Stream, in channelized section at intersection of Kalakaua Ave. and South King St Associated with alien riparian vegetation, including Hydrilla, Amaranthus. PRESERVED_SPECIMEN Imada, C.T. 2001-54 Oahu BISH 8/19/2001
51 Elodea densa (Planch.) Casp. Blue Hole drainage, end of Kuamoo road still pool makai of start of irrigation ditch PRESERVED_SPECIMEN Trauernicht, C. 744 Kauai BISH 2/12/2009
52 Elodea densa (Planch.) Casp. w maui, lahaina district, olowalu PRESERVED_SPECIMEN oppenheimer, h.l. nelson, l.; duvall, f. collector number: h110002 Molokai BISH 11/4/2000
53 Elodea densa (Planch.) Casp. honolulu international airport; aquatic plants from singapore PRESERVED_SPECIMEN hoe, w.j. (sub staples iii, g.w.) collector number: 507 Oahu BISH 11/14/1989
54 Elodea densa (Planch.) Casp. Kailua, Kawainui Marsh, in slow-moving waterway on ranchlands of Martin Knott adjacent to ranch entrance PRESERVED_SPECIMEN Imada, C.T. Roth, L. Collector Number: 2000-7 Oahu BISH 6/8/2000
55 Elodea densa (Planch.) Casp. hamakua district, kukuihaele quad, waipio valley, area of wailoa stream nearest naalapa falls Common submerged aquatic herb in Wailoa Stream. PRESERVED_SPECIMEN imada, c.t. puttock, c. collector number: 2001-19 Hawaii BISH 3/13/2001
56 Elodea densa (Planch.) Casp. Blue Hole drainage, end of Kuamoo road still pool makai of start of irrigation ditch PRESERVED_SPECIMEN Trauernicht, C. Tangalin, N. Collector Number: 744 Kauai BISH 2/12/2009
57 Elodea densa (Planch.) Casp. makiki stream, in channelized section at intersection of kalakaua ave. and south king st. wet forest PRESERVED_SPECIMEN c. imada 2001-54 Oahu BISH 8/19/2001
58 Elodea densa (Planch.) Casp. Hilo Choking pool. PRESERVED_SPECIMEN Ewart III, G.R. s.n. Hawaii BISH 11/3/1937
59 Elodea densa (Planch.) Casp. W Maui, Lahaina District, Olowalu In reservoir. PRESERVED_SPECIMEN Oppenheimer, H.L. Nelson, L.; Duvall, F. Collector Number: H110002 Maui BISH 11/4/2000
60 Elodea densa (Planch.) Casp. Honolulu International Airport; aquatic plants from Singapore PRESERVED_SPECIMEN Hoe, W.J. 507 Oahu BISH 11/14/1989
61 Elodea densa (Planch.) Casp. blue hole drainage, end of kuamoo road moist woods PRESERVED_SPECIMEN trauernicht, c. tangalin, n. collector number: 744 Oahu BISH 2/12/2009
62 Elodea densa (Planch.) Casp. Hawaii Volcanoes National Park Abundant in fresh water pond back of dunes. PRESERVED_SPECIMEN Fosberg, F.R. 53709 Hawaii BISH 4/14/1971
63 Elodea densa (Planch.) Casp. honolulu distr., makiki stream, in channelized section at intersection of kalakaua ave. and south king st koa, ohia forest PRESERVED_SPECIMEN imada, c.t. collector number: 2001-54 Oahu BISH 8/19/2001
64 Elodea densa (Planch.) Casp. cultivated in water pot, keolu hills, kailua, oahu, hawaii Cultivated, Water pot, Kailua home. PRESERVED_SPECIMEN crago, l.m. collector number: 2005-131 Oahu BISH 5/9/2005
65 Elodea densa (Planch.) Casp. pond below kupelau gulch PRESERVED_SPECIMEN wilbur, r.l. collector number: 290 Oahu BISH 11/6/1947
66 Elodea densa (Planch.) Casp. Kaneohe Stream, in shallow, fast-running section of stream Forming thick mats underwater along with Vallisneria americana and an unidentified matted Alismataceae (Imada et al. 2001-44). PRESERVED_SPECIMEN Imada, C.T. Englund, R.; Preston, D. Collector Number: 2001-43 Oahu BISH 6/5/2001
67 Elodea densa (Planch.) Casp. Kaneohe Stream, in shallow, fast-running section of stream Forming thick mats underwater along with Vallisneria americana and an unidentified matted Alismataceae (Imada et al. 2001-44). PRESERVED_SPECIMEN Imada, C.T. 2001-43 Oahu BISH 6/5/2001
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