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Ceratophyllum demersum

L. (1753)

This name is accepted

Kingdom: Viridiplantae Phylum: Magnoliophyta Class/Clade: Ceratophyllopsida Order: Ceratophyllales Family: Ceratophyllaceae Genus: Ceratophyllum

coonstail, coontail, hornwort, rigid hornwort

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Description

Key Characters:

Growth Form: Plants entirely submerged, aquatic, rootless perennial herbs, without secondary growth.

Stems: Stems brittle or cordlike and flexuous, 0.5–3 m long, branched, forming large masses.

Roots:

Leaves: Leaves simple (highly dissected). Leaves in whorls of 3–12 per node. Blades dichotomously dissected, variable in length, often 1–2 cm long, ultimate divisions linear. Base sessile. Surfaces glabrous. Margins serrulate. Petioles absent. Stipules absent.

Flowers: Flowers minute and inconspicuous, axillary, staminate and pistillate flowers usually solitary at different nodes, often the staminate flowers above the pistillate ones. Flowers unisexual (and the plants monoecious); Hydrogamous (pollination under water). Calyx of 8–15 linear, bract-like segments, connate at base. Corolla (petals) absent. Stamens (5–)10–20(–27), distinct, spirally arranged on the flat receptacle, not clearly differentiated into filament and anther. Ovary superior, consisting of a single carpel tapering into the style; ovule 1, pendulous, orthotropous; styles 4–6 mm long; stigma decurrent.

Fruit: Achenes ellipsoid; compressed; 4–6 mm long; wingless; with 2 basal spines 2–5 mm long. seed with thin testa; endosperm absent. Seeds with thin seed coat; endosperm absent.

Ploidy: 2n = 24; 28; 38; 48

Habitat: Naturalized in ponds and reservoirs at least on Maui and Hawai'i.

Elevation Range:

Historical Distribution

Images

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Uses and Culture

USES

Natural History

Statewide Status

Naturalized

Island Status

Kaua'i Only found in cultivation
O'ahu Naturalized
Maui Naturalized
Hawai'i Naturalized

Dispersal Agents

Water/Ocean
Birds
Other Animals

Vegetative Reproduction

Pollinators

Notes

  • Description digitized by Mercedez
  • Description digitized from the Manual of the Flowering Plants of Hawaii
  • We have seen only a few naturalized collections from Kanahd Pond, Kahului, Maui, and Hilo and Waipi'o Valley, Hawai'i. Further collections are needed to determine island distribution.

Bibliography

Name Published In: Sp. Pl.: 992 (1753)

Other References

Wagner et al. 1990:533 (M, H); Staples et al. 2002:7 (O); Oppenheimer & Bartlett 2002:5 (WM); Staples & Herbst 2005:233 (DESCR)

Occurrences

SNo. Scientific Name Locality Habitat Basis of Record Recorded By Record Number Island Source Date
1 Ceratophyllum demersum Wailoa estuary, Hilo submerged aquatic Preserved_Specimen Stemmermann, R.L. 7181 Hawaii BISH 1981-07-25
2 Ceratophyllum demersum Richardson's outdoor recreation center, Hilo pond Preserved_Specimen Stemmermann, R.L. 7173 Hawaii BISH 1987-07-18
3 Ceratophyllum demersum Makawao, disturbed roadside on highway side of Kanaha Pond (Haleakala Hwy.) dominated by grasses, Pluchea indica and P. symphytifolia. Floating in canal adjacent to pond on SW corner Preserved_Specimen Wagner, W.L. 5803 Maui BISH 1988-03-03
4 Ceratophyllum demersum Honolulu, Bishop Museum glass aquarium Preserved_Specimen Ho, A. Oahu BISH 1934-09-06
5 Ceratophyllum demersum Kahului, canal SW corner Kanaha Pond floating, +/- submerged Preserved_Specimen Stemmermann, R.L. 7020 Maui BISH 1985-07-18
6 Ceratophyllum demersum W Maui, Lahaina District, Ukumehame Submerged in stagnant flood control channel w. Nymphaea & Eichhornia. Preserved_Specimen Oppenheimer, H.L. 30137 Maui BISH 2001-03-26
7 Ceratophyllum demersum W Maui, Lahaina District, Hanakaoo, Kaanapali Resort Submerged, forming dense mats at the south end of lagoon. Preserved_Specimen Oppenheimer, H.L. 109906 Maui BISH 1999-10-14
8 Ceratophyllum demersum Honolulu District, Salt Lake periphery channel Preserved_Specimen Funk, E.J. Oahu BISH 2000-10-03
9 Ceratophyllum demersum Waipio Valley wetland, abandoned taro patch with Myriophyllum, Egeria, Papyrus, taro, etc. Preserved_Specimen Stemmermann, R.L. 7141 Hawaii BISH 1987-05-17
10 Ceratophyllum demersum Shipman's pond, Keeau Preserved_Specimen Kay, A. 31763 Hawaii BISH
11 Ceratophyllum demersum Kailua, Coconut Grove area, 209 Oneawa Kai Place Preserved_Specimen Staples, G.W. 913 Oahu BISH 1994-02-24
12 Ceratophyllum demersum In drainage ditch adjacent to Kanaha Pond Preserved_Specimen Kobayashi, S. Maui BISH 1992-01-02
13 Ceratophyllum demersum Lihue District. Adams Residence Cultivated water garden, potted Undet. Hydrocharitaceae Preserved_Specimen Adams, J. 43 Kauai BISH 2014-01-01
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