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Ceratophyllum echinatum

(Prickly Hornwort)


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Common Names

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Click on the language to view common names.

Common Names in English:

Prickly Hornwort, Hornwort, prickly coontail, Spineless Hornwort, spiny hornwort, spring hornwort

Common Names in French:

Cornifle échinée, cornifle échinée

Common Names in unspecified:

Spineless Hornwort


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Family Ceratophyllaceae

Herbs perennial , submersed , hydrophilous, monoecious. Roots absent. Stems glabrous , branched, free or attached by slender shoots . Stipules absent. Leaves cauline, 3--11 in a whorl; petiole inconspicuous; leaf blade divided dichotomously into filiform segments; segments with 2 rows of denticles . Inflorescences reduced, solitary or with vestigial branches, 1-several at a node, extra-axillary , alternating with leaves, sessile or peduncles lengthening in fruit; involucre of 8--15 foliaceous bracts; bracts 1.5--2 mm, apex terminated by 2 denticles and a medial multicellular appendage . Flowers naked, subsessile . Staminate flower : stamens 3--50, spiral ; filaments short; anthers 2-celled, dehiscing by longitudinal slits. Pistillate flower: pistil 1, simple ; ovary 1-loculed, placentation laminar ; ovule 1, pendulous; style persistent , short or elongate ; stigma decurrent. Achene leathery, indehiscent, ellipsoid , smooth or tuberculate , basal spines 0--2, facial spines 0--2, marginal wing present or absent, marginal spines 1--8. Seed 1, unitegmic , endosperm and perisperm absent; cotyledons fleshy .

One genus and six species: cosmopolitan ; three species in China.[1]

Genus Ceratophyllum

Plants , submersed perennials . Stems suspended or anchored by branches buried in substrate; branches 0-3 per node. Leaves 3-11 per whorl, cauline; petiole inconspicuous. Leaf blade simple or forked into linear-filiform, denticulate segments. Inflorescences extra-axillary , alternating with leaves. Flowers: bracts basally connate , foliaceous ; pedicel less than 1 mm or essentially absent. Staminate flowers : anther 2-locular, connective projecting as apical appendage . Pistillate flowers: ovary tapering to persistent , spinelike style; ovule pendulous. Achene ellipsoid , moderately compressed , surface smooth or tuberculate , basal or marginal spines (or both) present or absent, terminal spine present, marginal wing present or absent. x = 12, 19, 20.

Useful in identification of species of Ceratophyllum are leaf-forking characteristics. Leaves with no forking are "0-order"; they consist only of a primary segment. Those forking once are "1st-order"; their ultimate segments are secondary. Those in which at least one secondary segment forks are "2d-order"; their ultimate segments are tertiary. Those in which at least one tertiary segment forks are "3d-order"; their ultimate segments are quaternary . Those in which at least one quaternary segment forks are "4th order ."

Plumule features used in the key below are observable through dissection of softened (soaked) seeds removed from achenes.[2]

Physical Description

Species Ceratophyllum echinatum

Stems to 1 m ; apical leaf whorls not densely crowded. Leaves dark green or olive-green, fine-textured. Leaf blade simple or forked into 2-10 ultimate segments (forking of largest leaves 3d or 4th order ), proximal segments often conspicuously inflated , mature leaf whorls 25-55 mm diam., marginal denticles weak and inconspicuous, weakly exserted, not raised on broad base of green tissue ; 1st leaves of plumule forked. Achene dark green or brown, body (excluding spines) 4.5-6 × 2.5-4.5 × 1.5-3 mm, basal spines 2 (rarely absent), straight or curved , 1-5 mm, marginal spines 2-13, 0.5-6.5 mm, terminal spine straight, 1.5-7.5 mm, margins winged . 2 n = 24. [source]

Principally an eastern North American species--and the only species of its genus endemic to North America-- Ceratophyllum echinatum is disjunct in the Pacific Northwest as a result of repeated Pleistocene glaciation. The habitats of C. echinatum are typically more acidic (avg. pH 6.6) than those of C. demersum (avg. pH 7.4). The two species only rarely coexist. Ceratophyllum echinatum also thrives in cooler, clearer, and more oligotrophic water than C. demersum and often is found in more ephemeral sites, such as shrub swamps (e.g. , with Cephalanthus occidentalis ) and beaver ponds . [source]

This species, relatively uncommon, is fast disappearing from much of its range because of habitat alteration or destruction and the introduction of nonindigenous species; steps should be taken to secure its conservation . Unlike Ceratophyllum demersum, C. echinatum does not attain status as a serious weed . [source]

Habit: Forb/herb

Flowers: Bloom Period: February, March, April, May, June, July.


Fresh water of lakes , ponds , marshes, swamps ; 0-500 m [3].

Typically found at an altitude of 0 to 719 meters (0 to 2,359 feet).[4]


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Duration: Perennial


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C. submersum Linnaeus var. echinatum (A. Gray) Wilmot-Dear • Ceratophyllum demersum echinatum (Gray) Gray • Ceratophyllum demersum L. var. echinatum (A. Gray) Wilmot-Dear • Ceratophyllum demersum L. var. echinatum (A.Gray) A.Gray • Ceratophyllum demersum Linnaeus var. echinatum (A. gray) A. Gray • Ceratophyllum demersum var. echinatum (Gray) Gray • Ceratophyllum submersum var. echinatum (Gray) Wilmot-Dear


Publishing author : A.Gray Publication : Ann. Lyceum Nat. Hist. New York 4(1): 49 1837 [Nov ? 1837]

Similar Species

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Members of the genus Ceratophyllum

ZipcodeZoo has pages for 6 species, subspecies, varieties, forms, and cultivars in this genus:

C. demersum (Common Hornwort) · C. echinatum (Prickly Hornwort) · C. muricatum (Prickly Hornwort) · C. muricatum australe (Prickly Hornwort) · C. muricatum subsp. australe (Prickly Hornwort) · C. submersum (Coontail)

More Info

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Further Reading

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Data Sources

Accessed through GBIF Data Portal November 21, 2007:



  1. Dezhi Fu & Donald H. Les "Ceratophyllaceae". in Flora of China Vol. 6 Page 121. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at [back]
  2. "Ceratophyllum". in Flora of North America Vol. 3. Oxford University Press. Online at [back]
  3. "Ceratophyllum echinatum". in Flora of North America Vol. 3. Oxford University Press. Online at [back]
  4. Mean = 202.720 meters (665.092 feet), Standard Deviation = 175.560 based on 369 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 2014-11-20