Flora of North America species comparison

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Ruppia cirrhosa

Ruppiaceae

ditch grass, spiral ditch-grass

ditch-grass family
Habit Herbs, annual or rarely perennial, not rhizomatous, caulescent; turions absent [present].
Stems

to 55 cm × 0.1–0.3 mm.

Leaves

3.2–45.1 cm;

blade 0.2–0.5 mm wide, apex acute.

alternate to subopposite, submersed, sessile;

sheath not persisting longer than blade, not leaving circular scar when shed, not ligulate, not auriculate;

blade linear;

intravaginal squamules scales, 2.
Inflorescences

peduncles with 5–30 coils, 30–300 × 0.5 mm.

terminal, capitate spikes, with subtending spathe, pedunculate;

peduncle following fertilization often elongating, often spiraling.
Flowers

pistils 4–6.

bisexual; subtending bracts absent;

perianth absent;

stamens 2, in 1 series;

anthers distinct, dehiscing longitudinally;

pollen arcuate;

pistils 4–16, distinct, stipitate;

ovules parietal, campylotropous.
Fruits

1.5–2 × 1.1–1.5 mm;

gynophore 2–3.5 cm;

beak lateral, erect, 0.5–1 mm.

drupaceous.
Seeds

1;

embryo straight.
2n

= 40 (Europe).

Ruppia cirrhosa

Ruppiaceae
Phenology Flowering summer–fall.
Habitat Shallow to deep fresh waters of lakes with high concentrations of sulfur or calcium
Elevation 300–2500 m (1000–8200 ft)
Distribution
from FNA
AK; AZ; CA; CO; IL; KS; MI; MN; MO; MT; ND; NE; NM; NV; OH; OK; OR; SD; TX; UT; WA; WY; AB; BC; MB; NT; SK; YT; Central America; South America; West Indies; Europe
[WildflowerSearch map]
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Nearly worldwide
[BONAP county map]
Discussion

Ruppia spiralis Linnaeus has occasionally been used for this taxon in North America. Linnaeus, however, had never published that name (J. T. A. Verhoeven 1979). Ruppia cirrhosa is, indeed, the correct name for the taxon (J. C. Gamerro 1968).

An implication that the North American material with long, spiraling peduncles is different from the European material of Ruppia cirrhosa stems from the statement that R. occidentalis occurs in inland lakes (J. T. A. Verhoeven 1979). No differences between European R. cirrhosa and the North American material are listed, however. In fact, a comparison of the Verhoeven's descriptive discussions for of R. cirrhosa (Verhoeven 1979) with the North American material shows that the two are the same. The genus should be studied on a worldwide basis. Until further studies indicate otherwise, I am considering North American and European material to be conspecific.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Ruppiaceae are found submersed in brackish or saline waters or fresh waters with very high calcium or sulfur ion concentrations.

Genus Genera 1, species ca. 10 (2 species in the flora).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 22. FNA vol. 22, p. 75. Author: Robert R. Haynes.
Parent taxa Ruppiaceae > Ruppia
Sibling taxa
R. maritima
Subordinate taxa
Synonyms Buccaferrea cirrhosa, R. cirrhosa subsp. occidentalis, R. occidentalis
Name authority (Petagna) Grande: Bull. Orto Bot. Regia Univ. Naapoli 5: 58. (1918) Horaninow ex Hutchinson
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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