Flora of North America species comparison

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Callitriche stagnalis

Callitriche heterophylla

callitriche des eau× stagnantes, pond water-starwort

different-leaf water-starwort, diverse-leaf water-starwort, greater water-starwort, large water-starwort, prairie sandgrass, two-head water-starwort, variedleaf waterstarwort, water starwort
Stem

and leaf scales present.

and leaf scales present.
Leaves

connate at base, obovate-spatulate to ± round, 4–9 × 1–4 mm, 1+-veined.

connate at base, ± linear, tapering from near base or spatulate, 3.7–24.7 × 0.3–3.5 mm, 1+-veined.
Inflorescences

bracts persistent.

bracts caducous.
Pedicels

0–0.2 mm in fruit.

0 mm in fruit.
Flowers

solitary;

styles erect;

pollen yellow.

usually solitary;

styles erect or spreading;

pollen yellow.
Schizocarps

1.2–1.8 × 1–1.7 mm, ± as long as wide;

mericarps pale grayish brown, not swollen, winged throughout, wings straight, 0.1–0.5 mm wide.

± round, (0.4–)0.5–0.9(–1.2) × 0.5–1(–1.2) mm, as long as wide;

mericarps black, not swollen, not winged or winged only at apex, wings straight, 0.05–0.1 mm wide.
2n

= 10.

Callitriche stagnalis

Callitriche heterophylla
Phenology Flowering May–Oct. Flowering Feb–Nov.
Habitat Standing water, stream margins, backwaters, ponds, pools, ditches. Fast-flowing streams, backwaters, ditches, swamps, Sphagnum bogs, lakes, ponds, springs, seepages, seasonally damp soils in shade.
Elevation 0–1500 m. (0–4900 ft.) 0–3000 m. (0–9800 ft.)
Distribution
from FNA
AL; CA; CT; MA; MD; ME; MO; MT; NJ; NY; OR; PA; VA; WA; WI; BC; NF; QC; SPM; Europe [Introduced in North America; introduced also in Australia]
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; AL; AR; AZ; CA; CT; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MO; MS; MT; NC; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; TN; TX; VA; VT; WA; WI; AB; BC; MB; NB; NF; NS; ON; QC; YT; Mexico; Central America; South America; West Indies (Antilles); Greenland [Introduced in Pacific Islands (New Zealand)]
[WildflowerSearch map]
[BONAP county map]
Discussion

Two varieties have been recognized in Callitriche heterophylla, with var. bolanderi distinguished on the basis of its schizocarps being larger (for example, N. C. Fassett 1951b); however, the size of the schizocarps overlaps widely, and measurements of schizocarps from throughout North America show that there is no clear geographical or ecological separation between plants with smaller fruit and those with larger fruit. Therefore, there is no justification for maintaining the distinction.

Populations of small plants with linear leaves from parts of Canada and Alaska have been separated as Callitriche anceps. However, these appear to represent the lower extremes of variation in C. heterophylla, and morphological characters do not justify maintaining the distinction.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 17, p. 54. FNA vol. 17, p. 51.
Parent taxa Plantaginaceae > Callitriche Plantaginaceae > Callitriche
Sibling taxa
C. brutia, C. fassettii, C. hermaphroditica, C. heterophylla, C. longipedunculata, C. marginata, C. palustris, C. pedunculosa, C. peploides, C. stenoptera, C. terrestris, C. trochlearis
C. brutia, C. fassettii, C. hermaphroditica, C. longipedunculata, C. marginata, C. palustris, C. pedunculosa, C. peploides, C. stagnalis, C. stenoptera, C. terrestris, C. trochlearis
Synonyms C. anceps, C. bolanderi, C. deflexa var. austinii, C. heterophylla subsp. bolanderi, C. heterophylla var. bolanderi
Name authority Scopoli: Fl. Carniol. ed. 2, 2: 251. (1772) Pursh: Fl. Amer. Sept. 1: 3. (1813)
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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