Contains 10 accepted taxa overall.
Characteristics
Classification
Citation
POTAMOGETON Linnaeus, Sp. Pl. 126. 1753.
-
TYPE: Potamogeton natans Linnaeus Lectotypified by Taylor, in Britton, N. Amer. Fl. 17(1): 14, 30. 1909.
Species
| Scientific Name | Common Name | Herbarium Specimens | Status | Photos |
|---|---|---|---|---|
| Potamogeton crispus | CURLY PONDWEED | Not Native OBL (NWPL) | ||
| Potamogeton diversifolius | WATERTHREAD PONDWEED | Native OBL (NWPL) | ||
| Potamogeton epihydrus | RIBBONLEAF PONDWEED | Native OBL (NWPL) | ||
| Potamogeton floridanus | FLORIDA PONDWEED | Native Endemic Endangered-State OBL (NWPL) | ||
| Potamogeton foliosus | LEAFY PONDWEED | Native OBL (NWPL) | ||
| Potamogeton illinoensis | ILLINOIS PONDWEED | Native OBL (NWPL) | ||
| Potamogeton nodosus | LONGLEAF PONDWEED | Native OBL (NWPL) | ||
| Potamogeton perfoliatus | CLASPINGLEAF PONDWEED | Native OBL (NWPL) | ||
| Potamogeton pulcher | SPOTTED PONDWEED | Native OBL (NWPL) | ||
| Potamogeton pusillus | SMALL PONDWEED | Native OBL (NWPL) |
Identification Key
1. Submersed leaf blade filiform, linear, or ribbon-like, 0.1-10 mm wide
2
1. Submersed leaf blades broadly linear-oblong, lanceolate, elliptic, to nearly orbiculate, 3-58 mm wide (occasional stranded plants without submersed leaves)
7
2. Rhizomes present; floating leaves present, at least in some plants in population
3
2. Rhizomes absent; floating leaves absent
5
3. Lacunae absent in submersed leaves
3. Lacunae prominent in submersed leaves
4
4. Stipular sheaths of submersed leaves adnate to base of leaf blade, tip projecting as ligule; submersed leaf blades to 2 mm wide; floating leaf blades 0.8-1.6 cm long; submersed peduncle axillary and recurved, emersed axillary or terminal and erect to slightly recurved; submersed spike capitate, 2-3 mm long, emersed cylindric, 5-9.7 mm long; fruit lateral wings with sharp points …
4. Stipular sheaths of submersed leaves free from base of leaf blade or with only 1/–5 sheath adnate, ligule not obvious; submersed leaf blades 1-10 mm wide; floating leaf blades 2-8 cm long; peduncle axillary, erect; spike cylindric, 8-40 mm long; fruit with lateral keels lacking sharp points
5. Fruits with abaxial keel or ridge; turions common; peduncle 0.3-1.1(3.7) cm long; embryo with 1 full spiral
5. Fruits with abaxial surface rounded; turions uncommon; peduncle 0.5-6.6 cm long; embryo with <1 full spiral
6
6. Leaf blade with 0-2 rows of lacunae along midrib, apex acute, rarely apiculate, rarely with bristle; stipules connate; peduncles filiform to cylindric, 1-3 per plant; inflorescences interrupted; mature fruits obovoid, sides concave, beak toward adaxial edge, rarely median …
6. Leaf blade with 1-5 rows of lacunae along midrib, apex acute to obtuse; stipules convolute; peduncles cylindric, more than 3 per plant; inflorescences continuous; mature fruits widest at middle or ovoid, sides rounded, beak median, not toward adaxial edge
7. Stem flattened; leaves mostly submersed (sometimes floating or stranded), blade margins conspicuously serrate; fruit beak 2–3 mm; turions formed, hard
7. Stem terete; leaves only submersed (in P. perfoliatus) or submersed and emergent, blade margins entire; fruit beak 1 mm or less; turions rarely formed
8
8. Submersed leaves clasping stem; floating leaves absent (leaves sometimes at the surface or stranded)
8. Submersed leaves petiolate or sessile (not clasping); floating leaves present
9
9. Stem conspicuously rusty- or black-spotted; floating leaf blade 1.2-3.2 times as long as wide, 1.5-5 cm wide, rounded to cordate at base; submersed leaf blades crispate, mostly arcuate
9. Stems without conspicuous dark spots; floating leaf blade 2.2-11 times as long as wide, rounded-acute to cuneate at base, usually tapering to petiole, 1-3 cm wide; submersed leaf blades flat or crispate, mostly not arcuate or occasionally arcuate
10
10. Submersed leaves sessile or petioles 0.1-4 cm long, the petioles usually shorter than the blade; larger submersed leaves acuminate; fruits grayish green to olive-green
10. Submersed leaves with petioles (0.5)2-13 cm long, the petioles usually subequal to longer than the blade; larger submersed leaves acute at apex; fruits red to reddish brown
Genus Synonyms
| Synonym | Full Citation | Basionym | Type |
|---|---|---|---|
| Spirillus | Spirillus J. Gay, Compt. Rend. Hebd. Seances Acad. Sci. 38: 703. 1854. | TYPE: Non designatus. |