Flora of North America species comparison

The green links below add additional plants to the comparison table. Blue links lead to other Web sites.
enable glossary links

Potamogeton pusillus subsp. tenuissimus

Potamogeton pusillus subsp. pusillus
Photo is of parent taxon

narrow-leaf small pondweed, potamot très ténu, small pondweed
Photo is of parent taxon

potamot nain, small pondweed
Leaves

stipules convolute;

blade 0.9–5.4 cm × 0.2–2.5 mm;

apex acute to obtuse, lacunae in 1–5 rows each side of midrib;

veins 1–3(–5).

stipules connate;

blade 1.4–6.5 cm × 0.5–1.9 mm, apex acute or rarely apiculate, rarely with bristle, lacunae present or absent, 0–2 rows each side of midrib;

veins 1–3.
Inflorescences

peduncles more than 3 per plant, cylindric to slightly clavate;

spikes capitate to cylindric, continuous.

peduncles 1–3 per plant, filiform to cylindric;

spikes cylindric, interrupted.
Fruits

ovoid, sides rounded, rarely concave;

beak median, rarely toward adaxial edge.

obovoid, sides centrally concave;

beak toward adaxial edge, rarely median.
2n

= 26.

= 26 (Eurasia).

Potamogeton pusillus subsp. tenuissimus

Potamogeton pusillus subsp. pusillus
Phenology Flowering and fruiting summer–fall. Flowering and fruiting spring–fall.
Habitat Shallow waters of lakes and streams Streams, lakes, or marshes
Elevation 0–2100 m (0–6900 ft) 0–3300 m (0–10800 ft)
Distribution
from FNA
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KY; LA; MA; MD; ME; MI; MN; MS; MT; NC; ND; NH; NJ; NV; NY; OH; OK; OR; PA; RI; SC; VA; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; Eurasia
from FNA
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; NT; ON; PE; QC; SK; YT; South America; Eurasia; Africa
Discussion

Although Delaware and West Virginia lies within the mapped area, we know of no collections from that state.

Potamogeton pusillus subsp. tenuissimus is the most common linear-leaved subspecies of the family in temperate North America. Whenever one finds a linear-leaved pondweed with 1–5 rows of lacunae on each side of the midvein, chances are that it is subsp. tenuissimus.

Only Potamogeton obtusifolius could be confused with the taxon, and it can be separated by having its cylindric inflorescence, whereas subsp. tenuissimus has a capitate inflorescence.

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

Potamogeton pusillus subsp. pusillus is nearly worldwide. When it is in fruit, the inflorescence is interrupted. That character combined with its narrow, linear, 1–3-veined leaves makes this taxon easily recognized. The nodal glands are green, essentially the color of the stems. Often appearing only as bumps on the stem at the nodes, they are difficult to see. Also, because the glands frequently occur at only a few nodes per plant, one can easily overlook them.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 22. FNA vol. 22.
Parent taxa Potamogetonaceae > Potamogeton > Potamogeton pusillus Potamogetonaceae > Potamogeton > Potamogeton pusillus
Sibling taxa
P. pusillus subsp. gemmiparus, P. pusillus subsp. pusillus
P. pusillus subsp. gemmiparus, P. pusillus subsp. tenuissimus
Synonyms P. pusillus var. tenuissimus, P. berchtoldii, P. berchtoldii var. colpophilus, P. berchtoldii var. lacunatus, P. berchtoldii var. polyphyllus, P. berchtoldii var. tenuissimus P. panormitanus, P. pusillus var. minor
Name authority (Mertens & W. D. J. Koch) R. R. Haynes & Hellquist: Novon 6: 370. (1996) unknown
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).



Type/paste one or more Latin names into the boxes above; matching taxa will show up below the box as you type. You can use the up/down arrow keys to move through the list.

(If the plant you're looking for doesn't show up in the auto-complete list, that means it either isn't described in Flora of North America yet, or it's listed under a synonym. And please note that Flora of North America is still missing several plant families, including Apiaceae, Boraginaceae, and Polemoniaceae.)

Choose a data source: Flora of North America, OregonFlora

The species comparison tool is brought to you by:
Northwest Wildflowers