Flora of North America species comparison

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Potamogeton clystocarpus

Potamogeton floridanus

little aguja pondweed

Florida pondweed
Rhizomes

absent.

present.
Cauline stems

terete to slightly compressed, without spots, to 57 cm;

glands white to gold, 0.2–0.3 mm diam.

terete, without spots, ca. 50 cm.
Turions

unknown.

unknown.
Leaves

submersed, ± spirally arranged, sessile, delicate;

stipules persistent, inconspicuous, convolute, free from blade, brown, not ligulate, to 0.62 cm, not fibrous, not shredding at tip, apex obtuse;

blade green, linear, not arcuate, 3.2–7.8 cm × 0.7–1.7 mm, base slightly tapering, without basal lobes, not clasping, margins entire, not crispate, apex not hoodlike, acute, lacunae rarely absent, in 0–4 rows each side of midrib;

veins 3(–5).

submersed and floating, ± spirally arranged.
Floating leaves

petioles continuous in color to apex, 4–6.5 cm;

blade adaxially dark brown, elliptic, 4.5–6.6 cm × 7–12 mm;

base acute, apex acute;

veins 7–11.
Submersed leaves

sessile, lax;

stipules persistent, inconspicuous, convolute, free from blade, whitish, not ligulate, 2.5–4 cm, delicately fibrous, eventually shredding, apex acute;

blade dark green to olive-green, narrowly linear, not arcuate, 15–20 cm × 0.7 mm, base attenuate, not clasping, not lobed, margins entire, not crispate, apex not hoodlike, acute, lacunae absent;

veins 1.
Inflorescences

unbranched, emersed;

peduncles not dimorphic, axillary or terminal, erect, cylindric, 3.2–4.8 cm;

spike not dimorphic, capitate to cylindric, 5.5–7.5 mm.

unknown.
Fruits

sessile, brown to yellow-green, obovoid, compressed, abaxially and laterally keeled, 2–2.2 × 1.7–1.8 mm, lateral keels without points;

beak erect, 0.5–0.6 mm;

sides with 1–3 tubercules near base;

embryo with 1 full spiral.

unknown.

Potamogeton clystocarpus

Potamogeton floridanus
Phenology Flowering and fruiting spring–summer. Flowering and fruiting unknown.
Habitat Small streams Shallow waters of flowing streams
Elevation ca. 1800 m (ca. 5900 ft) 0–10 m (0–0 ft)
Distribution
from FNA
TX
[BONAP county map]
from FNA
FL
[BONAP county map]
Discussion

Potamogeton clystocarpus is an extremely limited species known from only one canyon in west Texas.

Of conservation concern.

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

Potamogeton floridanus is an extremely localized species of the panhandle of Florida. No one has treated the species recently (E. C. Ogden 1943; R. R. Haynes 1978). Four populations of the taxon were reported from Santa Rosa County, Florida (G. S. Wilhelm and R. H. Mohlenbrock 1986). Those populations clearly match the protologue and the original collections. One population has recently been found fertile (J. R. Burckhalter, pers. comm.), but we have not examined the specimens. Because the taxon persists and has a vegetative morphology unlike any other pondweed, we believe it must be recognized. Until a better understanding of the taxon is developed, we prefer to recognize it at the specific level.

Of conservation concern.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 22. FNA vol. 22.
Parent taxa Potamogetonaceae > Potamogeton Potamogetonaceae > Potamogeton
Sibling taxa
P. alpinus, P. amplifolius, P. bicupulatus, P. confervoides, P. crispus, P. diversifolius, P. epihydrus, P. floridanus, P. foliosus, P. friesii, P. gramineus, P. groenlandicus, P. hillii, P. illinoensis, P. natans, P. nodosus, P. oakesianus, P. oblongus, P. obtusifolius, P. ogdenii, P. perfoliatus, P. praelongus, P. pulcher, P. pusillus, P. richardsonii, P. robbinsii, P. spirillus, P. strictifolius, P. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
P. alpinus, P. amplifolius, P. bicupulatus, P. clystocarpus, P. confervoides, P. crispus, P. diversifolius, P. epihydrus, P. foliosus, P. friesii, P. gramineus, P. groenlandicus, P. hillii, P. illinoensis, P. natans, P. nodosus, P. oakesianus, P. oblongus, P. obtusifolius, P. ogdenii, P. perfoliatus, P. praelongus, P. pulcher, P. pusillus, P. richardsonii, P. robbinsii, P. spirillus, P. strictifolius, P. subsibiricus, P. tennesseensis, P. vaseyi, P. zosteriformis
Name authority Fernald: Memoirs of the american academy of arts and science n.s. 17:79, plates 15, 30, fig. 5. (1932) Small: Flora of the Southeastern United States 37, 1326. (1903)
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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