Potamogeton praelongus
White-stemmed pondweed
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Family: Potamogetonaceae · Type: Herb · Native
Conservation status: CNPS 2B.3
Potamogeton praelongus (White-stemmed pondweed) is a native California herb in the Potamogetonaceae family, recognized by white stems and hooded leaf tips that split when dry absolutely distinctive.
White-stemmed pondweed is a California native perennial found in northern and central Sierra Nevada Mountains in deep water and lake habitats at elevations of 1,800 to 3,000 meters. Flowering from July to August, this aquatic plant produces small flowers on slender peduncles 10 to 30 centimeters long. Growing with stout rhizomes and stems less than 30 centimeters tall, it develops few branches that often grow in a distinctive zigzag pattern. Its submersed leaves are lance-linear, 5 to 20 centimeters long and 10 to 30 millimeters wide, with wavy edges and base lobes that clasp the stem. The distinctive white-colored stems and stipules, along with leaves that split when dry, make this pondweed a unique aquatic species.
Identification and appearance
Key characters: 7 sympatric species; white stems and hooded leaf tips that split when dry absolutely distinctive
Habitat and range
Habitat: Deep water, lakes
Elevation: 1800-3000 m
Outside California: to Alaska, Greenland, Mexico, Europe, eastern Asia
Bloom period
Potamogeton praelongus blooms Jul-Aug.
Conservation status
CNPS 2B.3
How to tell it apart
vs Persicaria: Potamogeton flowers float on water; Persicaria has terrestrial pink/white flower spikes above solid ground.; vs Stuckenia: Potamogeton flowers emerge above water on stiff stalks; Stuckenia flowers stay underwater on flexible stalks.; vs Alisma: Potamogeton has inconspicuous spike flowers; Alisma has showy white three-petaled flowers in branched clusters.; vs Ranunculus: Potamogeton has tiny greenish spike flowers; Ranunculus has bright yellow buttercup flowers with visible petals.; vs Myriophyllum: Potamogeton has broad or ribbon-like leaves; Myriophyllum has feathery, finely divided leaves like a bottlebrush.
Frequently asked questions
Is Potamogeton praelongus native to California?
Yes. Potamogeton praelongus is native to California (recorded as native).
When does Potamogeton praelongus bloom?
Potamogeton praelongus blooms Jul-Aug.
What plant family does Potamogeton praelongus belong to?
Potamogeton praelongus is in the Potamogetonaceae family, genus Potamogeton.
Is Potamogeton praelongus rare or endangered?
Potamogeton praelongus carries California Rare Plant Rank 2B.3, state rank S2.
What habitat does Potamogeton praelongus grow in?
Potamogeton praelongus grows in Deep water, lakes.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.