This pondweed was not described as a separate species until 1983 and honors Dr. Eugene Ogden, former New York State Botanist and pondweed specialist.
There are only three known populations. These populations may be threatened by the use of aquatic herbicides. As more surveys are conducted, new populations may be encountered. With so few populations now known though, this plant will likely remain rare long into the future.
As a relatively newly described species, there is not a lot of historical evidence to determine a trend. Based on minimal evidence, populations are presumed stable. There is a possibility that more populations will be discovered in the future.
This pondweed was always very rare in New York. As a relatively new species originating from a hybrid cross, there is a chance that this species will be found in new locations as people better understand how to identify it and as the species possibly establishes itself in new areas.
Water quality deterioration from increasing shoreline development and the use of herbicides to control invasive aquatic plants could threaten this plant if these activities are not carefully planned. It may also be threatened by lake eutrophication due to runoff from nearby activities.
No direct management is required for this species; however, in areas where recreational activities are also present there should be monitoring efforts to minimize the impact of changes in water quality, motor boats, and the use of aquatic herbicides.
Research is needed to determine how different aquatic herbicides affect this plant.
An aquatic plant of alkaline waters, including slow streams, calcareous ponds, muddy shorelines, and lakes without high horsepower boats (New York Natural Heritage Program 2004). Alkaline waters of ponds and lakes (Flora of North America 2000). Alkaline waters (Gleason and Cronquist 1991).
This aquatic plant is limited to the alkaline waters near the foothills of the Taconic Ridge and disjunct to at least one local population in central New York (Oswego County). More survey work should be conducted in the alkaline waters of eastern New York, Oswego County, and the Finger Lakes region.
This aquatic plant has a very limited distribution. It is only known from Massachusetts, Vermont, and New York.
This is an aquatic plant with masses of long, very narrow leaves visible just below the surface of waters with a high pH. There are three, sometimes five veins running the length of the leaf. There are one or two rows of large open cells on either side of the mid-vein and often, but not always, a little bristle at the tip of the leaf. It is often in fruit with small clusters of fruits at the end of short arching stalks. The fruits are large for a pondweed .
This pondweed has a stem that is round or only slightly flattened. All leaves are submersed and 1-3 mm broad with 5-11 (3-13) veins. The peduncles are mostly terminal. Winter buds are uncommon but when present these are stiff with the outer flat leaves ascending or with inner and outer leaves occasionally undifferentiated. The stipules are brown (rarely white) and fibrous only at the tips. There are 2-4 (0-6) lacunae bands per leaf.
This plant can be identified vegetatively. If found, vegetative material with submerged leaves and stipules should be nicely pressed. This will allow for easier verification later.
Odgen's pondweed (Potamogeton ogdenii) is a species of hybrid origin between Hill's pondweed (Potamogeton hillii) and flat-stemmed pondweed (Potamogeton zosteriformis). Subsequently, it has characteristics resembling both. Potamogeton hillii has 3 (-5) veins, the diameter of the nodal gland is 0.1-0.3 mm or absent, the peduncles are mostly axillary and 6-14 mm long, and the spike is globose and 4-7 mm long. Potamogeton zosteriformis has submersed leaves with 15-35 veins, is 2 or more mm wide, and is stem flattened. The closely related hybrid Potamogeton x longiligulatus (a hybrid between Potamogeton strictifolius and Potamogeton zosteriformis) has 5-18 veins, the diameter of the nodal gland is 0.1-0.4 mm or absent, the peduncles are mostly terminal and 15-30 mm long, the spike is cylindrical and 10-35 mm long, and it rarely fruits (fruits have only been observed once).
Vegetative plants can be seen from early July to mid-September. This pondweed rarely sets fruit. Surveys are best conducted between July and early September.
The time of year you would expect to find Ogden's Pondweed vegetative in New York.
Potamogeton x ogdenii Hellquist & R.L. Hilton
This pondweed is possibly a hybrid between Potomogenon hillii and Potomogenon zosteriformis but it is rarely found with both its parents. Once established, it does appear to produce fertile fruit.
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Flora of North America Editorial Committee. 2000. Flora of North America north of Mexico. Vol. 22. Magnoliophyta: Alismatidae, Arecidae, Commelinidae (in part), and Zingiberidae. Oxford Univ. Press, New York. xxiii + 352 pp.
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Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. The New York Botanical Garden, Bronx, New York. 910 pp.
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Hellquist, C.B., and R.L. Hilton. 1983. A new species of Potamogeton (Potamogetonaceae) from northeastern U.S. Systematic Botany 8(1): 86-92.
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Information for this guide was last updated on: February 15, 2005
Please cite this page as:
New York Natural Heritage Program. 2021. Online Conservation Guide for Potamogeton x ogdenii. Available from: https://guides.nynhp.org/ogdens-pondweed/. Accessed October 16, 2021.