I have found this plant which has 1" to 2.5" leaves this time of year. It grows as emergent or submerged on the bottom detritis in ditches or fast flowing seasonal streams. It is easily disturbed in shallow water and floats to the surface with small roots. It appears to be whorled with the leaves coming out from the root or rhizome. Leaves may have a pointed or rounded tip. It has a central midline down each leaf. The very fine veins (best seen backlit from the back side of the leaf) start from the mid-rib and follow the edge of the leaf. The basal leaves die back. Most plants seem to be host to a brown scale-like oval egg mass that is flat on the plant side and peels off easily. Appears to send out runners to reproduce as they often grow in a line. Attached are several photos.
Reminds me a Stratiotes aloides, but it is European species (invasive in Ontario). stratiotes aloides - Google Search Could also be a Sparganium Clip D497_3_003, from Dissolve
It's similar to straiotes but it has actual leaves. The straiotes looks like it has more spear-like with full attachment at the base. The burr reed is closer. Compared to the plant at :01 (that looks like a bladderwort), the burr reed looks much larger leafed at this point than the mystery plant. May be in when it's small it looks different. Possibly same family though. Tthe small burr reed S. minimum in it's winter form is a possibility. Thanks! I'll keep digging.
Heterophyllia (different form of leaves depending on water temperature, water level and season at the time of leaf formation) is pretty common at water plants. If these leaves were a little narrower, then I suspected Littorella uniflora. And I think, it is possible, that there is some kind of Potamogeton.
I wish it was Littorella uniflora as I would love to use this with a cold water aquarium! LOL! This plant has more leaf-like than grass-like leaves. I ruled out the three Potamogeton that are pictured in Pojar and Mackinnon, unfortunately. :) Thanks for the try!
Have you looked at the 20 Potamogeton species in the E-Flora BC scrolling species list? (Thank goodness the E-Flora BC website is up and running again!)
To my eye https://newfs.s3.amazonaws.com/taxo...-alpinus-potamogeton-foliosus-co-dcameron.jpg is similar to your https://forums.botanicalgarden.ubc.ca/attachments/img_7688-copy-jpg.170833/
