|Narrow-Leaved Bur-Reed in Nanton Lake, BC|
At the time we were there, no flowers were visible. Male flowers are on the upper portion of the stem rising out of the water. Female flowers form rough round heads that look like burrs. They are found on the lower portion of the same stem. That arrangement, and growing close to neighbouring plants promotes fertilization.
The burr like fruits and reed shaped leaves give these plants their common name.
Wayne and I saw lots of Bur-Reed on our kayak trip on Nanton Lake near Powell River. It was most prevalent in the back bays and along the shallow shoreline. Because the water level was low, the leaves were very visible floating on the surface. -- Margy
References: Plants of Coastal British Columbia by Jim Pojar and Andy MacKinnon (Lone Pine Publishing, 1994), Wild Berries of the Pacific Northwest by J.E. Underhill (Hancock House Publishers, 1974), and E-Flora BC: Electronic Atlas of the Flora of British Columbia online.