I was friendly with the Rev.C.E.Shaw (no relation) in my youth - he was an author of the then local flora if I remember rightly. We went on several outings, one along that canal and another to Nob End, a Victorian alkaline waste site which had an incredible assemblage of exotic plants. He had a real penchant for waste tips! We also took him up Penyghent once to see the purple saxifrage, which he'd never seen before. I knew the flora of the Bury-Bolton canal quite well and I have my detailed notebooks still from the early 70s. Last time I looked it seems that Water Soldier had gone a bit rampant, a plant I didn't see there at all 40 years ago. There are a couple of spots where Royal Fern poked out of the towpath wall, one near Bury and the other, which I believe I was the first to find, near Radcliffe town centre.