Here are some photos I just took in my yard of Spanish Bluebells and why I consider them aggressive weeds. Please note that I never planted them, they have spread by seeding and I've been digging them out twenty years....all these beds were lawn when we bought the house but there were some Spanish Bluebells in the neighbor's yard and on the side of the house by a big Hydrangea that seeded....Yes, I know I've got other weeds too ;) They grow up into the crowns of other plants and are very hard to dig out. They just finished blooming so they aren't as easy to see in the photos. They'll turn yellow in a couple of weeks and get very slimy and attract slugs like crazy too.

I have spanish bluebells growing in the woodland. Most areas receive too much shade and the foliage just flops and smothers smaller plants and I attempt to dig those out each year, but they are prolific from any tiny bulb left in the ground. The ones in a sunnier area with perhaps an hour of sun each day bloom pretty well. I'm pretty sure I read in a catalog the same as you state, that the english bluebells have flowers on one side of the stalk.

It is the most beautiful spring ephemeral, isn't it? If you plant Priumula veris and Primula vulgaris nearby they will bloom at the same time and complement each other very nicely. I let my Mertensia set seed and spread on its own. Now it has spread all over my garden. It is a wonderful sight in spring.

I did a Google search for Virginia bluebell roots and clicked the ‘images’ button and got this There are quite a few pictures there that look like yours (if the link doesn’t work, try to do your own Google image search...) ACK! The link didn't appear at all! Try a Google search....