My neighbor down the street gave me what he told me were "tiger lily" seeds (lilium lancifolium). The plant is maybe 2-3' tall, with deep orange sharply recurved lilies with spots on them. It's not what I typically call a tiger lily, which is the orange North American daylily-esque "ditch lily." Since these develop the "seeds" at the base of the leaf, there seem to be quite a few on the plants. How invasive is this plant? My neighbor has his next to a concrete walkway, so much of the "seed" never propagates. I was thinking of putting them in the backyard bed, but not if I'll shortly be overrun. The USDA website lists it as an invasive or noxious weed, but then again they list bleeding heart, honesty, rose campion, and maltese cross, to name a few plants in my garden without problems.

Thanks in advance for any assistance.