Question: Are the daylilies I see growing along roadsides native plants? I live in Connecticut.
Answer: No. They are likely the daylily species Hemerocallis fulva, an orange-flowered species native to much of Asia. Hemerocallis fulva is commonly called tiger lily, roadside lily, outhouse lily, ditch lily and tawny daylily. It was introduced to North America most likely in the 1790s, as a garden plant. Stands of tiger lily often mark the sites of old homesteads. It was also used for erosion control; its thick tuberous roots do well to hold soil in place.
This daylily species quickly escaped from gardens to the wild. It has naturalized in 42 states. It spreads by 12-inch-long underground stems, or stolons, not by seed. Its network of stolons and roots make it difficult to fully dig out; any bit of root left in the ground can generate a new plant. It is now listed by a number of states as an invasive plant.
The hybrid daylilies sold at garden centers are clump forming and they set seed; they are not stoloniferous like tiger lily. You should not fear that they will take over your garden or escape into wild areas.