Hemerocallis, or more commonly known as Day Lily due to the fact the flowers last one day. Has beautiful green foliage that are strap shaped and tend to go floppy towards the end of the season. The plant spreads by rhizomes that's travel under the ground and can be quite invasive if not controlled properly. Day lilies should be split every few years, they can become quite crowded quickly. I split mine at least every 3 years, when splitting two forks should be used to prize the plant apart, Do not use a spade as this will slice the roots off to violently. Also you should make sure there are at least 3 fans (a fan is the growth part of the plant you can see above the soil) you will lose some roots of the plant during the split, but it will recover quite quickly. Failing to split the plant will result in less flowers.