It's the 'Yellow Walking Iris'. This sun, heat, humidity and drought hardy plant stays green all year and grows in grassy clumps to around a metre in height . You can see clumps of Neomarica to the right of the photo below.
I have lots of it growing in the protected environment of my greenhouse garden and in the shaded beds under my pergola, but it is also growing in full sun in some of my outdoor garden beds. It is safe to say that this plant will tolerate the full spectrum of light, from full sun to fairly deep shade, although more sun always equals more flowers. It can even be grown indoors.
However, I find, the best location is a place where there is bright broken light. When it is growing outdoors in the full sun, the leaves do get a little burnt and perhaps don't look their best. In spite of this, it is commonly used by landscapers for outdoor garden spaces ... we have lots of it growing in the beds at my school.
The sword like leaves grow in a fan shape, and are around 1 inch wide.
The plant flowers intermittently all year, peaking in the spring and summer. The delicate iris flowers are bright yellow with mottled brown spots.
Nearly open ....
Each flower lasts only one day, but another flower will quickly take it's place the following day.
As the flowers fade, tiny plantlets with air roots develop on their stems, and as these mature, their weight causes the leaves to bend down and touch the ground (ie ‘walk’).
You can easily snip off the plantlets when air-roots appear, and either replant them for new plants, or just get rid of them – either way, clipping them off will promote more flowering. The new plantlets will take 1 - 2 years to bloom, depending on climate and care.
Although Yellow Walking Iris will tolerate dry conditions quite well, it prefers moderately damp (but well drained) soil. Mulch is not necessary, and if it is used, it should not be heavy or packed closely around the bottom of the plants, as the rhizome roots may rot if soil is too moist. Water more often in warm months, keep fairly dry when cool.