From Lost Fables Wiki
Swiftgrass is the curious result of a low grass which grows on many of the dunes across the old world coming into contact with a dry lightning storm. When this dry lightning strikes the dune, a small crater of glassed sand is created, and any of this low grass which is on that hill is transformed into Swiftgrass.
Swiftgrass looks much like the short grass that it was in life, but silvery and metallic instead of green and vibrant.
The grass, in life, does not flower. In fact, it just barely clings to life, and without the interference of growers its life cycle is very short, with the grass drying up and dying, then forming tumbleweeds in the wind which spread its seeds far and wide, to occasionally take root somewhere else.
Daylight or Nocturnal Activity
The dry lightning storms which cause swiftgrass typically only happen during the night.
Swiftgrass is not usable for food, and in fact is sharp and hard, making eating it a very poor decision unless thoroughly ground into a powder and incorporated into something else. When it is used, it is almost exclusively ground into fine powder and mixed into potions to cause their effects to come on faster, or if it is the primary ingredient, to speed up the imbiber.
If cared for, the grass which is transformed into swiftgrass can be grown as dense as any normal grass. Commonly it is grown with short lightning rods pressed into the sand among the grass to cause more lightning strikes among it.
This grass grows relatively fast, being at its max height of two feet and ready to be struck by lightning in three or four months.