Don't go into the bonegrass. Seriously, unless you want to be dead. You go in there, brush the grass with your clothes, start to feel sleepy...
Before too long your limbs will go numb, then you're on the floor in a heap. Then you're dead but you don't know it yet. The grass you crush as you fall will grow up through your bones, your flesh will feed its neighbours and your blood will water its children.
Oh, and did I mention you being awake right up until you're dead?
Bonegrass (so called because of its bone white colour and propensity for killing things) is a rapidly growing (4–5cm/day) form of wheat. It grows to its full height in just under a month, emits specialised paralytic pollen and then uses the nutrients of its prey to fuel its growth and spread (as most prey succumbs near the edges of the bonegrass field). Its seeds are heavy and lay dormant on the ground until something falls on them, at which point they have a growth spurt and start to work their way up through the prey.
The prey (for their part) are enticed to the bonegrass fields because it's a remarkably good source of nutrition if you don't fall down and die before getting away. The seeds (to fuel their rapid growth spurt) pack a lot of calories.
The question is how often a patch of bonegrass would need to capture and kill (non-sentient) prey in order to maintain a balance between 'enticing food source' and 'deadly patch of death, do not approach'. This is going to affect how the densities of the paralytic pollen change over time, varying between attracting prey with free food and then killing everything in order to spread a bit further.