* Rye is a type of cereal grain, but it's derived from a species of grass (ryegrass).
* Oats are also a cereal grain, specifically the seeds of a grass species called oat.
* Buffalo is a type of grass that is often used for lawns and pastures.
* Kikuyu is another type of grass, known for its rapid growth and tolerance to drought.
Therefore, the commonality between rye, oats, buffalo, and kikuyu is that they are all different types of grass species.