instruction:
In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant.
question:
The inner portion of the ring is formed during rapid spring growth. The tree's growth slows as the seasons change. The ring's outer growth is more dense. The growth of the tree pushes out the bark of the tree. The tree stops growing quickly in the winter. This seasonal "pause" in growth results in distinct rings in certain tree types.
answer:
bark ,inner portion of the ring

question:
A plant dies and withers. The dead plant starts to draw microbes. The microbes break down the material. Forms decay. The resulting material disappears. The plant becomes one with the soil.
answer:
plant ; material ,microbes

question:
Grass and small plants grow in an area. These plants die. The soil gains organic material. The soil becomes more fertile. Larger plants are able to be supported. Trees eventually grow.
answer:
Grass ,Small plants ,organic material ,larger plants ,trees