oiしげshigeru
1.

To flourish and grow densely, often referring to plants or foliage becoming lush and full.

2.

To spread vigorously with many branches and leaves, indicating a healthy and abundant growth, particularly during warm seasons.

3.

To become excessively crowded by vegetation, resulting in an area being overtaken by wild or unmanaged plant life.

Example:

その木々は葉が生い茂っている。

しげshigeru
1.

To grow densely, where branches and leaves spread out vigorously, often overlapping each other, creating a lush and vibrant appearance.

2.

To flourish in a way that results in a rich and abundant growth of foliage, suggesting vitality and strength in plants.

3.

To become densely packed with vegetation, indicating a state where leaves and branches emerge closely together, often creating a thicket-like environment.

Example:

丘には低い木がたくさん茂っている。