Reason for standing under the hemlock tree:
The poet was standing under the hemlock tree because he was feeling burdened by the troubles and challenges of life. The poem "Dust of Snow" by Robert Frost describes how a small moment of nature can have a big impact on our mood and perspective. In the poem, the poet mentions how a crow's sudden movement caused a dust of snow to fall on him, which served as a moment of clarity and relief from his heavy thoughts.

Symbolism of the hemlock tree:
The hemlock tree in the poem symbolizes nature's ability to provide solace and healing. Hemlock trees are known for their dark green foliage and tall, majestic presence. By standing under the hemlock tree, the poet seeks refuge and comfort in nature's embrace. The tree represents a sanctuary where the poet can escape from the chaos of life and find a moment of peace.

Impact of nature on the poet:
The dust of snow falling on the poet serves as a metaphor for how even the smallest joys in nature can lift our spirits and change our perspective. The poet's mood shifts from one of heaviness and despair to one of lightness and gratitude. This simple act of nature reminds him of the beauty and wonder that surrounds him, helping him to see the world in a new light.
In conclusion, the poet was standing under the hemlock tree to seek solace and find a moment of clarity and relief from his troubles. The poem highlights the transformative power of nature and how even the smallest moments can have a profound impact on our lives.