The water drops that are seen on the tips of leaves in grasses and common garden plants in the early morning hours are obtained from hydathodes.

Option 1, the atmosphere, is not the source of the water drops. While the atmosphere does contain water vapor, it is not responsible for the water accumulation on the leaves.

Option 2, stomata, are tiny openings present on the surface of leaves that allow for the exchange of gases. These openings can release water vapor, but they are not responsible for the water droplets that are observed on the tips of leaves.

Option 3, vascular bundles, are structures within plants that transport water, nutrients, and sugars. While they play a role in the movement of water within plants, they are not responsible for the water accumulation on the tips of leaves.

Option 4 is the correct answer. Hydathodes are specialized structures found on the leaf margins or tips. They are responsible for the excretion of water droplets, a process known as guttation. These droplets are a result of excess water pressure within the plant and are often seen in the early morning hours when transpiration rates are low.