You encounter a plant that has green structures on tall brown stalks which kind of plant is this and what are the green structures

This is a corn plant, and the green structures are the corn cobs.

Based on the description provided, the plant you have encountered could potentially be a type of grass or a similar plant. The green structures on tall brown stalks are likely to be the leaves or blades of the plant.

To identify the plant you encountered and determine what the green structures are, you can follow these steps:

1. Observe the physical characteristics: Take a closer look at the plant and note its overall appearance, including the shape and size of the green structures and the height and color of the stalks.

2. Consult a field guide or plant identification resource: Use a field guide specific to your region or an online plant identification tool. These resources often provide descriptions, images, and key features of different plant species. Look for plants that match the observed physical characteristics.

3. Cross-reference with known plant species: Once you have a few potential matches from the identification resource, compare them to well-known plant species. Look for similarities in leaf shape, size, and arrangement, as well as any unique features like flowers or fruits.

4. Consult a botanical expert: If you are still unsure about the plant's identity after using available resources, seek the advice of a local botanist or a horticulturist who can help you identify the plant accurately.

Without more specific information about the plant's characteristics, it is challenging to accurately determine its identity and the green structures. However, common plants with tall brown stalks and green structures, such as leaves or flowers, could include sunflowers, cornstalks, or lilies.