Which of the following fuels burns the hottest and fastest?

Grass is considered to burn the hottest and fastest among the fuel types listed. This is primarily due to its finely textured, low moisture content, and high surface area-to-volume ratio. These characteristics allow grass to ignite quickly, leading to rapid flame spread.

Grass fires typically generate high temperatures and move swiftly because the fuel is not only abundant but also easily accessible for ignition. When conditions are dry and wind is present, grass can facilitate extreme fire behavior, resulting in a fast-moving fire front that can pose significant threats to safety and firefighting efforts.

While shrub and timber-understory fuels can also contribute to intense fires, they generally burn slower than grass because of their thicker structure and potential moisture content. The grass-shrub combination could increase fire intensity compared to grass alone but still may not reach the speed and heat of pure grass fires. Therefore, grass is the most likely candidate for burning the hottest and fastest in wildland fire scenarios.