Final Answer:
The mushroom in question is likely a Boletus edulis, commonly known as the porcini mushroom.
Step-by-step explanation:
Boletus mushrooms are characterized by their distinct features, and Boletus edulis, commonly known as porcini, fits the description provided. Porcini mushrooms have a stout stem, a cap with a reddish-brown hue, and a sponge-like pore surface underneath. These mushrooms are highly sought after for their culinary uses and are found in various habitats, including forests with both coniferous and deciduous trees.
The cap of Boletus edulis is usually brown and can range from 5 to 25 centimeters in diameter. Its pore surface is white when young, turning yellow and then greenish-yellow as it matures. The stem is thick and often has a net-like pattern. The overall appearance of the mushroom aligns with the characteristics mentioned in the question.
It's important to note that accurate mushroom identification requires a careful examination of several features, including cap color, pore surface, stem characteristics, and habitat. While the description provided suggests Boletus edulis, it's recommended to consult field guides or seek expert advice to confirm the identification, especially considering the potential risks associated with misidentifying mushrooms. Always exercise caution and, if uncertain, refrain from consuming any wild mushrooms.