In Classic, since biomes arent in Classic, are bright and colorful. The only trees are Oak Trees, since there are no biomes to put Birch Trees (Forest Biomes/ Birch Forest Biomes), Spruce Trees (Tiaga/ Tundra Biomes) and Jungle Trees (Jungle Biomes). In 1.7, two new trees were added; Acacia (Savannah Biomes) and Dark Oak (Roofed Forest Biomes).
Wood Types Edit
Oak, Birch, Spruce, Jungle, Acacia and Dark Oak
Tree Types Edit
Oak: Oak, Large Oak
Birch: Birch, Tall Birch
Spruce: Spruce, Large Spruce, Pine
Jungle: Jungle, Large Jungle
Dark Oak: Large Dark Oak
Trees are one of the first thing a player collects, as wood is the most useful item in Minecraft, used to make everything. Wood can be smelted into charcoal, ideal to make your first torches.