This mod adds more trees, without adding more biomes, to make the world more vibrant, but not too complicated. All trees are variants of the normal minecraft trees, to feel like a part of the world.

The trees are:
Mossy Oak, a greener variant of the Oak replacing Swamp Oak Trees. Has 2 shapes.
Azalea, a new wood set for the already existing Azalea Tree, to make it feel like its own thing.
Red Oak, a bright-ish red variant of the Oak meant to bring more color to (dark) forests. Has 3 shapes.
White Birch, a Birch variant without those annoying black spots, made to fit in with Birch Wood. Has 1 shape.
Pine, a lighter Spruce variant made to make all spruce biomes a bit brighter. Has 2 shapes.
Purple Acacia, a vibrant Acacia variant to make savanna biomes feel a bit more hopeful. Has 1 shape.
All trees have a complete woodset (including signs and boats).

This mod also changes the following Minecraft trees:
Oak (the smaller trees are taller and have a thicker tree trunk size at the bottom)(added a mega variant);
Birch (they have thinner foliage and rarely branches)(added a mega variant);
Spruce (their spruce variant's foliage is pushed up, their pine variants have thicker trunks);
Azalea (has a seperate woodset from Oak)(added a mega variant).

This mod also adds 7 new grass types, to bring yet another bit of variation to some empty feeling biomes. You need Shears or Silk Touch to get them, so they won't clutter your inventory.

From left to right:
Swamp grass, to make swamps feel a bit more overgrown while being easy to see trough.
Grassy Flower and Small Grassy Flower, to make the empty snowy biomes have a bit more life.
Short and Tall Mycelium Grass and normal, Brown and Red Spore Grass to have a bit more vegetation in the Mushroom Fields.

This mod also adds 5 decoration features to the Nether and 2 to the End.
Those are made to just give a bit more variation, without adding more blocks.
Showcase pictures of the Nether/End decorations are in the gallery.

More showcase pictures in the gallery.

Mod status: complete unless I get more ideas (or possible bugfixes).

Feel free to comment ideas or bugs.
Feel free to put into a modpack.
Feel free to port the mod over to another version/modloader/site/app.

Simplicity Biome Overhaul