Hrmm. Your version of DF appears to be different from mine...
I can quickly make you a custom tileset to fix the 28 and 29. But changing tile 181 would change how the edges of horizontal bridges would look. (It is just one of those things that the ol' dwarf fortress and I didn't agree on). I think it tended to pick 181 for withered trees as well. I believe these can be modified in the raws though if it becomes too much of an eyesore. I'll think about the problem... but I found it very difficult to make 181 look both like a tree, and the end of a bridge. It is also a sideways chair and a mine cart track end
To change what Blood thorn would look like for your version just execute your favorite text editor, open DF/raw/objects/plant_standard.txt and under BLOOD_THORN replace the 181 with a tile you think better suited. Your blood thorn may not look like the below example, but is should be the same premise.
[PLANT:BLOOD_THORN]
[NAME:blood thorn][NAME_PLURAL:blood thorn][ADJ:blood thorn]
[USE_MATERIAL_TEMPLATE:STRUCTURAL:STRUCTURAL_PLANT_TEMPLATE]
[DISPLAY_COLOR:4:0:0]
[BASIC_MAT:LOCAL_PLANT_MAT:STRUCTURAL]
[USE_MATERIAL_TEMPLATE:WOOD:WOOD_TEMPLATE]
[STATE_NAME:ALL_SOLID:blood thorn]
[STATE_ADJ:ALL_SOLID:blood thorn]
[PREFIX:NONE]
[STATE_COLOR:ALL_SOLID:CRIMSON]
[DISPLAY_COLOR:4:0:0]
[SOLID_DENSITY:1250]
[TREE:LOCAL_PLANT_MAT:WOOD]
[TRUNK_PERIOD:10]
[HEAVY_BRANCH_DENSITY:25]
[BRANCH_DENSITY:50]
[MAX_TRUNK_HEIGHT:5]
[HEAVY_BRANCH_RADIUS:1]
[BRANCH_RADIUS:2]
[TRUNK_BRANCHING:2]
[MAX_TRUNK_DIAMETER:1]
[TRUNK_WIDTH_PERIOD:200]
[STANDARD_TILE_NAMES]
------->[TREE_TILE:181]
------->[DEAD_TREE_TILE:181]
[PREFSTRING:sickening appearance]
[WET][DRY]
[BIOME:SUBTERRANEAN_WATER]
[BIOME:SUBTERRANEAN_CHASM]
[UNDERGROUND_DEPTH:3:3]
[TREE_COLOR:4:0:0]
[DEAD_TREE_COLOR:5:0:0]
[SAPLING_COLOR:4:0:0]
[DEAD_SAPLING_COLOR:5:0:0]
An alternative is to enter the very fun realm of making your OWN custom tileset! Just download GIMP or open Microsoft Paint and go for it!
I derail.
Feel free to take anything I've done and run with it. Believe it or not, this tileset was based on Lord Dullard's tileset. It all started when I decided to change one tile to look more like a bed.
Custom Tileset for IronSI:
If you (or anyone else) would like me to customize a tileset for them just let me know! I'd love to do it. Straining my eyes at tiny pixels is how I relax