Trees:
When you start up your Tamagotchi+ Color it will already have a packet of mystery tree seeds and a watering can. If you use the mystery tree seeds, your tamagotchi will plant a seed and water it. A few seconds later you will see it sprout. Every time your tamagotchi wakes up and goes outside, the tree will grow up another stage. The stages are seedling, sapling, young tree, and full-grown tree.
What the tree turns into is determined randomly if you have planted mystery seeds. If you have planted other types of trees from the special seeds, however, the outcome is fixed. The downside to mystery seeds are that sometimes the tree is a poop tree or a worm tree and the tamagotchi becomes unhappy. Here is a list of the trees the mystery seeds can grow into:
Bad Trees:
Poop tree
Worm tree
Neutral/ Item-Giving Trees:
Dumbbell tree
Book tree
Aging Box tree
Piano tree
Paint-Set tree
Bow tree
3-D Glasses tree
Cotton candy tree
Good Trees:
Money tree
The mystery tree is certainly worth growing at least until you get all the item trees despite the fact that it will make your tamagotchi unhappy some of the time. (Also cuz you get money!) There is a little cheat to make it grow up faster. After planting the tree, go to the time screen and set the time to 6:59, a minute before the tamagotchi wakes up at 7:00. When it wakes up, go outside and watch your tree grow. If you do this three times, your tamagotchi's tree should be full-grown. The only catch is that you have to give your tamagotchi a bath every time it wakes up or the next time it wakes up it will be dirty (brown all over.)
If you would like a faster, easier way, go to the store and buy the yellow transit pass. This allows you to go to the Tama Depa. Once there, after saving 3600 Gotchi Points, you can buy the tree growth potion. If you use this, the tree grows up immediately.