|The Sims||The Sims 2||The Sims 3||The Sims 4|
If you like the patch of plantsim leaves, or if you have a mod which allows plantsims to keep their hair, and are disappointed by the plantsim witch-hat, then all you need is the FFS Lot Debugger, often known as the 'Batbox'. You can get it from "More Awesome Than You", which is a well-known Sims 2 and Sims 3 modding site full of useful mods and hacks for your games.
The Lot Debugger must be used with respect and care, as misusing it - especially when in 'boolprop' or debug mode - can cause problems for your game. To remove plantsim witch-hats, all you have to do is click on the lot-debugger and select 'fix' from the pie menu. From there, among the options you will get will be 'flashing blue...'. Click on that and you will get the names of all the sims on the lot. If one of them is a plantsim witch, select the name of that sim and make sure the sim you are controlling has no other actions in his or her queue. The 'change appearance' window will open, and even if the sim whose appearance is being changed is a plantsim, the hair option will be available. In fact, the hat or plantsim hair will be replaced with one of the hair-types in the window, and will likely be the genetic color of that individual. You can keep the hair that is shown in the preview, or choose a different type.
Note that if the plantsim with changes alignment, the hat will return; all you have to do is 'fix flashing blue' again, and your sim will look the way you want him or her to look - because there are many players who are turned off by the similarities of the witches and plantsims, but now they can all look unique!
Also note that plantsims, despite having only three visible motives, will have deep red moods if you only fill the sunlight, water and love (social) motives; they also have invisible comfort and fun motives. The player might not notice this unless the sim is bored and standing for long periods of time.