Hi Toixtln,
Your plant is actually a succulent. It doesn't like to be wet in the winter. It may staying too wet when you water and it also may need to be repotted. Take a look at these sites to see if that helps.
http://www.rareflora.com/pachypodiumla.htm
http://davesgarden.com/pdb/go/509///
http://forums.gardenweb.com/forums/l...084221787.html
Hope this helps,
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.