Please see this thread as I've been working through the tables to try and identify the issue;
http://stratics.com/community/threads/comprehensive-plant-list.293828/
In short, originally the bug that was left in by Sakarah allowed fertile variants of 4 plants to be created; Flowered Cactus, Spider Trees, and left and right facing Hops.
A recent patch, I'm not sure which, has made the Plain Spider, Plain Left and Plain Right Hops infertile. They can still be generated via cross breeding elsewhere on the table, but they'll appear with Plain instead of Peculiar seed type.
Also Bonsai trees from the resulting crosses are themselves fertile. I don't have any data yet on what they will always result in when crossed, but plants grown this way now lose the Rarity descriptor and only have the Colour.
http://stratics.com/community/threads/comprehensive-plant-list.293828/
In short, originally the bug that was left in by Sakarah allowed fertile variants of 4 plants to be created; Flowered Cactus, Spider Trees, and left and right facing Hops.
A recent patch, I'm not sure which, has made the Plain Spider, Plain Left and Plain Right Hops infertile. They can still be generated via cross breeding elsewhere on the table, but they'll appear with Plain instead of Peculiar seed type.
Also Bonsai trees from the resulting crosses are themselves fertile. I don't have any data yet on what they will always result in when crossed, but plants grown this way now lose the Rarity descriptor and only have the Colour.