The Mutated Jadinko Male can be located at Dungeon teleports ~> Forbidden Dungeon ~> Run all the way to the end.
(This monster has very high defence, so killing it is not quick and easy.)
Drops:
Whip Vine - 0.2564%
Yew/Magic logs & Jewelry - 11.1111%
Seeds/Herbs - 0.7812%
Other items such as Grenwall spikes, Papaya fruit, and a few others can also be dropped.