Quote Originally Posted by Beni-Kujaku View Post
Where did you find that? That would be extremely uncomfortable and remove most of the combat ability of the Tendriculos, but it would be incredibly cool to see a tendriculos come up to you, open its mouth, and you see a wizard casually walking off it.
Arms & Equipment Guide, pg 87. The seed costs 3,000gp, and if you pay to have it trained that's another 2,000 (or you could make the DC 27 check to rear it yourself). Like you said, it's not the most effective mount, but sometimes you just have to go for novelty and style.