Octopus Tree (CR 12)

Huge Plant
Alignment: Usually neutral evil
Initiative: +0; Senses: Listen +4 and Spot +14

AC: 28 (-2 size, -4 Dex, +24 natural), touch 4, flat-footed 28
Hit Dice: 14d8+70 (133 hp)
Fort +14, Ref +0, Will +6
Speed: 10 ft., swim 50 ft.
Space: 15 ft./15 ft.
Base Attack +10; Grapple +28
Attack: Tentacle +19 melee
Full Attack: 8 tentacles +19 melee and 1 bite +13 melee
Damage: Tentacle 2d6+10/19-20, bite 3d8+5
Special Attacks/Actions: Frightful presence, improved grab, spell-like abilities, swallow whole
Abilities: Str 30, Dex 3, Con 20, Int 8, Wis 15, Cha 15
Special Qualities: Acid immunity, plant traits, regeneration 10
Feats: Alertness; Improved Critical (tentacle); Improved Initiative; Quicken Spell-Like Ability; Weapon Focus (tentacle)
Skills: Listen +4, Spot +14, and Swim +25
Advancement: 15-35 HD (Gargantuan); 36-42 HD (Colossal)
Climate/Terrain: Temperate ocean surface
Organization: Solitary or grove (2-12)
Treasure: Standard

Source: Fiend Folio

Sailors sometimes tell stories of strange and terrible forests of trees in the middle of the ocean; most of these forests most likely had their genesis at the bottom of a mug of grog, but a few certainly come from close encounters with octopus trees.

An octopus tree is a rubbery black-barked tree that roots near shore and stands upright or floats with the currents on the surface of the sea. Many long and numerous broad black roots spread out around its base like a thick mat of seaweed; these roots are mobile and can propel the tree with great speed across the surface of the water. The tree's branches are long, thick tentacles covered with tiny, sharp, dark green leaves. Hidden in the base of the tree's trunk just below the water is a large maw filled with teeth.

Octopus trees are rightfully feared by sailors, for these terrible plants command powerful magical abilities that allow them to wreak havoc on wooden ships. Many large groves of octopus trees have the skeletons of ships lodged among their roots, and many explorers and treasure seekers have been lured to their doom in these dangerous groves.

Octopus trees understand Common, but they lack the body parts necessary for speech.