Bonetree (CR 5)

Huge Plant
Alignment: Always neutral
Initiative: +0; Senses: tremorsense 60 ft.

AC: 12 (-2 size, +4 natural), touch 8, flat-footed 12
Hit Dice: 11d8+55 (104 hp)
Fort +12, Ref +3, Will +3
Speed: 0 ft.
Space: 10 ft./10 ft., 30 ft. with stinging vines
Base Attack +8; Grapple +11
Attack: Stinging vines +6 melee
Full Attack: Stinging vines +6 melee
Damage: Stinging vines 1d4 and poison
Special Attacks/Actions: Stinging vines, poison, constitution drain
Abilities: Str 10, Dex 10, Con 20, Int -, Wis 10, Cha 2
Special Qualities: bonegrowth, fire resistance 10, energy flash, plant traits
Feats: -
Skills: -
Advancement: 12-16 HD (Huge); 17-32 HD (Gargantuan); 33+ HD (Colossal)
Climate/Terrain: Warm marsh
Organization: Solitary or grove (2-8)
Treasure: 1/10 coins, 50% goods, 50% items

Source: Dragon #280
Dragon Compendium Vol. 1

The bonetree is a particularly horrible form of carnivorous plant that subsists on the various minerals found in bones. Like the other plants in the region, it draws its sustenance from the ambient radiation in the valley. It has also developed an efficient method of extracting additional nourishment from prey, both living and dead, allowing it to grow much larger than the other plants of the region.

A bonetree is a swamp-dwelling plant. It is similar to a mangrove plant in that its trunk is bulbous and lumpy and its thick nest of roots is mostly above ground. Dozens of spindly branches grow out of the top of the trunk, but its sides are barren save for hundreds of knots and jagged holes the size of an apple. The tree's bark is pale brown and its branches are leafless. For a short period of time after feeding, a bonetree can grow thick bony plates and spurs over its body to aid it in attack and defense.

A typical bonetree is 25 feet tall. Although its growth slows after reaching this height, a bonetree continues to grow its entire life. A well fed bonetree can live for hundreds of years and reach heights of 100 feet or more.