Porcupine Cactus (CR 1)

Small Plant
Alignment: Always neutral
Initiative: -5 (Dex); Senses: low-light vision

AC: 14 (+1 size, -2 Dex, +5 natural), touch 9, flat-footed 13
Hit Dice: 2d8+4 (13 hp)
Fort +5, Ref -2, Will -4
Speed: 0 ft.
Space: 5 ft./5 ft.
Base Attack +1; Grapple -4
Attack: -
Full Attack: -
Damage: -
Special Attacks/Actions: Detonate, thorns
Abilities: Str -, Dex 7, Con 15, Int -, Wis 2, Cha 1
Special Qualities: plant traits
Feats: -
Skills: -
Advancement: 3-6 HD (Small)
Climate/Terrain: Warm deserts
Organization: Solitary or patch (4-24)
Treasure/Possessions: None

Source: Sandstorm

Detonate (Ex): Merely touching a turgid porcupine cactus causes it to explode violently. The detonation can be triggered by a strong wind (over 20 mph), a sonic spell or effect that produces vibration, a moderate shaking of the ground (such as might be produced by a tunneling ashworm or the footsteps of a giant), or any amount of damage dealt to a cactus. An exploding cactus deals 2d6 points of slashing and piercing damage to all creatures within a 10-foot radius. A DC 13 Reflex save reduces the damage to half. The save DC is Constitution-based.

Although the damage from a single porcupine cactus is not usually enough to kill a creature, the explosion causes any other turgid cacti within 10 feet to explode as well. Usually an entire patch goes up at once. The resulting area of spiny flesh leaves behind the equivalent of a field of caltrops for 24 hours after the explosion. New cacti begin to sprout after that time and reach full size in a week.

Thorns (Ex): A porcupine cactus's thorns tear at any creature that touches it, dealing 1d4 points of piercing damage. Creatures that strike a porcupine cactus with natural attacks or unarmed strikes, or that try to grapple the cactus (presumably to pull it out of the ground), are subject to this damage, but creatures striking with melee weapons are not. A creature that is pushed into or falls onto a plant also takes damage from its thorns.

Porcupine cacti do not attack but simply wait for something to wander into them. Their wickedly sharp thorns protect them from damage when they are not ready to scatter seeds.

These plants are easy to avoid if someone knows what to look for. A DC 10 Knowledge (nature) check suffices to recognize the telltale circle of a porcupine cactus patch. However, creatures that are running or charging are not entitled to a check.