The pleasant, verdant hillside disappears beneath your feet. In its place emerges a giant maw filled with sharp teeth.

Quickgrass (CR 4; XP 1,200)
N Huge plant
Init -5; Senses tremorsense 60 ft.; Perception +3
AC 17, touch 7, flat-footed 17
(+4 cover, -5 Dex, +10 natural, -2 size)
hp 45 (6d8+18)
Fort +7, Ref +4, Will +2
Defensive Abilities blind, camouflage, cover; Immune plant traits
Speed 0 ft.
Melee bite +8 (2d6+7 plus grab)
Space 15 ft. (main body); Reach 0 ft. (see slick)
Special Attacks slick, swallow whole (2d4+7 bludgeoning plus 1d6 acid, AC 12, 4 hp)
Str 21, Dex 1, Con 15, Int 2, Wis 10, Cha 6
Base Atk +4; CMB +10 (+14 grapple); CMD 15 (can’t be tripped)
Feats Skill Focus (Perception), Toughness, Weapon Focus (bite)
Skills Perception +3, Survival +6
Environment hills
Organization solitary or garden (2-10)
Treasure incidental
Special Abilities
Camouflage (Ex) Quickgrass looks like normal shrubbery when at rest. A character can recognize it for what it is with a DC 20 Survival or Knowledge (nature) check.
Cover (Ex) Since a quickgrass’s body is buried in the ground, it has cover against other creatures (+4 AC and +2 bonus on Reflex saves against attacks originating from the other side of the cover). The AC bonus is included in the statistics block.
Slick (Ex) If the quickgrass detects prey, it can rapidly fold its blades flat towards its center, creating a slick one way surface that causes all creatures within a 30 foot radius to begin sliding toward its maw. Anyone in the area must succeed on a DC 18 Reflex save (higher if on a steep slope) or slide 25 feet toward the quickgrass (provoking an attack of opportunity from the quickgrass upon entering its threatened area), landing prone. The shrubbery hiding the creature’s body is retracted at this point to prevent creatures from grabbing onto it. The save DC is Strength-based. Creatures who succeed on their saves must succeed on DC 15 Acrobatics checks each round to move in the slick area. Falling causes a creature to slide 25 feet toward the quickgrass, as above.

Quickgrass is one of the leading causes of disappearances in civilized lands. Quickgrass appears to be a patch of grass, usually growing on a gentle slope or hollow, with a leafy shrub growing at its center. Quickgrass grows in fields of ordinary grass, making detection difficult. The only way to distinguish quickgrass is by the slightly slimy quality to its blades or by walking upon it. When quickgrass is trod upon, its blades all flatten into a slick surface, and its shrubbery retracts, revealing a large and hungry mouth. Those upon it slide into the creature’s maw and are swallowed down. Then, as quickly as it attacked, the grass springs back up and the shrubbery returns, revealing nothing of what took place.

On Porphyra
Quickgrass are a common enough pest in the Fourlands and Parl Pardesh that regular burning of the plains are undertaken if enough are detected.