OK, breaking them down one at a time.
Razorvine: this creeper/ivy is harmless to anyone that doesn't touch it. Fall into a patch, you can lose limbs or bleed to death. Not intelligent, immobile, does not eat prey.
tri-flower frond: you get close to it, it launches its tendrils out at you; the first one puts you to sleep, the second dissolves you with acid, and the third sucks the bodily fluids out of the victim. Not intelligent, immobile.
hangman tree: tree has sinewy, ropey vines that strangle prey and lift it into the acid-filled barrel of the trunk. slightly intelligent, slightly mobile.
forester's bane: huge shrub; tough outer leaves trap creature while inner saw-leaves work like a blender. not intelligent, immobile, presumably deceased prey is slowly digested.
vampire rose: white rose bush with thorny stalks that drain blood. Emits a hypnotic fragrance to keep prey still. not intelligent, is mobile.
Explodestool: mushrooms that explode like firecrackers when touched, injuring and deafening nearby creatures. not intelligent, immobile, does not eat prey.
giant sundew: mound of tarry ropey hairs lashes out with sticky acidic tendrils which slow a character down and can block its nose and mouth to suffocate. semi-intelligent, semi-mobile.
giant venus fly-trap: flytrap large enough to swallow a human, with up to 8 jaws, drowns or dissolves prey with acid. Barely intelligent, immobile.
vampire cactus: cactus has a dozen barbed needles that drain blood. not intelligent, immobile.
strangle vine (Mystara): we can cut this one; there is no significant difference from assassin vines.
archer bush: wild bramble bush shoots a spray of thorns, exterior mouth devours downed prey. Not intelligent?, mobile.
black willow: evil tree likes eat humanoids, attacks with whiplike branches. Causes tired creatures to go to sleep, which the willow can pick up and put inside its body cavity to digest them quickly with acid. intelligent, barely mobile.
bohun tree: massive evil tree with fruit that can put creatures to sleep or suffocate, and is poisonous if eaten. Can fire thorns like arrows, and roots can hold creatures so that thorns hit better. intelligent, immobile.
boring grass: grass made of hard corkscrew blades that digs aggressively into material touching it, coated in paralytic poison. Presumably, the grass feeds on the remains. Not intelligent, immobile.
choke creeper: enormous 25-HD vine with numerous creepers that strangle and constrict. Not intelligent, slightly mobile (basically, the big daddy of the assassin vine).
grab grass: patch of tall grass wraps around victims and strangles them, feeding on the remains as they decompose. not intelligent, immobile.
jupiter bloodsucker: big leafy plant that can hold a victim with one leaf, smother it with another, and drain blood as it holds the victim. Not intelligent?, somewhat mobile.
mantrap: relative of the venus flytrap attracts prey by fascinating pollen, which voluntarily climb into its leaf, trapping the character and dealing acid damage. Not intelligent, immobile.
giant pitcher plant: giant green vase-shaped plant filled with water and acid grabs prey with a whiplike organ, dropping prey into the mixture, which either drowns or dissolves. not intelligent, immobile.
retch plant: palm tree drops coconut sized fruits that burst, leaking a fluid that causes creatures to vomit: fruit's odor is strong and attracts other monsters. Not intelligent, immobile, does not eat prey.
singing tree: tree's lovely voice compels creatures to approach, drops leaves on creature which drains blood through tubes connected to tree. Barely intelligent, immobile.
twilight bloom: tall trunked-plant with no branches and fern-like foliage on top. Bell-like purple flowers on the plant drop poison on victims, whose decomposing remains feed the plant. Not intelligent, immobile.
Witherweed: many fronds attack, dealing Dex damage by touch feeding on the ability drain. not intelligent, immobile, does not eat prey.
zombie plant: shrub can psionically attract victims to eat its berries, which cause Int drain and make them slaves of the plant. semi-intelligent, immobile, does not eat prey.
amber lotus flower: golden water lilies spray cloud of pollen that puts creature to sleep. ALF does not kill victim, but other plant creatures kill it and all benefit from fertilization of soil. Not intelligent, immobile.
Bloodflower: bushes contain white flowers that become deep red as the plant feeds, narcotic perfume puts creatures to sleep, leaves drain blood. Not intelligent, immobile.
Burnflower: patch of grey-green vines with closed flowers that absorb sunlight, releasing it in a deadly heat ray. Not intelligent, immobile, does not eat prey.
dew fronds: a quickly-growing plant with large barbed fronds that cut into a creature and stick in to drain blood. Not intelligent, immobile.
firethorn: squat, broad rose bushes with thorny scarlet blooms. Scent causes confusion, and touching the thorns causes fire damage and deadly poison. Not intelligent, immobile, does not eat prey.
killer tree: ordinary-looking tree with branch-tentacles that can grab creatures to drag to its mouth to bite. barely intelligent, immobile.
pilfer vine: large mass of tangled and twisted creeper vines that steals shiny objects, can defend itself with its vines by constricting/strangling. semi-intelligent, somewhat mobile, does not eat prey.
Sashalus: mushroom-like fungus that fires poisonous spines (effect variable, including unconsciousness, confusion, or nausea) and eats downed or helpless prey by dissolving it with acid. Semi-intelligent, somewhat mobile.
sirenflower: large fungus has big leaves that close and crush on a creature while dissolving it. foes are drawn in using scents and lights. Not intelligent, immobile.
somnastis plant: this large rosebud exudes an inhaled poison that puts creatures to sleep, allowing the plant to place the victim on its acidic flower bud. Not intelligent, immobile
strangling vines (Athas): like the Mystara version, this one is simply too similar to an assassin vine.
sword grass: plant has a number of huge blades of grass, which slice through anyone walking through the grass. Feeds on the blood and decaying bodies of victims. Not intelligent, immobile.
thornslinger: this low-lying blossom-covered plant fire a volley of thorns at anything that moves. Anything touching the plant is caught by its powerful adhesive, and is also subject to its digestive acid. not intelligent, immobile.
vampire moss: netlike mass of pale green moss hangs from trees, drawing life energy from nearby creatures (physical contact not necessary!); on a failed Fort save creature loses 1 hp per round. Not intelligent, immobile.