<1>

FREQUENCY: Common
FREQUENCY: Rare ([Tropical Saltwater Surface])
FREQUENCY: Common ([Tropical Saltwater Depths])

NO. APPEARING: 3-12
ARMOR CLASS: 6
MOVE: Nil
HIT DICE: 2-4
% IN LAIR: 100%
TREASURE TYPE: J-N, Q, C (magic only)
NO. OF ATTACKS: 1 ~ 16 (HD 2 - 3) | 15 (HD 4)
DAMAGE/ATTACK: Special
SPECIAL ATTACKS: Constriction
SPECIAL DEFENSES: Nil
INTELLIGENCE: Animal
ALIGNMENT: Neutral
SIZE: S
LEVEL/X.P. VALUE: II | 35+ 3

Strangle weed is an intelligent kelp found in relatively warm sea water.
A bed of this carnivorous plant is indistinguishable from normal seaweed.
The plant grows in an oval with 3-12 fronds in a patch of 3-12 square feet.
The fronds vary from 7’to 12’ long, and any creature within grasp of 1 or
more fronds will be attacked. A hit by the strangle weed indicates the
victim is entwined by the attacking frond. Each frond has a strength of 4-16
points. A victim compares its strength against the frond or fronds which
have entwined it. The difference in the victim’s favor is its chance of
escaping, i.e., 1 equals 10%, 2 is 20%. etc. A negative difference, a
balance in favor of the weed, indicates the victim has taken that number
of points of crushing damage, i.e. a victim‘s strength of 18 compared to the
3 fronds holding it, 30, so the strangle weeds inflict 12 points of damage on
their prey. Any creature entwined strikes at -2 on its “to hit” rolls. Treasure
is found beneath the sand of the bed of the strangle weed -- left by former
victims.

<1: actually, i don't think that's the one (Sargassum muticum). wiki Sargassum>