Cleon
Legend
I'm inclined to stick with the plant type. To better fit it, we could say the tips of the reeds simply resemble snake heads.
Alternately, I could see these as aberrations with plantlike traits, perhaps created by the yuan-ti.
I prefer Plant for them too.
Getting some inspiration from the Hydra, Medium Viper and Tendriculos, hows about something like this:
Snake Grass
Medium Plant
Hit Dice: 2d8+6 (15 hp)
Attack: Bite +1 melee (1 plus poison)
Full Attack: 1+ bites +1 melee (1 plus poison)
Special Attacks: Poison, sprout heads
Special Defenses: All-around vision, darkvision 60 ft., low-light vision, plant traits, scent
Abilities: Str 10, Dex 10, Con 16, Int --, Wis 8, Cha 3?
Feats: Combat Reflexes (B), Weapon Finesse (B) ?