Assassin Flower

False Appearance. While the assassin flower remains motionless, it is indistinguishable from a normal plant, without a successful DC 20 Wisdom (Perception) check. When the flower above ground is plucked or disturbed, the plant emerges from the ground and attacks. A successful DC 15 Dexterity save is required to prevent a surprise round. 

Constrict. Melee Weapon Attack: +4 to hit, reach 20 ft., one creature. Hit: The target takes 6 (1d6 + 2) bludgeoning damage, and it is grappled (escape DC 14). Until this grapple ends, the target is restrained, and it takes 10 (3d6) poison damage at the start of each of its turns. The roots can constrict only one target at a time.

Entangling Roots. The assassin flower can animate normal plants and flowers on the ground in a 15-foot square within 30 feet of it. These plants turn the ground in that area into difficult terrain. A creature in that area when the effect begins must succeed on a DC 13 Strength saving throw or be restrained by entangling vines and roots. A creature restrained by the plants can use its action to make a DC 13 Strength (Athletics) check, freeing itself on a successful check. The effect ends after 1 minute or when the assassin flower dies or uses Entangling Roots again.