S'gagerat is a type of plant native to the planet Vulcan. They were predatory plants known to exist in Vulcan's Forge. They had long tendrils which extended beneath the sand and laid there until prey approached. Afterwards, the tendrils would instantly snap around the plant's central core, where large animals such as the Sehlat would be trapped. Once the prey was within its grip, the tendrils would inject a powerful soporific into the captured 'food', which would allow for a slow digestion.
If the prey managed to escape, the S'gagerat would extend its tentacles in search for its quarry. Typically, very few survive such attacks from these deadly plants, which were known to kill Vulcans. (TOS - Vulcan's Soul novel: Exiles)