Abyssinian shrivelfig
Potion ingredient, needs to be peeled. (CS15)

Alihotsy
Eating the leaves causes hysteria (FB).

bouncing bulbs
repotted during Herbology class, one wriggled free from Harry's grasp and banged him in the face (GF18)

bubotubors
Bubotubors are disgusting-looking plants which exude a yellowish pus that smells like petrol. Bubotubor pus is an excellent cure for acne. (GF13)

Devil's Snare
Devil's Snare is a magical plant which loves the dark and damp. It is composed of a mass of soft, springy tendrils and vines and is semi-sentient. When a person gets too close to Devil's Snare, it uses its creepers and tendrils to ensnare them, binding their arms and legs and eventually choking them. The harder a person struggles against Devil's Snare, the more faster and more tightly it binds them; if they relax, it will not kill them as quickly. Devil's Snare shrinks away from fire, so a well placed flame spell such as Bluebell Flames will drive it away from its victims.

First year students at Hogwarts learn about Devil's Snare in Herbology classes. 

Harry, Ron, and Hermione encountered Devil's Snare in the chambers under the castle which hid the Philosopher's Stone (SS16): 

"Devil's Snare, Devil's Snare... what did Professor Sprout say?-- it likes the dark and the damp..."
"So light a fire!" Harry choked.
"Yes -- of course -- but there's no wood!" Hermione cried, wringing her hands.
"HAVE YOU GONE MAD?" Ron bellowed. "ARE YOU A WITCH OR NOT?"
"Oh, right!" said Hermione, and she whipped out her wand, waved it, muttered something, and sent a jet of the same bluebell flames she had used on Snape at the plant. In a matter of seconds, the two boys felt it loosening its grip as it cringed away from the light and warmth. Wriggling and flailing, it unraveled itself from their bodies, and they were able to pull free.
"Lucky you pay attention in Herbology, Hermione," said Harry as he joined her by the wall, wiping sweat off his face.
"Yeah," said Ron, "and lucky Harry doesn't lose his head in a crisis-- 'there's no wood,' honestly."

dittany
One of the plants found in One Thousand Magical Herbs and Fungi (SS14)

Flutterby Bush
This kind of bush quivers and shakes. The Flutterby bushes needed pruning in herbology class (GF20)
"flutterby" is sometimes used in English as a play on the word "butterfly"

gillyweed
Native to the Mediterranean, this water plant, when eaten, gives a person gills to breathe underwater and gives them webbed hands and feet for swimming. It looks like slimy, grayish-green rat tails. The duration of the gillyweed effect is approximately one hour. Snape keeps Gillyweed in his private stores; it is not available to the students (GF26)

leaping toadstools
The second year Herbology classes worked with these.(CS14)

Mandrake(Mandragora)
The Mandrake root is a powerful restorative. It forms an essential part of most antidotes, including one for Petrification (CS6) The Mandrake Restorative Draft returns people who are transfigured or cursed to their original state. Mandrake seedlings are tufty little plants, purplish green in color (CS6) with what look like tiny babies growing where the roots would be. These creatures grow and develop over the course of several months until they mature and can be harvested and used for potions. The cry of the Mandrake is fatal to humans, so special care must be taken  when growing them. Even as a baby, the Mandrake's howls can knock a person out for a couple of hours.
The Dugbog is particularly fond of eating Mandrakes (FB).

puffapod
fat pink pods with seeds that burst into flower if dropped (PA8)

umbrella-sized flowers
hanging from the ceiling of greenhouse 3 (CS6)

venomous tentacula
spiky, dark red - teething, reaches out vines toward people (CS6)

Whomping Willow
large, violent tree that attacks anyone who gets too close (CS, PA)