Plant is a special elemental attribute only explicitly found in Castlevania: Circle of the Moon. However, in other games, plants are used as forms of offense and in the Metroidvania titles they are associated with strike.
In Circle of the Moon, when the Diana and Mandragora cards are used together Nathan will unleash three arrays of rose petals in three different directions when his whip is swung. Combining the Mandragora card with the Apollo will let Nathan throw an explosive rose.
In Aria of Sorrow, the Mandragora soul will let Soma bring forth a Mandragora, whose scream will damage enemies. The dryad soul lets Soma toss seeds that will, if they hit an enemy, sprout a dryad that drains their life.
In Dawn of Sorrow, the Une soul will let Soma throw seeds that sprout Unes.
In Circle of the Moon, combining Mercury with Mandragora will grant Nathan a thorn whip, which will launch rose petals from its tip when it is swung. Mars and Mandragora together let Nathan wield a rose sword that also unleashes rose petals.
In Circle of the Moon, An owl familiar can be summoned if the Saturn and Mandragora cards are used together. This familiar will fly overhead enemies and drop green globs on them. The Mandragora itself can be summoned by combining its card with Uranus and upon summoning it unleashes a series of sonic blasts.
In Aria of Sorrow, Soma, with the Alura Une soul, can summon a Alura Une behind him to heal 10 HP every second while the summon is maintained.
In Dawn of Sorrow, the Alura Une soul will Soma summon a Alura Une, which will attack enemies with its vines. With the Corpseweed soul Soma can summon a familiar of it that spits poisonous globs.
In Circle of the Moon, combining the Venus card with the Mandragora card will result in Nathan gaining a 25% increase in his luck when his magic is activated. Nathan can slowly regenerate his health when idle if the Jupiter and Mandragora cards are used together. Combining Neptune with Mandragora will let Nathan gain health from plant attacks. Combining Pluto with Mandragora grants Nathan a 20% boost to experience points gained when an enemy is killed.
In Dawn of Sorrow, the Treant soul will grant Soma increased MP recovery when equipped. The Wakwak Tree soul will increase Soma's CON while decreasing his STR.
Castlevania II: Simon's Quest featured Killer Plants, which spat fireballs.
Bloodlines featured another version of the Stone Rose and it featured the Deadly Vine and Circle Weed enemies.
Symphony of the Night featured the Venus Weed enemies that became Alura Une in later titles. Corpseweed is feature as well, growing from Thornweed. Stone Roses are also featured in this game, spitting petrifying seeds and releasing deadly powder. The Saturn version of the game featured Hitotorisou, which snapped if the player got too close and Jinnunja, which throw its own fruit.
Circle of the Moon featured Forest Armor, who used vines to attack. It featured the Man Eater, which spat out poisonous seeds. It also feature the Aluraune, which used vines from the ground to attack. Dryads were trees that released spirits to attack Nathan.
Harmony of Dissonance featured Man Eater, which spat out petrifying seeds.
Aria of Sorrow featured Une. Dryads appear as tree women that throw explosive seeds. Alura Une attack by raising vines from the ground. Mandragora are uprooted by skeleton, which at that point it unleashes a scream that damages Soma and destroying itself.
Lament of Innocence featured Man-eating Plant, which spat out poisonous seeds. Skeleton Flowers burrow themselves at wherever Leon is located.
Dawn of Sorrow featured Une. Mandragoras perform a suicidal scream attack when they uproot themselves. Skeleton Farmers toss seeds that became Unes and Mandragoras. Corpseweeds sprout from Unes. Treants are animated trees that either try to grab or kick the player. Wakwak Tree produces Flea men from its branches. Alura Une throw seeds and raise vines from the ground.
Portrait of Ruin featured Une, Corpseweed, Treant, Maneating plant, Alura Une and Wakwak Tree.