It attracts prey with a sweet aroma, then downs it with thorny whips hidden in its arms.
(From Bulbapedia)Roserade is a bipedal Pokémon with an appearance that incorporates features of roses and masquerade attire. It has hair made of white rose petals, and a leafy, green cape with a yellow, collar-like bangle on its neck. The cape pattern reaches toward the back of its head, in spiky, sepal-like extensions on the hair. A male will have a shorter cape than a female. It has a dark-green mask over its red, yellow-lidded eyes. The lower portion of its face is light green, and it holds a bouquet in each hand. It has a red in its right hand and blue in its left. Its limbs and underside are light green. Its feet end with yellow tips.
Roserade lures prey with a sweet aroma. The more toxic its poison, the sweeter its aroma becomes. Each hand has different toxins, but both hands can jab with near-deadly power. It attacks with a dancer-like elegance, and uses hidden whips covered with poisonous thorns.
Relic Roserade was the first Relic Pokemon to be designed
Roserade appears to be based on a combination of a bouquet of roses, and a mysterious patron of a masquerade ball, in which masks would be worn to hide the identity of the participants. Its mask, cape and the mention of its 'movements of a dancer' in its Pokédex entry seem to confirm this.
It is also possible that, instead of roses, its design was based on hellebores, a genus in which many species are poisonous and deceptively similar to roses, tying in once again to the theme of disguises. Finally, Roserade's humanoid design, connection to flowers, and one of its Egg Groups suggest that it is also based on fairies.
Roserade may be a combination of rose and masquerade (due to the appearance of wearing a mask).