Most dahlias stand for elegance and prosperity, but the striking black variety (really a deep burgundy) is a well-known symbol of betrayal. It's a shame its flower meaning is so negative, because it's stunning.
Burgundy (black) dahlia's are flowers that have the most negative meaning out of all the colours, as they are said to symbolise betrayal – Or they're just the perfect choice for a goth friend.
Deadly Nightshade
A highly poisonous plant (Atropa belladonna) with purple bell flowers and small black berries. A symbol of deception, danger, and death.
HYDRANGEA: Thank you for understanding, frigidity, heartlessness, heartless.
Hyacinth: The purple hyacinth is a popular symbol of sorrow and regret.
Flowers that symbolize sadness are: Lilies, Purple Hyacinth, Sowbread, Periwinkle, Mum (Chrysanthemum), Zinnia, Carnations, Forget-Me-Not, and Cyclamens.
Petunia. A flower that is not very common, Petunias display feelings of deep resentment and anger.
There are lots of colors of lilies, however, the one color that you should stay away from is orange. Orange lilies can symbolize hatred, pride, disdain, and contempt. In general, lillies are the flowers of sadness as they can also represent renewal, rebirth, and restoration of a soul.
But be sure not to give a Red dahlia. It symbolizes betrayal and dishonesty. Think of that poor Victorian gentleman presenting his lady with a bouquet of Red Dahlias.
Especially yellow Carnations. Yellow carnations symbolise rejection, disappointment and disdain. They are perfect for curses made with one of these intents in mind. Striped Carnations represents regret and rejection, so they could be perfectly used for a curse against an ex who wronged you badly.
Hyacinth. The purple hyacinth specifically, represents sorrow, regret and forgiveness.
Marigold: Grief or despair.
Tulip (yellow) - Hopeless love. Violet - Faithfulness.
Amaranthus: Hopelessness
Considering that it looks like a person whose entrails have been torn out, you might not be surprised that, in Victorian England, Amaranthus caudatus signified hopelessness and heartbreak (one of its alternative names is "love lies bleeding").
Aconite (Monkshood)
Not all flowers have good meanings and the Aconite is one of the exceptions. This pretty-looking flower actually means 'hatred' and 'be cautious'.
Cherry Plum. This flower essence helps with a sense or fear of losing control, which can be a symptom of PTSD.
Hydrangea Meanings
Victorians considered hydrangeas a negative plant and used it to represent boastfulness, bragging, or vanity. Hydrangeas became associated with boastfulness and vanity because they produce magnificent flowers, but very few seeds.
Titan arum, corpse flower
The titan arum, the first of two flowers in this list nicknamed the corpse flower, carries the unfortunate designation of being "the worst smelling flower in the world." It smells like — you guessed it — a stinking, rotting corpse.
The Flower Demon (Hana Oni?) was a demon in Kimetsu No Yaiba: A New Full Moon. She was also one of the 4 servants of the new Lowermoon 2, Haruyo. The Flower Demon's job was to gather information in the Northwest Village as Haruyo had said there was a Hashira roaming around looking for demons.
Lotus flower meaning across cultures
Because lotuses rise from the mud without stains, they are often viewed as a symbol of purity. Since they return to the murky water each evening and open their blooms at the break of day, lotus flowers are also symbols of strength, resilience, and rebirth.
Generally symbolic of love, honor, happiness wealth, romance, and beauty, the peony is traditionally given on special occasions as an expression of goodwill, best wishes, and joy.