Grave's Tear

Grave's Tear is a poisonous plant that grows on graves because its roots intertwine with the decomposing bodies of animal corpses. If the bodies are covered in seeds before being buried, this plant will grow from the grave upwards and cover the ground of the grave in a sea of beautiful blue little flowers with purple, black, and white dots covering the little petals. Because of this, it is custom to bury the dead with a handful of seeds of Grave's Tear in some areas, in particular among the Verdantien Fae, to decorate the graves of their fallen.
Grave's Tear is an extraordinarily resilient plant. It can thrive for weeks without sunlight as it finds its way from darkness toward the sun, and it can use the blood in the decomposing body as a replacement for water, and draws nutrients from the body it's growing on rather than the soil around. In fact, Grave's Tear has never been found not growing in soil without a carcass and it remains unclear whether or not that would be possible.
Most notably, there is a variation of Grave's Tear that has red petals, a special breed that is found in the homes (or rather cave systems) of Necromancers who, according to legend and their own boasting at least, water their plants with blood. Some academic attempts to grow the plant on a mouse carcass and water it with blood have not resulted in the same discoloration, however, and there is some dispute about whether the red form of Grave's Tear exists and if it does, how it can be reproduced in different environments. Of course, Necromancers keep their mouth shut beyond their gloating, and since no outsiders get to enter the secret halls and laboratories that Necromancers use, it remains unclear if that plant exists in different colors at all...