As a witch, Melinoë must use all the matter of reagents to give her the power to defeat Chronos. Many flowers will enter Hecate's Cauldron in Hades 2, but one of the flowers that you only need a few of is Myrtle.
Hades II – The Risen Fleet
Where is this white-petaled flower, and do you need a lot of it? Let's discuss the details.
Myrtle is a randomly spawning flower in the Mourning Fields, the third location of Hades 2. These flowers aren’t uncommon and don’t require any additional tools to collect. However, at this point, there are no other ways to collect them other than hoping the map is kind to you. Don’t be surprised if, due to how large the sections of the Mourning Fields are, you don’t get a single Myrtle per run.
This is by far the rarest handpicked flower of all – much rarer than Moly or Lotus – because the Mourning Fields is such a tight and compact location. You only get three or four chances to spawn the flower at all. If you've done the Reagent Sensing Incantation at the Cauldron, you'll be led to a Myrtle once you've cleared the room of all locked rewards. This is the best way to guarantee that you'll find all of the Mourning Field flowers during your run.