Mirth Leaf

Mirth Leaf is a plant-type entity encountered in Oxygen Not Included that produces a persistent floral scent germ in nearby gases while blooming. It functions as a biological source of the Floral Scent germ and interacts with atmosphere, duplicant stress, and other germ/atmosphere mechanics in predictable ways. Mirth Leaf appears in habitats where Bristle Blossoms and Buddy Buds are found and contributes to the local airborne germ load when it is in bloom.

The Floral Scent germ created by Mirth Leaf has a defined temperature tolerance of -10°C to 100°C and persists across pressures from 0 kg to 1000 kg. Its infection checks are binary: exposure results in acquisition according to the game's infection mechanics without gradation from immune-boosting traits. When a duplicant becomes affected, duplicated effects depend on traits: duplicants with the Allergic trait suffer +15% stress per cycle and +10 Sneeziness, while other duplicants gain -5% stress per cycle from the scent. The typical symptom duration is 0.1 cycle per exposure event.

Floral Scent germs are disinfected by multiple modalities: contact with solid surfaces, presence in gas or liquid disinfectants, and exposure to oxygen are all listed as disinfecting conditions; however, Floral Scent dies off significantly faster in Polluted Oxygen than in clean Oxygen, effectively making Polluted Oxygen a stronger disinfectant for this germ. Polluted oxygen produced by slime in an atmosphere that also contains Floral Scent will not carry slimelung germs; instead it carries Floral Scent germs, allowing combinations of slime, Buddy Bud plants, and deodorizer to generate oxygen atmospheres free of slimelung.

Allergic reactions caused by exposure to Floral Scent can be prevented or treated with Allergy Medication produced at the Apothecary. Allergy Medication grants prevention for 720 seconds. The same medicine cures active floral-scent infections. Bleachstone can also mitigate Floral Scent germ presence by disinfecting affected tiles.

Practical notes for colony management:

• Place Mirth Leaf away from high-traffic areas if you have many Allergic duplicants; its scent benefits non-allergic duplicants but harms allergic ones.
• Use Polluted Oxygen, deodorizer, or bleachstone in air handling to accelerate Floral Scent die-off when necessary.
• Apothecary-produced Allergy Medication is the reliable countermeasure for allergic duplicants and can be used proactively to prevent reactions during high-exposure periods.
• Be aware of the plant’s bloom behavior: it only spreads Floral Scent while blooming, so timing and placement can control when germ production occurs.
• When designing atmospheric loops or slime-based oxygen production, account for Floral Scent replacing slimelung in polluted oxygen in mixed setups.