I would like to have a plant in my bathroom, that can absorb the humidity when I shower, so that no attention to irrigation would be required. The bathroom however doesn't have direct sunlight.
The only plants that can live and grow without being directly watered are called epiphytes. Some common ones grown as houseplants include:
- Ferns, especially Staghorn ferns
- Bromeliads, especially Spanish moss,
- Jungle cacti, like Rhipsalis
- Orchids, (Cattleya and Cymbidium come to mind)
All of these plants, however, require light, preferably right filtered light out of direct sun. This means that they will suffer and decline in even a normally bright bathroom, when all the other conditions are met. You need supplemental lighting, especially as you don't have windows. A 150-300 watt led grow light at a 3-4' range should work. These plants are all equatorial, so daylength (how long you need to leave the light on) will be about 12 hours per day.
Watering shouldn't be necessary, but they require high humidity at all times, and a daily/twice daily misting of the stems, root area, and leaves is beneficial. The temperature should stay over 65 degrees F. at all times, but if it goes over 80, the high humidity is even more important.
About pothos. It is a very resilient plant, and can take a lot, but it needs to be watered regularly, as it grows in soil as other plants do. Unfortunately, there is no plant that will be entirely independent with watering, so if you really can't pay attention to your plant, then do as Bamboo suggests, and get a fake plant.
If there is no natural light of any description in your bathroom, I'm afraid that means a plastic plant - all living plants need light, even shade loving plants, so unless you substitute a growlight in your bathroom and leave it on for the required number of hours, fake plant it is. Which also, of course, won't need watering...
(merging @Bamboo's, @J-Musser's and @treeNinja's answers to a community wiki)
Plants suitable for high humidity:
- UV light source should be timed.
- Water-proof LED
Placing suggestions: The plants should be placed within close proximity to the UV source, to avoid using high power lighting.
- On top of a cupboard.
- A small shelf hanging from the ceiling.
- Between the sink and the mirror.
- On the edge of the bath next to the wall are interesting locations.
- Plastic plant
Would there be indirect light from a window or would the only light be from a bathroom light fixture? Some light is important.
Pothos come to mind because they can handle higher humidity and do not require a lot of light. The an survive in a small pot with some dirt but grow quite long and large. Look for dark rich green leaves.
Orchids also love humidity and warmer temperatures.