These members of the Prayer Plant family Marantaceae have very detailed markings on their leaves, They do put their leaves into prayer position in the evening, exposing the beautiful purple underside, and then flatten out again in the morning. These aren't as needy as some others in this group and will be happy enough with your average humidity in your home, that being said, if it is looking a little sad due to drying heater induced air in winter, move it to somewhere warm, but higher humidity, like a bathroom or kitchen. these guys like moderate, indirect light. Keep evenly moist in the warmer months and allow to dry slightly between watering during winter. Apply liquid fertilizer monthly if you can see new growth, usually during the warmer months.