Tillandsia, commonly known as air plants, are fascinating plants that are among the easiest indoor foliage to grow. To get the best results, as with all plants, it helps to know what their native habitat is like and in the case of Tillandsia, there are two types: Xeric and Mesic.
Xeric Air Plants
Xeric conditions occur in deserts and mountain areas where the humidity is low and the tree cover is sparse. These areas are prone to drought and fluctuating temperatures. Often growing on rocks at higher altitudes, xeric air plants are more adaptable to the drier and brighter conditions. You will notice that xeric air plants are greyer and fuzzier than mesic air plants which are greener and smoother. These fuzzy bits are scales called trichomes and are a truly amazing feature of the plant. They regulate the amount and the timing of water allowed into the leaf and can protect the plant from sunburn. Common xeric air plant species are Tillandsia tectorum, T. xerographica, T. caput-medusae, and T. ionantha.
Mesic Air Plants
Mesic environments, such as rainforest canopies of Central and South America, stay moderately wet and cool for most of the year, so Tillandsia originating in mesic climates like more humidity and less direct light in general. You will want to water your mesic air plants more often than your xeric ones. However, being a "wet" type air plant doesn't mean the plant enjoys staying wet, it just means it can tolerate more frequent waterings. All air plants will rot if not allowed to dry off immediately following a watering. Common mesic air plant species are Tillandsia bulbosa, T. andreana, T. brachycaulos, and T. butzii.