空气凤梨是铁兰属（学名：Tillandsia）植物的通称，又名气生凤梨、空气草、铁兰花。属于凤梨科植物，是一般食用菠萝的近亲。分布于中南美洲、南美洲和北美洲南部。原生种类逾500种，种类之多是凤梨之冠。近年来不断出现人工杂交的品种，新的野生品种亦陆续被发现。

空气凤梨根部稀疏，外露在空气之中，仅能作固定植株之用。叶片上长有会吸水的细毛，叶面的鳞片状组织能够吸收雨水或吸收空气中的湿气，是真正吸收水和养分的器官。

这一亚科的物种是附生植物，以根部依附在树林或岩石上，有一些物种更可以攀附仙人掌、电线杆甚至半空中电在线。但部分物种因为生长条件特殊，只能生存在单一山谷或山区中。因为它们生长的环境范围很广，所以不同物种各有其喜爱的环境。

Tillandsia is a genus of around 730 species of evergreen, perennial flowering plants in the family Bromeliaceae, native to the forests, mountains and deserts of Central and South America, the southern United States and the West Indies. Airplant is a common name for plants in this genus. Most Tillandsia species are epiphytes – i.e. they normally grow without soil while attached to other plants. Some are aerophytes or air plants, which have no roots and grow on shifting desert soil. Generally, the thinner-leafed varieties grow in rainy areas and the thick-leafed varieties in areas more subject to drought. Most species absorb moisture and nutrients through the leaves from rain, dew, dust, decaying leaves and insect matter, aided by structures called trichomes.