假鳞茎是两片叶子的结处产生的变态茎，是水和养分的贮藏器官。

假鳞茎是兰科植物特有的器官，而且主要见于附生兰，可能是由单个或多个常绿叶或落叶的节间构成。

一些兰花的假鳞茎看起来很平常，跟其他长满叶子的植物茎没什幺两样，而另外一些兰花，如石豆兰属（Bulbophyllum）却有体积很大的球形假鳞茎，而且在每1片或2片叶子的基部都有假鳞茎。

无论是多关节的假鳞茎，还是球形的假鳞茎，都是从常年生长的、被称为根状茎的匍匐茎长出的，而根状茎可能是攀缘性的，也可能是悬垂的。

虽然假鳞茎的寿命只有1－5年，根状茎的生长锥会源源不断的产生假鳞茎。

The pseudobulb is a storage organ found in many epiphytic and terrestrial sympodial orchids. It is derived from a thickening of the part of a stem between leaf nodes and may be composed of just one internode or several, termed heteroblastic and homoblastic respectively. All leaves and inflorescences usually arise from this structure. Pseudobulbs formed from a single internode produce the leaves and inflorescence from the top, while those that are formed from several internodes can possess leaves along its length. The modified sheath leaves that appear at the base of a pseudobulb and often enfold all or part of it are usually dry and papery, though in some orchids the sheaths bear leaf blades and the leaves at the pseudobulb's apex are reduced to scales.