Pseudobulb
Encyclopedia
The pseudobulb is a storage organ
Storage organ
A storage organ is a part of a plant specifically modified for storage of energy or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have an underground storage organ are called geophytes in the Raunkiær plant life-form...

 derived from the part of a stem between two leaf nodes.

It applies to the orchid family (Orchidaceae
Orchidaceae
The Orchidaceae, commonly referred to as the orchid family, is a morphologically diverse and widespread family of monocots in the order Asparagales. Along with the Asteraceae, it is one of the two largest families of flowering plants, with between 21,950 and 26,049 currently accepted species,...

), specifically certain groups of epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

 orchids, and may be single or composed of several internodes with evergreen or deciduous leaves along its length.

In some species, it is hardly swollen at all and looks like a normal stem with many leaves while at the other extreme, some genera such as Bulbophyllum
Bulbophyllum
Bulbophyllum is the largest genus in the orchid family Orchidaceae. With more than 2,000 species, it is also one of the largest genera of flowering plants, exceeded only by Astragalus...

have single, spherical pseudobulbs with one (or two) leafs at the apex of each.

Whether cane-like (with many joints) or spherical (with one or few joints), they are all produced from a long lived creeping stem called a rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...

 which may itself be climbing or pendulous.

The pseudobulbs are themselves relatively short lived (1–5 years), but are continually produced from the growing tip of the rhizome.

The other growth habit used by tropical epiphytic
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...

 orchids is known as monopodial
Monopodial
Vascular plants with monopodial growth habits grow upward from a single point. They add leaves to the apex each year and the stem grows longer accordingly...

.
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