botany Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...

, a pseudobulb is a storage organ found in many

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

and terrestrial

sympodial In botany, sympodial growth is a bifurcating branching pattern where one branch develops more strongly than the other, resulting in the stronger branches forming the primary shoot and the weaker branches appearing laterally. A sympodium, als ...

orchid Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Orchids are cosmopolitan plants that are found in almost every habitat on Eart ...

s. It is derived from a thickening of the part of a stem between

leaf A leaf (: leaves) is a principal appendage of the plant stem, stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leav ...

nodes and may be composed of just one internode or several, termed ''heteroblastic'' and ''homoblastic'' respectively. All leaves and

inflorescence In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...

s 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.Hew, C.S., and J.W.H. Yong. 2004
The Physiology of Tropical Orchids in Relation to the Industry.
Singapore: World Scientific Publishing Co. pp. 13-15. 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.Dressler, R.L. 1993. Phylogeny and Classification of the Orchid Family. Portland, Oregon: Dioscorides Press. p. 19. 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'' is a genus of mostly Epiphyte, epiphytic and Lithophyte, lithophytic orchids in the Family (biology), family Orchidaceae. It is the largest genus in the orchid family and one of the List of the largest genera of flowering plants, ...

'' have single, spherical pseudobulbs with one (or two) leaves 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 In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and Shoot (botany), shoots from its Node (botany), nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from ...

which may itself be climbing or pendulous. The pseudobulbs are relatively short lived (1–5 years), but are continually produced from the growing tip of the rhizome and may persist for years after its last leaves senesce. The term pseudobulb is used to distinguish the above-ground storage organ from other storage organs derived from stems that were underground, namely corms or true bulbs, a combination of an underground stem and storage leaves. Strictly speaking, there is no clear distinction between the pseudobulb and corm structures.

References

External links

*{{Commons-inline, Pseudobulbus (Orchidaceae), Pseudobulb Orchid morphology Plant stem morphology