Vascular cambium

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The vascular cambium is located between the xylem and the phloem in the stem and root of a vascular plant, and is the source of both the secondary xylem growth (inwards, towards the pith) and the secondary phloem growth (outwards). It is a cylinder of unspecialized meristem cells that divide to give new cells which then specialize to form secondary vascular tissues.

Vascular cambia are found in dicots and gymnosperms but not monocots, which usually lack secondary growth. A few leaf types also have a vascular cambium.[1]

For successful grafting, the vascular cambia of the rootstock and scion must be aligned so they can grow together. In wood, the vascular cambium is the obvious line separating the bark and wood.[2]

The cambium present between primary xylem and primary phloem is called intrafasicular cambium. At the time of secondary growth, cells of meduallary rays, in a line with intrafasicular cambium become meristematic and form interfasicular cambium. The intrafascicular and interfascicular cambiums, therefore, represent a continuous ring which bisects the primary xylem and primary phloem and is known as cambium ring. The vascular cambium then produces secondary xylem on the inside of the ring, and secondary phloem on the outside, pushing the primary xylem and phloem apart.

The vascular cambium usually consists of two types of cells:

  • Fusiform initials (tall cells, axially oriented)
  • Ray initials (almost isodiametric cells - smaller and round to angular in shape)

Synonyms[edit]

  • Wood cambium
  • Main cambium
  • Bifacial cambium

See also[edit]

References[edit]

  1. ^ Ewers, F.W. 1982. Secondary growth in needle leaves of Pinus longaeva (bristlecone pine) and other conifers: Quantitative data. American Journal of Botany 69: 1552-1559. [1]
  2. ^ Capon, Brian (2005). Botany for Gardeners (2nd ed.). Portland, OR: Timber Publishing. p. 64. ISBN 0-88192-655-8. 

External links[edit]