Structure of the Vascular Cambium
This meristem, in the anatomical sense of the term usually includes two histologically distinct kinds of cells:
i) Fusiform Initials,
ii) Ray Initials
These are usually axially elongated cells along with tapered ends. The mean length of fusiform cells varies, among taxa and within an individual plant. It tends to increase with the age of the plant. These cells are shaped somewhat similar to flat shoe laces. It would be easy to assume that they have about 8 faces but a study of Pinus sylvestris has shown that 8 sides are minimum; they can often have up to 32 faces with an average of 18; they have 14 contact faces with other such cells.
They are smaller than fusiform initials and are nearly isodiametric (equal dimensions, small slides) or only about two or three times as tall as wide.