The formation of secondary tissues is characteristic of most woody plants, to whatever class they belong.
The order is easily distinguished by the hard, dry, woody texture of the leaves and the dehiscent fruits.
Secondly, the histology of fossil plants, particularly woody plants of the carboniferous period, has been placed on a sound basis, assimilated with general histological doctrine, and has considerably enlarged our conceptions of plant anatomy as a whole, though again.
Irregularity of cambium occurs in various families of woody dicotyledonous plants, mostly among the woody climbers, known as lianes, characteristic of tropical and sub-tropical forests.
Turning now to outgrowths of a woody nature, the well-known burrs or knaurs, so common on elms and other trees are cases in point.