Fill in the blanks: In older trees, the greater part of (a) is dark brown due to deposition of tannins, resins, oil, guns, aromatic substances and essential oil in the central layers of the stem. These substances make it hard durable and resistant to the attacks of microorganisms and insects. This region is called (b)

Question

Fill in the blanks: In older trees, the greater part of (a) is dark brown due to deposition of tannins, resins, oil, guns, aromatic substances and essential oil in the central layers of the stem. These substances make it hard durable and resistant to the attacks of microorganisms and insects. This region is called (b) (A) (a)-secondary xylem, (b)-sapwood (B) (a)-secondary xylem, (b)-heartwood (C) (a)-secondary phloem, (b)-softwood (D) (a)-secondary xylem, (b)-hardwood

Tardigrade Admin · Accepted Answer

In older trees, the greater part of secondary xylem is dark brown due to deposition of tannins, resins, oil, guns, aromatic substances and essential oil in the central layers of the stem. These substances make it hard durable and resistant to the attacks of microorganisms and insects. This region is called heartwood.