Xylem - III

Heartwood

Sapwood

Cambium

Phloem

Periderm

Prominent heartwood

Patterns in wood components

Gymnosperm type

• Ground tissue only tracheids – no vessel elements

• Most gymnosperms

• Vessel-less dicots - Amborella, Drimys, etc

Fagus sylvatica type

• Ground tissue consists of tracheids but vessel elements are present

• Tracheid-vessel element pitting

• Paratracheal parenchyma scanty – in isolated strands

• Vessel system of one ring does not contact the next ring

Daphne mezereum type

• Similar to Fagus sylvatica type except ground tissue has regions of tracheids and regions of fiber tracheids

• Vessel elements only located among tracheids

Alnus glutinosa type

• Ground tissue is fiber tracheids

• Tracheids restricted to latewood as bridges to next annual ring

Saurauia bracteosa/Juglans regia type

• Ground tissue tracheids

• Vessel elements surrounded by a sheath of axial parenchyma

• Little contact between vessel elements and tracheids

Rhamnus cathartica type

• Ground tissue has regions of libriform fibers and regions of tracheids

• Vessel elements occur among the tracheids and have pit contact

• Little paratracheal parenchyma

• Tracheids and vessel elements of one ring in contact with those in adjacent rings

Quercus robur type

• Ground tissue has regions of libriform fibers and regions of tracheids

• Vessel elements are isolated from the tracheids by complete sheaths of paratracheal parenchyma

• Tracheids and vessels elements in one ring in contact with those in adjacent rings

Aesculus hippocastanum type

• Ground tissue libriform fibers

• Vessel elements mixed among fibers

• Scanty paratracheal parenchyma

Acer pseudoplatanus type

• Ground tissue dead libriform fibers

• Vessels surrounded by complete sheaths of living fibers

Bombax type• Ground tissue parenchyma

Collection of violins made by Antonio Stradivari at the Metropolitan Museum of art in New York City.

Stringed instruments made in Italy in the 16th and 17th century by Stradivari, Guiseppi Guarneri, Andrea Amati, Carlo Landolfi, etc are considered the finest instruments in existence.

Scientists in various fields have often wondered what makes these instruments so great.

Modern viola made from spruce, poplar, and maple as a copy of a 1756 Landolfi viola

Growth rings can tell the age of the tree

Growth rings are not uniform and reflect the environmental conditions during the year of formation

Crossdating

Crossdating

Actual cores used for crossdating