Outgrowths fromadjacent parenchymainto a vessel, partially orcompletely blocking thevessel lumen.

Tyloses growth in bay laurel “cousin”,tangential section, outgrowths from rayparenchyma

TYLOSESTYLOSESFORMATIONFORMATION

Occurs when

•Air enters vessels

•Vessel-rayparenchyma pits large

•Parenchyma cells notdormant

White Oak. SEM view of cross section. Photo.SUNY

Normal part of heartwood formation &

Response to injury

Wilt diseases often related to losing waterconduction ability because fungi tap intovessel, and tyloses are formed stoppingwater conduction.

Earlywood vessels filled with tyloses.SEM View. Photo courtesy of SUNY.

Earlywood vessels filled withtyloses. Handlens view 3earlywood zones shown.

Earlywood Vessels Filled With TylosesBlack Locust (Robinia pseudoacacia

RED OAK VS WHITE OAK

Red Oak. Only a few of theearlywood vessels have tyloses.Latewood vessels rounded in outline,visible with handlens

White Oak. Most earlywoodvessels have tyloses. Latewoodvessels angular in outline, usuallybarely visible with handlens.

If tyloses are abundant, wood is

* difficult to dry,

* difficult to impregnate with decay-preventive or stabilizing chemicals,

* difficult to infiltrate with pulping liquors.

Tyloses block vessels and lower woodpermeability.

Earlywood vessel element filled withtyloses. SEM View.

Earlywood vessel element filledwith tyloses. Maceration. LightMicroscope. 10x

Vessel Elements Filled With TylosesWhite Oak