Anatomy of Flowering PlantsHard
Question
As the secondary growth takes place (proceeds) in a tree, thickness of
Options
A.heaetwood increases
B.sapwood increases
C.both increase
D.both remain the same
Solution
As a result of coatinous secondary growth in sebsequent year, the older of secondary xylem becomes non-functional. Due to this activities of vessels become blocked by bladder- like ingrowths, which are called tyloses. Due to this the non-function xylem form hard and blackish in colour called duramen or heart wood. Now the function of secondary xylem is continous by younger rings called sapwood or alburnum with this passage of time and addition of new outer rings of secondary xylem more rings of sap-wood changes into heart wood. This is why the heart wood increases in diameter year after year but the sup wood remains almost in the same thickness.
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