Question
Biology Question on Anatomy of Flowering Plants
If the ? mode of differentiation of xylem is centrifugal, then it is
A
exarch
B
endarch
C
mesarch
D
centrarch.
Answer
endarch
Explanation
Solution
Primary xylem consists of protoxylem (first-formed xylem) and metaxylem (lateformed xylem). On the basis of order of differentiation of xylem element and position of proto and metaxylem, three different types of conditions are observed endarch, exarch and mesarch. In endarch condition, the differentiation of initial xylem begins near centre of stele and proceeds towards the periphery. Hence the protoxylern occurs towards the centre of the axis and metaxylem, towards the periphery of the axis. Such type of xylem is called endarch or centrifugal. This condition is seen in angiospermic stem.