Monostele

Again, in ectophloic medullated monosteles the presence of an internal endodermis between xylem and central parenchyma is rare ; on the other hand when an amphiphloic condition obtains, an endodermis often cuts off the internal phloem from the central parenchyma.

This is most readily done by reference to the sporeling: for there the axis is found to be traversed by a coherent monostele: and it is to the disintegration of this, together with the formation of commissural connections, that the complex structure of the adult is due.

This condition be conceived to be derived by repeated division of the monostele.

'Monosteles' comprising a ring of alternating xylem and phloem elements surrounding parenchymatous pith; 'monosteles' occurring in most genera...