The Development of the Vascular System
PROTOSTELE
AMPHICRIBAL
DISSECTED
SIPHONOSTELE
ECTOPHLOIC
AMPHIPHLOIC
DICTYOSTELE
AMPHICRIBAL
AMPHIVASAL
EUSTELE
Here we see the development of vascular
systems, in which the LEAF dominates the vascular system.
Vascular bundles are arranged
in a RING. May be COLLATERAL,
or BICOLLATERAL.
Stele
Cortex
ATACTOSTELE
Stem contains a ring of
vascular bundles, and then a
spiral towards the centre.
This represents the highest
level of development of the
vascular system in the
stem. Stippling and hashes
left out for clarity.
KEY:
XYLEM
PHLOEM
STEMS and ROOTS
Structurally, the same cells are found, but arranged
differently. In addition, little if any need for structural support
in roots. Both contain cortex in young organs, but not all
roots contain a stele.
The stem: Clearly defined
CORTEX and STELE
The Root: CORTEX, but
STELE replaced by parenchymatous
central region -- more “stele-like in
MONOCOTYLEDONS than in
DICOTYLEDONS