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Vessel member & tracheids |
Vascular plants have
two kinds of
Tracheary Elements:
Tracheids & Vessel
Members.
Conifers
have only tracheids.
Angiosperms have also
vessels.
Vessels are made from a xylem
cell type called a xylem vessel member. Vessel members are a
specific long and narrow (but generally shorter than tracheids)
cell type with primary and secondary cell walls found in the
xylem. Vessels are vertically aligned tubes or "pipes" made up
of many dead cells that transport liquids in xylem. Vessels are
found in Angiosperms . Vessels begin as single living cells that
join at their top and bottom to form a short conduit. Other
vessel conduits connect from the sides to form a transport
pathway from root tips to leaf tips. Vessels curve and join with
other vessels.
The newly formed vessels do not become functional until the end
walls or septa between the vessel cells rupture. These openings
in their end walls are the "Perforation Plates".
Perforation plates
facilitate water movement in the Xylem
Principal characteristic of vessel elements:
-
Dead at functional
maturity
- Shape: Vessels are composed
of elongated vessel
members in series connected by
Perforation plates.
- Cell wall: primary and
secondary, lignified.
- Function: Xylem Chief
water-conducting element in Angiosperm xylem.
Compare whit:
Tracheids |
