Organization of Vascular tissue Flashcards
What is the vascular bundle?
The area where there is a collection of xylem and phloem which is at the interior of the cortex.
How are the vascular bundles arranged in dicots and basal angiosperms? Pizza
The triangular bundles are arranged in one ring around the pith with Phloem on the outside and xylem on the inside.
How are the vascular bundles arranged in monocots?
Vascular bundles are distributed as a complex network throughout the inner part of the stem.
Between the bundles are parenchyma
How are all vascular bundles collateral?
Contains both phloem and xylem strands running parallel to each other.
What is the primary Xylem?
The xylem of the vascular bundle
There is also xylem fibers (mechanical sclerenchyma) and xylem parenchyma
What is the primary phloem?
The phloem in the vascular bundle
There is also phloem fibers, phloem sclerids
How do stems grow?
By creating new cells at their shoot tips the apical meristem which keep their ability to divide.
When daughter cells that start expanding and growing they push the apical meristem upwards
What are Subapical meristems
The region just below the apical meristem which has cells that are also dividing and growing, producing cells for the region below.
What is something that happens in Subapical meristems that don’t happen in apical meristems?
Cells differentiate and stop dividing
What are Protoxylem?
These are cells that differentiate from the subapical meristem these are the first xylem.
Why are the secondary walls of protoxylem limited?
Protoxylem need to remain flexible while cells around them elongate which means that their secondary cells wall needs to be flexible and not ridge.
What secondary walls are the protoxylem limited to?
Helical or annular
What are metaxylem?
These are xylem whose cell walls remained flexible due to their need to stay in this state because of of the elongating cells around them. This allows them to grow very large as they are not restricted by the secondary wall.
Once the cells around them stop elongating depositing a stronger cell wall is no problem.
Protophloem
The first phloem to develop before the plant organ has completed its growth. Found on the exterior of the vascular bundle.
Has smaller narrower elements than metaphloem
Gets crushed in secondary growth
What is Metaphloem
This is the later formed phloem that develops after the plant organ has finished growing and these are closes to the metaxylem.
Last longer may get crushed in secondary growth
