Secondary Growth

How does second growth initiate in stems

In eustele structures, the vascular cambium that is responsible for producing wood and secondary phloem.

Secondary growth in pines

axial regions full of tracheids w- bordered pits, rays are comprised of parenchyma.

Secondary growth in flowering plants

Flowering plants have vessels in secondary growth, but gymnosperms usually have tracheids instead. They also have fibers, which conifers and other softwoods lack. 

What does bifacial vascular tissue refer to

Cells are created on both sides of the layer, like cork cambium

Purpose of bordered pits in pines, do flowering plants have them

In pines, tracheids have bordered pits, which limit embolisms that can stop water flow. Flowering plants have sieve tube cells along with companion cells, which achieve this function . 

Ring porous wood

only occurs in plants with vessels, such as flowering plants. The vessels vary in size, with larger ones associated with early wood-periods of heavy rainfall

Diffuse porous wood

the vessels are similar in diameter.Can live in very wet environments, but fiber cell walls change in thickness depending on the season 

How do axial regions differ from rays

Axial regions are xylem and phloem that run vertical, rays are made up of parenchyma cells, moving food between secondary xylem and secondary phloem

How do cells in conifer phloem differ from angiosperms

Only has sieve cells in axial regions and work with albuminous cells. In flowering plants, its sieve tube elements that work with companion cells.

What happens to old phloem

It gets crushed and pushed outward with bands of periderm, forming the rhytidome

Where does cork cambium originate from and how does it form

Cork cambium originates just under epidermis, sandwiched between cork cells above and cork parenchyma below. They produce the periderm, responsible for widening trunks-stems in woody plants and replacing outer epidermis

Location and function of cork cells

Cork cells are dead and filled with suberin, a fatty acid. Provide structure and form outermost layer of bark. Dead at maturity

Location and function of cork parenchyma

These are alive and can photosynthesize, they usually develop from and underneath the cork cambium layer closer to the phloem

How does the periderm form

It forms when cork cambium divides inside the epidermis, within the cortex. Above this layer are the cork cells, which are dead and contain suberin. Below this layer is your  phelloderm, or cork parenchyma, which can still photosynthesize