Botany Class 2

sieve cells

sieve cells

long, slender connecting cells in phloem sieve tube elements are cells in angiosperms, sieve cell in gymnosperm assoicated with specialized parenchyma cells called albuminous cells usually not derived from the same cell by mitosis, but perform similar role as companion cell

sieve tube elements

found in phloem aligned end to end into sieve tubes associated with specialized parenchyma cells (nucleated companion cells) derived from the same cell by mitosis and have numerous plasmodesmatal connections both function together in phloem transport

sieve tube elements and companion cells

P-proteins staunch wounds continuous wall called a sieve plate

Medullary rays

"pith rays" composed primarily of parenchyma and transport for nutrients for occlusion of xylem vessels for deposition of terpenes in formation of heartwood

Vascular bundle:Eudicot

In secondary growth, the vascular cambium forms between the primary xylem and primary phloem and produces new xylem to the inside and new phloem to the outide

Protoxylem

the part of the primary xylem that differentiates early, while adjacent cells are still elongating

Phloem

Living vascular tissue that carries sugar and organic substances throughout a plant produced in primary and secondary growth

Protophloem

The part of the primary phloem that differentiates early, while adjacent cells are still elongating during primary growth often stretched and destroyed as part of expansion and elongation analogous to protoxylem

Protophloem vs. protoxylem

both elongate, dead at maturity, heavily lignified, provide support but also conduct water and mineral nutrients inside the stem

companion cells

the active cells found next to sieve tube elements that supply the phloem vessels with all of their metabolic needs

where is protoxylem

Pectin

a soluble gelatinous polysaccharide that is present in ripe fruits and is extracted for use as a setting agent in jams and jellies

primary wall

alive during maturity

secondary wall

if lignified, dead a maturity if not lignified, marenchyma, alive at maturity

Xylem froms and function

tracheary elements, tracheids, and vessel elements- conduct/transport water and minerals fibers- support and sometimes storage parenchyma- storage

vessel elements

A short, wide, water conducting cell found in the xylem of most angiosperms and a few nonflowering vascular plants. Dead at maturity, vessel elements are aligned end to form micropipes called vessels.

Phloem form and function

sieve elements- long distance transport of food Sieve and albuminous cells, sieve-tibe elements- materials and signaling molecules Scelerenchyma, fibers, sclereids- support, sometimes storage parenchyma-storage

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