primary and secondary growth Flashcards
(15 cards)
what is primary growth?
-only in non woody/non woody parts of plants
-roots are covered by root cap protecting the apical meristems as the root pushes out
what are the 3 overlapping areas of primary growth?
cell division: new root cells are produced
elongation: root cells elongate
differentiation: cells become specialized in structure/function
describe primary growth in shoots
dome shaped mass of dividing cells allow the stem to grow
what are mesophylls and guard cells?
-leaf ground tissue, photosynthesis
-regulate open/closing of stomata
what species undergo secondary growth?
-all gymnosperms
-many eudicots, rare in monocots
-occurs in stems and woody plants, rarely in leaves
where does secondary growth occur and what does it do?
-occurs in vascular and cork cambiums
-increases diameter
where are the secondary phloems and xylems?
xylem and phloem surround vascular cambium
what is the importance of secondary phloems and xylems?
phloem: transports sugar, storage, growth and maintenance
xylem: water/nutrient transport, structural support, storage, tree rings
how does the vascular cambium produce phloem and xylem?
phloem: outward production
xylem: inward production
what does the cork cambium do?
known as periderm, produces cork cells that form outer protective layer
what does bark consist of?
secondary phloem, cork cambium, and cork
what happens to the secondary xylem as the tree/woody plant ages?
older layers of secondary xylem no longer transport (sapwood still transports)
what happens to the secondary phloem as the tree/woody plant ages?
they sloth off and do not accumulate
what is a unique characteristic about the periderm?
it is impermeable to water and gases
what do lenticels do?
allow for gas exchange b/w living cells in stem or root
