Wood Lab Flashcards
what is responsible for secondary growth in plants?
2 secondary meristems
which 2 secondary meristems control secondary growth?
- vascular cambium
2. cork cambium
what is another name for the cork cambium?
phellogen
what is produced by the vascular cambium?
secondary xylem to the inside, secondary phloem to the outside
as a tree ages, what happens to the primary xylem and phloem?
xylem ceases to function and phloem is stretched and destroyed
the bulk of a tree is composed of what?
non-functional xylem
what replaces the epidermis in woody plants?
periderm
what is the function of the periderm?
outer protective layer
from whence is the periderm derived?
cork cambium
what does the periderm consist of?
phelloderm cork cambium cork (phellem)
what does bark consist of?
periderm and secondary phloem
what plant groups can have secondary growth?
gymnosperms and woody dicot angiosperms
what plant groups are hardwoods?
angiosperms
what plant groups are softwoods?
gymnosperms
at a cellular level, what is contained in hardwoods?
- parenchyma
- sclerenchyma
- tracheids
- vessels
at a cellular level, what is contained in softwoods?
- parenchyma
- sclerenchyma
- tracheids
what are the three cuts of wood?
transverse (c.s.), radial, tangental (both longitudinal)
what does a transverse section of wood look like?
looking at top of straws
what does a radial section of wood look like?
woven fabric
what does a tangental section of wood look like?
wavy with clusters of resin ducts
what are lenticels? Their function?
parts of periderm containing numerous intercellular air spaces. Function: gas exchage
why cant monocots produce secondary growth?
their vascular systems are closed
what can cause “woodiness” in monocots?
sclerids
trees with distinct annual rings are
ring porous
trees without distinct annual rings are
diffuse porous
how can a gymnosperm be identified from an agiopserm on a slide?
- absence of vessels
2. presence of resin canals
what are wood macerations/
woods ground up and/or digested to separate cell types
what are the 5 types of pattern variations in tracheids?
- annular
- spiral
- reticulate
- scalariform
- pitted
in roots, where are the vascular cambium and cork cambium derived from?
pericycle
what are young branches called?
twigs
what are the three regions of a twig?
- apex/terminus
- nodes
- internodes
what is the apex of a twig?
the growing tip
what are the two types of buds possible in twigs, and where is each located?
- lateral (axillary)
2. terminal (apex)
size and shape of leaf scar depends on
size and shape of petiole
what protects leaves in the winter?
scales
if a bud has no scales, it is said to be
naked
