SHOOT APEX Flashcards
points at which leaves are attached
nodes
stem segments between nodes
internodes
has the potential to form a lateral shoot
axillary bud
located near the shoot tip and causes elongation of a young shoot
apical bud
helps maintain dormancy in most non-apical bud
apical dominance
structure that permit the passage of gas inward and outward
lenticels
characteristic scar on stem axis made by leaf abscission
leaf scar
small modified leaves for protection from desiccation
bud scales
immature leaf on the shoot
leaf primordium
the portion of the internodes above the node. made up of actively dividing cells responsible for the elongation of the monocot stem
intercalary meristem
outer group consisting of one or more peripheral cell layer, these cells divide anticlinally
tunica
lies below the tunica and initially has a single layer of cells
corpus
dome-shaped mass of dividing cells at the shoot tip
shoot apical meristem
models of tissue organization in the shoot apex
apical cell theory
histogen theory
tunica-corpus
pteridophytes - base is directed towards the surface of the apex
gymnosperm - surface meristem
apical cell theory
each develop from independent group of initials
meristems are destined from the beginning to produce certain tissues
histogen theory
outermost
dermatogen
central
plerome
between dermatogen and plerome
periblem
no constant relationship can be traced between the particular initials of the promeristem and the inner tissues of the shoot
tunica-corpus theory
outermost layer
surrounds inner cell mass
anticlinal division
tunica
inner cell mass
divides in all directions
enlarges in volume
corpus
corpus = portions of tunica
central zone
below central zone, becomes the pith
rib zone/pith rib meristem
encircles the other zones, eumeristem
peripheral zone/peripheral meristem
initiated by periclinal divisions at the side of the apical meristem
origin of leaves
