morphology stem and bark
Ø Stem – stem is a organ which function both
as supportive and as conductive organs. as supportive organ ,it’s supports and
elevates the leaves and as conductive organ stem conducts water ,mineral and
sugar in vascular tissue between leaves , roots .
or
stem is the main axis of the plant
that consist of nodes and internodes.
Ø Shoot –shoot is the above ground part
of plant ,that consist of leaves ,buds, flowering stem ,flowering bud and the
main stem.
Ø Leaf primordium – Formation of immature leaves.
Ø Node – Point of attachment of leaf to
stem.
Ø Internode- A slender part between two nodes or
joints.
Ø Axil – The angle between the upper side of
the stem & a leaf ,branch or leaf petiole.
v Underground stem
Ø Notstocks –some perennial & biennial plants
growing under harsh conditions of cold or drought have underground stem.
Ø Bulbs –Shoot consist of a small amount of
vertical stem tissue & a massive quantity of thick fleshy storage leaves. Example-
Garlic,onion.
Ø Bulbils –it is small bulb like structure that
are formed within arial shoots or inflorescence of plant.
Ø Corm – a rounded underground stem storage
organ present in plants such as crocuses, gladioli & cyclamens consisting
of a swollen base covered by small scale leaves .
Ø Cormel- A small propogative corm growing at
the side of mature corm.
Ø Coudex- the thickened usally underground
base of the stem of many perennial herbaceous plants , from which new leaves
& flowering stem arise . Example- palm plant.
Ø Rhizome- It is found under the soil and grow
horizantlly with short internodes with some scale leaves. Example-
ginger,turmeric etc.
Ø Tuber- it is thick underground storage
stem, which bears outer buds, its have
lack of protective scale leaves. Example- Potato ; in some plants the tuber are
formed arial parts of plant. Example- dioscorea
Ø Stolen or runner – it is a stem with long internode
that runs just bellow the surface of the ground forming a new plantlet . when
come into the contact of soil . Example- strawberry.
v Arial stem
Ø Cladode – a flattened photosynthetic branch or
portion of stem that functions as or resembles as leaf .Eg –cactus.
Ø Succulent stem – this type stem contains high
percentage of water. It have high percentage of parenchyma tissue that may
store. High quantities of water , and the stored water use in drought periods. Example-
aloevera.
Ø Caudiciform stem- it is a fat, swellen perennial
storage stem which appears at or ground level. It is a non photosynthetic
shoots. Example- Elephant Foot,ming aralia.
Ø Pachycaul- “Pachy is a greek word means Large,
and caul are derived from latin word cauli means Trunk”,it is large woody trunk
like stem which swellen basally. The swellen region function in storage of
water . Example- bottle tree.
v Protective stem
Ø Thorn- A stiff, sharp-pointed woody
projection on the stem or other part of plant, that are modification of
auxillary shoot system . Example-karonda.
Ø Spines- it is sharp-pointed projection on
stem. It is modification of leaf or other part of leaves, auxillary buds. Example-
pineapple, agave.
Ø Pricle- a short pointed outgrowth on the
bark or epidermis of a plant, it’s looks like a thorn. Example-Rose, ber.
Ø Areole- it is modified, reduced,
non-elongating shoot, apical meristem bearing leaf spines. It’s mainly found in
cactus.
v Reproductive stem
Ø Scape- a scape is a long internode(non-woody leafless
segment between two leaf bearing region)that forms from the basal part or the whole of the
penducle,it is destined to bear one or more fowers or fruits. Example- onion,
garlic.
Ø Culm- Culm word are derived from latin
word “culmus” means “stalk”. It is a arial stem of grass of sedge. It is
originally refers to the stem of any plant. Example-bamboo tree,sugarcane.
Ø Tiller- a tiller is a stem produced by grass
plant, and refers to all shoots that grow after the initial parent shoot grows
from a seed, tiller are segmented, each segment processing it’s own two part
leaf. They are involved in vegetative propagation and also production of seed .
Example- Kentucky bluegrass.
v Other type stem
Ø Burl or lignotuber- lignotuber is swellen woody stem, at
slightly bellow ground level & just above the root system. It is a
protective & regenerative stem which emerges from following fire hazards. Example-
jarran, snappygum.
Ø Pseudobulb- pseudobulb is a storage organ found
in many epiphytic & terrestrial sympodial orchids . it may be egg shaped,
spherical or flat. Pseudobulbs store water and nutrients during dormat season. Example-
dendrobiaum catteya etc.
Ø Spur/dwarf- it is a modified shoot with every
shoot internodes- over which flower or leaves are borne. Example- Apple.
Ø Tendril- it is long slender coiling branch
which adapted for climbing . it is found on weak stemmed vine & functions
as support organ . Example-melon, cucumber etc.
v Stem habbit
Ø Caulescent – a plant with an above ground stem. Example-
pineapple,lettuce,carrot etc.
Ø Acaulescent – a plant that lacks of an above
ground stem, other than the infloroscence axis, acaulescent plant is biennial
herbs. Example- garlic ,onion ,chives.
Ø Arborescent – plant with tree like appearance and
size. Example-microcycas calocoma, macrozamia moorei etc.
Ø Frutescent- plant having habbit of a shurbs with
numerous, woody ,arial trunk.
Ø Suffrutescent- plant having the habbit basally
woody,apically herbaceous and perennial in nature. Example- butterfly bush.
Ø Clambering or scadent- stem sprawling a cross objects
without specialized climbing structure.
Ø Climbing- stem growing upwards by means of
tendrils, petioles or adventitious roots . Example-
cucumber,grapevine,moneyplant etc.
Ø Prostrate – stem trailing or laying flat ,but
rooting not occurs at nodes. It’s also called
Ø Repent- stem reaping or laying flat, but
rooting occurs at nodes. Example- burmuda grass.
Ø Decumbent- laying basally flat on ground, but
apically growing upwards. Example- basella, portulaca etc.
v Branching pattern
Ø Indeterminate branching- this type shoot have ability for
unlimited growth. It’s apical meristem is continues active & resultant
growth is inderterminate. Example- apple , white birch etc.
Ø Determinate- this type shoot have not potential
for unlimited growth. it’s apical meristem is terminate in flower
,inflorescence or thorn,tendril etc. Example- potato,cucumber etc.
Ø Hepaxanthic- a determinate shoot that completely
terminate into flower or inflorescence. Hepaxanthic plants bears flowers only
once in their life cycle. Example- banana bamboo etc.
Ø Pleonanthic- an indeterminate shoot that bears
lateral flowers but continues vegetative growth occurs in terminal shoot. It’s
type branching pattern mainly sean in palmae or arecaceae family plant .
Ø Monopodial- when stem axis is derived from
growth of single meristem, is called monopodial
Or
When the terminal bud
continues grow as a central plant grow from a single point . Example- fagus.
Ø Sympodial- if a stem axis are derived from
multiple apical meristem.
Ø Dichtomous- it is a rare type of branching in
which a single meristem divides equally into branches. Example-mango,congress
grass.
Ø Trunk- undivided stem of a palnt is termed
as stem.
Ø Twing- recent growth of branches of trees
or shurbs as termed as twings.
Ø Buds- immature shoot system that develops
from meristem regions.
·
mined type bud-
which develop both vegetative & floral growth .
·
collateral buds- usally one bud are forms per node, but in some plant more than one
auxillary bud oriented sideways . they are known as collateral buds.
·
Superposed buds- if 2 or more auxillary buds oriented vertically they are known as
superposed buds.
·
Pseudoterminal buds – some times the apical
meristem of a shoot aborts. Then auxillary bud near shoot apex may continue extension growth & assumes the
function of a terminal bud known as pseudoterminal bud.
Ø Bud scale-it is the outer most leaves of the
bud, which act as a protective bracts. It is also known as scale leaves.
Ø Bark-it is the outer most layer of the
stem,which is composed of the tissue outside the vascular cambium of plant . it
is also known as periderm.
v Type of bark
·
Exfoliating leaves- it is a bark that cracks or splits into large sheets. Example-
terminalia arjuna, lipistic.
·
Fissured –
this type of bark are splits or cracked into vertical or horizontal grooves.
·
Plated- bark
which splits or crack with flat plated between the fissures. Example-
persimmon.
·
Shreddy – the
bark which are coarsely fibrous. Example- yellow birch.
·
Smooth- a non
fibrous bark without fissures, firbres, plates or exfoliating sheets . it’s
bark are smooth and free from any cracks .
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- Fundamentals of horticulture
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