Morphology

Of Angiosperms
 Morphology
• Morphology: The study of form, structure and development of plant
and their parts.
• The study of Flowering plant is called Anthology.
• First Flowering plant appeared in Jurassic Period.
• Angiosperms are flowering, phanerogamic, spermatophytic,
sporophytic plants.
Plant

Root System Shoot System

.
 Root
• Underground, non-green and descending part of plants.
• During seed germination, first structure to arise is root.
• The root is the descending organ of plants and are +vely geotrophic.
Exception:-
i) Corolloid roots of Cycas: Apogeotropic
ii) Pneumatophores of mangroove plants: -vely geotrophic
• The main root (primary root or tap root) is formed from the radicle.
Note: RadicaL = Leaf insertion.
• The lateral branches of main root are called secondary roots which are further
branched to form tertiary roots.
• The lateral roots arise from pericycle (in between two protoxylem points) i.e.
endogenous.
• Root is positively geotrophic and negatively phototropic
• Maximum edible food-obtained from roots.
• Root possess root cap (at tip) and root hairs.
 Root
• Root hair -> unicellular.
• Root hair are exogenous i.e. arise from epiblema of mpiliferous layer.
• Root helps in fixation, absorption and conduction.
Note: In a hydrophyte Podostemon, root performs the function of
assimilation and reproduction. It is a plant that is all root ie. plantless root.
Other examples of plane roots are: Arceuthobium, Rafflesia, Sapria,
Monotrapa. [@PA Ra S Mani]
• Roots are absent in some angiosperms i.e. rootless plant.
 Zones or Parts of Roots
• Root cap (calyptra).
• Cap like covering present at the apex of root.
• Root tip is sub terminal in position because of root cap over it.
• It is made up of thin-walled cells and is regenerable.
• • The main function of root cap is to protect the young growing cells of
apical region / protection of root meristem.
• Sensor cells = Statolith and Amyloplast rich cells = Denser cells in root cap
is vital for gestrupism, perception and sensing the direction of gravity.
• *Cells of root cap are rich in golgi bodies and mucilage.
• • The function of mucilage is to lubricate the soil particles.
• Root cap also known as calyptra • Roots without rootcap: Coralloid
develops from calyptrogen in root, hydrophytes,
monocots pneumatophores, mycorrhizal
dermatogen/protoderm roots, epiphytes,
(epiblema) in dicots.[@d for d] haustorial/sucking roots
(parasites).

• Generally, a simple root cap is

present besides some exceptions
Eg. in Pandanus (screw pine)
multiple root cap is present and
also has largest root cap while in
aquatic plants i.e. hydrophytes,
the apical portion is protected by
root pocket (not regenerable) in
place of root cap. Eg.
Eichhornia(water hyacinth), Pistia
(water lettuce), Lemna.

• Root pocket acts as balancers.

ii. Region of cell division or meristematic region or growing region:
• Root meristem is sub-terminal/sub- aptical in position.
• This region is present just above the root cap.
• In this region cells divide actively hence it is the main growing region of
the root.
• It is also called zone of cell formation.
iii. Region of cell elongation:
• Maximum mineral absorption occurs from here.
• Upper to meristematic region, elongated cells are found which is
responsible to incre the length of root.
• Actual increase in root length occurs in this region.
iv. Region of cell maturation (cell differentiation region):
• This region is characterized by the presence of unicellular root hairs formed
by epidermal cells.
• The function of root hair is the absorption of water and minerals.
• Matured cells are found in this region.
• Lateral roots arise from this maturation region of pericycle (endogenous)
• Xylem and phloem differentiate here.
• Food is stored in roots in this region.
Root system

Tap Root system Advantatious Root system

Origin of root from radicle of Origin from any part other than
embryo radicle.
It persists through out the life of May be aerial or underground.
plant eg. If develop from stem cauline
Develop secondary root, tertiary root; if from leaf = foliar
root and rootlet. root/epiphyllous roots.
Growth towards gravity
Special Points:
• In dicots, radicle elongates, tapers, swells, becomes prominent as primary
root.
• In monocot, radicle dies immediately after germination of seeds, later
adventitious roots arise from any portion other than radicle. Eg. from stem
in maize and leaf in Bryophyllum, Bignonia. Such matured plants possess
adventitious root only.
• Roots arising from callus in tissue culture are adventitious.
 Modification of Root
• Modification of tap root:
• 1. Fleshy/storage tap root:
• Some of the tap roots become fleshy due to storage of food
material.
• a. Conical: Cone like with broad base and tapering towards apex eg.
Carrot (Daucus carota) [Family Umbeliferae]
• b. Fusiform: Spindle like tapering at both ends with middle portion
thicker eg. Radish (Raphanus sativus).
• c. Napiform: It is 'top' like. Swollen base with abruptly tapering
towards the apex Turnip (Brassica rapa)
• d. Tuberous: Swelling is irregular. Eg. Mirabilis jalapa (4 O'clock
plant)
• Nodulated (Tuberculated) tap root (Root nodules):
• • Primary and secondary roots of some dicot have root nodules.
• Nodulated roots make the plant rich in proteins.
• Eg. Legume (papilionaceae)
• Rhizobium forms nodules in roots.
• Nodules are found on primary to secondary roots only.
• Rhizobium fixes nitrogen.
• Nace Host provide nutrient to Rhizobium and symbiont provides nitrogen to
host.
• Inside nodules pigment called leghaemoglobin is present.
• Function of leghaemoglobin is to protect the enzyme nitrogenase, supply Or
to vigorously respiring bacteria.
• Relation between bacteria and legume having nodulated roots is that of
Symbiosis. [LE]
• iii. Pneumatophores / Respiratory roots / Breathing roots:
• In mangrove plants ie. plants growing in saline marshes, the branches of tap
rout grow vertically upwards showing negative geotropism or apogeotropism.
• • These roots are called pneumatophores, which have minute pores on their
exposed portion called pneumathodes to take 02.
• Note: Pneumathodes are anatomically and morphologically similar to
lenticels. Eg Rhizophora, Avicenia, Sonneratia, etc.
• ReplyForward
• Add reaction
• Iv. Buttress root
• At the base of main stem thick woody types of laterally compressed
horizontal root which gives additional support to the plant.
• Eg Ficus religiosa (peepal), Bombax ceiba (simal), Ficus elastica (rubber
plant)
• These roots are formed jointly by base of trunk and tap root.
• v. Mycorrhizal root:
• Root hair and root cap absent
• Fungal hyphae provides phosphorus nutrient to host when necessary,
eg. Pinus, Betula (as ectomycorrhiza).
• Fungal hyphae covers the entire root
• Note: Mycorrhiza is also associated in roots of orchids as
endomycorrhiza
• vi. Reproductive root:
• These tap root develop adventitious buds and helps in vegetative
propagation eg:
• Dalbergia.
Modification of Advantatious
Root
• 8. Modification of adventitious root:
• L Fleshy: Some adventitious roots become fleshy due to storage of
food material.
• a. Tuberous or single root tuber: Swelling is single, have no definite
shape. Eg: Sweet potato (Ipomoea batatus)
• b. Fasciculated roots: Have definite shape, swelling is in cluster (ie.
in groups) at base of stem. Eg. Asparagus, Dahlia
• Note Inulin (also called Dahha starch) is obtained from Dahlia
plant. Inulin is the polymer of fructose.
• c. Palmate root: Swelling is in branched roots giving an appearance
like a palm. Eg. Orchis
• d. Moniliform or beaded root: Swelling is in interval. Eg.
Momordica charantia (bitter gourd)
• e. Nodulose: Swelling is in tip. Eg. Curcuma domestica (turmeric),
mango ginger (Curcuma amanda)
• L Annulated root: Swelling is ring like. Eg. Cephaelis, Psychortia
(Ipecac) etc.
• ii. Pillar or prop root:
• Arises from large branches of some trees, which
possesses thick, woody types of root.
It gives support to the plant and it is also
hygroscopic (help in absorbing water).
It has lenticels for aeration.
Eg. Ficus benghalensis (Banyan tree), Rhizophora.
• iii. Stilt root:
tres obliquely from lower nodes of the plant and
gives additional support to pla by fixing in soil.
Eg Sugarcane (Saccharum officinarum), Maize (Zea
mays), Screw pine (Pandun tinctorius). (@SMS]
• iv. Climbing root/Clinging root:
Some climbers possess adventitious roots in its
node or internode, help in fixation.
Eg. Pothos (money plant), paan (Piper betle), Ivy
(Hedranepalensis), vanilla, orchi @VIP
internode produces adventitious root.
• v. Haptera:
In aquatic plant Podostemon, leaf margin
produces root (thallus like root).
Helps plant to attach on the substratum.
Extensive root produced from leaf margin
rendering plant aphyllous (leafless)
• vii.Photosynthetic / Assimilatory root:
Some aquatic plants have green root, which helps in
photosynthesis.
Eg. Trapa (water chestnut). Tinospora, Taeniophyllum.
[@3T]
. :viii. Floating root:
Some aquatic plants have leafyfloating roots.
Helps in balancing
Eg. Pistia, Eichhornia, Jussiaea
• ix. Root thorns: Roots of some plants arise from the stem
and change into thorns performing the protective
function.
Eg. Pothos (money plant), Acanthorhiza.
• x. Contractile root: arises from underground stem. Eg.
Crocus, Allium cepa (onion), Fressia.
• xi. Reproductive root:
• Some adventitious roots have capacity to reproduce
(by producing adventitions buds). Eg. Dahlia, sweet
potato, Trichosanthes dioica (parwal)
• xii.Epiphytic roots: Epiphytes have
• a. Clinging root: for fixation Eg. orchids.
• b. Hygroscopic or epiphytic: Thick type of root which
absorbs moisture from the surroundings by the help of
spongy tissue called velamen tissue (dead).
• • Velamen absorbs moisture from atmosphere and
protects root. Velamen bearing roots is epiphytic
orchids.
• Note: Velamen in roots of terrestrial orchids - Sobralia,
Phajas In epiphytic roots, there is no root hair and root
cap.
• xiii. Leaf root:
• Leaf of some aquatic plant modified into root, which helps in
balancing. Eg. Salvinia (aquatic pteridophytes).

• SECIAL POINTS:
• Nest roots: Adventitious roots in pitcher of Dischidia.
• Note Dischidia and Nepenthes, both have pitchers but in
Dischidia there is devoid of lid in pitcher.
• Dischidia is non-insectivorous plant.
• Functions of Root
• Roots support the plant by keeping it fixed firmly in the soil.
• Roots absorb water and mineral.
• Stores food inside them.
• Roots hold the soil particles together.
READ AND D IG EST
• Red Root is beet root.
• Sugar is extracted from beet also.
• Adventitious roots are adventitious in their place of origin.
• Reproductive adventitious root occurs in D ahlia,sw eet potato (Ipomoea),etc.
• Reproductive tap roots occur in D albergia.
• Thick unbranched roots found in corms and rhizomes of some plants are
contractile.
• Sucking roots occur in Mistletoe.
• W hite spongy floating roots occur in Jussiaea.
• Edible part of sw eet potato is adventitions root tuber.
• Lateral roots arise from primordia developed by division of pericycle cells in
betw een tw o protoxylem points.
• Epiphytic roots are also called as hanging roots.
• Maximum mineral absorption takes place from zone of cell elongation.
• Roots are modified into thorny branches in Acanthorhiza.
• Root hairs are absent in aquatic plants,mycorrhizal roots,parasitic roots and
epiphytic roots
• The roots w hich arise from the leaf are called epiphyllous roots.
• Cuscuta possess haustoria or sucking roots.
• Maximum w ater absorption takes place from zone of cell maturation.
• G eotropic response is perceived by root tip.
• Adventitious roots are recognized by their origin.