BSc.- I Biotech - DAV College Jalandhar

Transcription

Department of Botany, DAV College, Jalandhar (PB.)
BOTANY
Lab Manual
BSc.- I Biotech
Semester I
266
PLANT SYSTEMATICS
Brassica campestris
Habit:
Annual or biennial herb of winter, cultivated as pot-herb too.
Root:
Branched tap root.
Stem:
Young plants have reduced stem but in older it is erect and branched, cylindrical,
herbaceous above ,woody below, hollow, green, glabrous, hairy.
Leaf:
Young plants have radical leaves but in older plants it is cauline and ramal. Leaves
simple, lyrate, exstipulate, sessile or subsessile lower leaves incised and lyrate, upper
leaves ovateor ovate lanceolate or auriculate, hairy, herbaceous, reticulate unicostate.
Inflorescence: Corymbose raceme.
Flower:
Ebracteate, Ebracteolate, pedicillate, complete, regular, actinomorphic, bisexual,
hypogynous, cyclic,yellow.
Calyx:
4, free, polysepalous, in two whorls, outer whorl antero-posterior, the two laterals
form inner whorl and are saccate with a pouch like structure at the base to store
nectar, green or yellowish green, lanceolate, margin of sepals entire, apex acute,
inferior.
Corolla: 4, free, polypetalous, cruciform, clawed, longer than sepals, spreading, valvate,
yellow with entire or slightly extrorse margin, inferior.
Androecium: 6, polyandrous, tetradynamous, 4 longer stamens form antero-posterior pairs and
are arranged in an inner whorl and two smaller lateral stamens form the outer whorl.
Anthers basifixed, bithecous, dehiscence longitudinal with longer extrose anthers and
shorter introse anthers; four distinct green dot like nectar glands are present at the
base of the outer and inner paired stamens, inferior.
Gynoecium: Bicarpellary, syncarpous, superior ovary, unilocular becomes bilocular by the
formation of false septum called replum, parietal placentation, many ovules, style
short, stigma bifid.
Fruit:
Siliqua
Seed:
Non-endospermic, many, small in size with folded cotyledons.
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Citrus aurantium (Orange)
Habit:
A small tree, cultivated in India for its edible fruits and medicinal properties.
Root:
Branched tap root.
Stem:
Aerial, erect, branched, solid, woody, green,glabrous.
Leaf:
Evergreen, cauline and ramal, alternate, exstipulate, petiolate, winged petiole,
compound unifoliate actually trifoliate but the two lateral leaflets fall off leaving a
scar, terminal leaflet unicostate reticulate, gland dotted, glaucous. A spine is present
in the axil of each leaf which is the modified first leaf of the supressed axillary shoot.
Inflorescence: Solitary, axillary or group of flowers in axillary position.
Flower:
Ebracteate, ebracteolate, pedicillate, complete, regular, actinomorphic, bisexual,
pentamerous, cyclic, hypogynous, white and scented.
Calyx:
5, gamosepalous, cup shaped, pentafid, green, gland dotted, inferior.
Corolla: 5, polypetalous, petals lanceolate, sweet scented, gland dotted, white, imbricate,
alternating with sepals, inferior.
Androecium: Many in one whorl, polyadelphous, filamemts united into groups at the base.
Bithecous, dorsifixed anthers introse longitudinal dehiscence, yellow anther lobes,
inferior.
Gynoecium: Polycarpellary syncarpous, superior, multilocular ovary with axile placentation,
style short, stigma capitate, a large honey secreting disc present below the ovary,
ovules many in each loculus.
Fruit:
Berry (Hesperidium)
Seed:
Many, non-endospermic, testa mucilaginous.
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Murraya exotica (Kaamini)
Habit:
Evergreen small cultivated ornamental tree.
Root:
Branched tap root.
Stem:
Erect, branched, woody, cylindrical, solid, glabrous.
Leaves:
Evergreen, ramal and cauline, exstipulate, petiolate, imparipinnate, 3-7 pinna.
Leaflets: Alternate, shortly stalked, ovate, obovate or rhomboidal, entire, acute apex dark
green, shining above, unicostate reticulate.
Inflorescence: Solitary axillary or solitary terminal.
Flower:
Ebracteate, ebracteolate, pedicillate, pentamerous, complete, regular, actinomorphic,
bisexual, hypogynous with a distinct nectar secreting disc below the ovary, cyclic,
highly fragrant, greenish white or white.
Calyx:
5, gamosepalous, pentapartite, green, small, inferior.
Corolla: 5, free, oblong-lanceol0ate, gland dotted, greenish white, fragrant, reflexed with
spreading above, imbricate, sweet smelling, entire, acute apex, alternisepalous,
inferior.
Androecium: 10, polyandrous, diplostemonous, the outer 5 alternating with the petals and inner
five opposite the petals, the filaments of outer stamens are longer than those of inner
stamens, anthers bithecous, basifixed, young anthers hairy, dehiscence longitudinal
introrse , inferior.
Gynoecium: Bicarpellary, syncarpous, ovary superior, bi-trilocular, two ovules per locule, axile
placentation, ovules anatropous, and ovary lies on large nectariferous disc, single long
green style, bifid sticky stigma.
Fruit:
Red and ovoid berry, gland dotted with 1-2 seeds.
Seed:
Endospermic, with hairy testa.
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Cassia fistula (Amaltas)
Habit:
Ornamental, cultivated tree with beautiful yellow pendulous racemes.
Root:
Highly branched tap root.
Stem:
Aerial, erect, solid, cylindrical, woody and branched.
Leaves:
Ramal, stipulate, stipules small and caducous, alternate, petiolate, compound,
paripinnate, 6-10 leaflets arranged opposite to each other.
Leaflets: Opposite, ovate, entire margin, acute apex, sub sessile with pulvinus at the base,
margin of leaflets slightly wavy, unicostate reticulate, glabrous, leathery when old,
green.
Inflorescence: Long, pendulous raceme, panicle or compound.
Flower:
Bracteates, pedicillate, ebracteolate, irregular, zygomorphic, complete, bisexual,
perigynous, pentamerous in outer three whorls, cyclic, yellow.
Calyx:
5, polysepalous, imbricate, odd sepal anterior, inferior, green or greenish yellow.
Corolla: 5, polypetalous, ascending imbricate, the posterior petal small and innermost in the
bud, postero-lateral petals cover it, ovate, entire, distinctly veined, yellow, inferior.
Androecium: 10, polyandrous, unequal, anterior 3 stamens are long and sickle shaped and bears
fertile anthers with longitudinal dehiscence. The four stamens are medium sized
fertile and bithecous but have dehiscence by apical pores, the three smaller posterior
stamens are sterile and are called as staminodes, anthers basifixed, medium sized
anthers sometimes bend after dehiscence.
Gynoecium: Monocarpellary, ovary superior, slightly stalked, curved, marginal placentation,
short style, terminal and hairy stigma, ovules many.
Fruit:
Cylindrical, indehiscent pod with one seeded transverse compartments.
Seed:
Endospermic
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Acacia arabica (Kikar)
Habit:
Evergreen tree with dark brown bark, grows wild as well as cultivated, xerophytic.
Root:
Branched tap root, deep feeder.
Stem:
Aerial, erect, cylindrical, branched, woody, solid, dark brown, bark secretes a gum
called gum Arabica, stipular spines on stem.
Leaves:
Cauline and ramal, alternate, stipulate, stipules modified into spines, petiolate,
alternate, bipinnate, compound.
Leaflets: Opposite, sub sessile, small, oblong, entire, obtuse, unicostate reticulate, glabrous,
rachis downy with several glands.
Inflorescence: Axillary cymose head, yellow.
Flower:
Bracteate, ebracteolate, sub sessile, regular, actinomorphic, bisexual, hermaphrodite,
cyclic, pentamerous in outer 2 whorls, cyclic, hypogynous small, inconspicuous,
yellow, fragrant.
Calyx:
5, gamosepalous, slightly petaloid, pentafid, campanulate, greenish yellow, inferior,
odd sepal anterior.
Corolla: 5, gamopetalous, tubular, tube twice long than sepals, yellow, inferior.
Androecium: Indefinite, polyandrous, filaments long and conspicuous, exerted anthers small
with stalked glands.Yellowish , anthers bithecous, dorsifixed, longitudinal introrse
dehiscence, pollen grains agglutinated in groups.
Gynoecium: Monocarpellary superior ovary, unilocular marginal placentation, many ovules in
the carpel, ovary sessile, style long filiform, stigma minute, ovary green, bears small
white glands.
Fruit:
Legume, lomentaceous, fleshy pod with 10-12 parts due to sutures deeply indented
between the seeds.
Seeds:
Non-endospermic
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Ocimum basilicum (Niazbo)
Habit:
A tall aromatic, cultivated herb.
Root:
Branched tap root.
Stem:
Aerial, erect, quadrangular, branched, hairy, aromatic, and herbaceous above and
woody below.
Leaves:
Ramal and cauline, opposite and decussate, exstipulate, petiolate, simple, ovate,
serrate margin, apex acute, unicostate reticulate, hairy, herbaceous.
Inflorescence: Raceme of verticillasters.
Flower:
Ebracteate, pedicillate, pedicel small, complete, perfect, irregular, zygomorphic,
hermaphrodite,bilabiate, cyclic, hypogynous,purplish.
Calyx:
5, gamosepalous, tubular, bilabiate upper lip consists of 1 lobe and lower of 4 lobes,
purple,green, hairy, inferior.
Corolla: 5, gamopetalous, bilabiate, upper lip of 4 petals and lower of one petal only (4/1),
light purple, inferior.
Androecium: 4, fifth posterior stamen absent, polyandrous, alternipetalous, didynamous, two
anterolateral are long and two posterolateral are short. Each of these stamens has a
long connective which bears a fertile anther lobe at its posterior end and sterile lobe at
the anterior end. The filaments are small, attached to the long connective near the
sterile end and are versatile in fixation, thus form a lever mechanism, dehiscence
longitudinal introrse, inferior.
Gynoecium: Bicarpellary, syncarpous, ovary superior, deeply 4-lobed, bilocular at first
becoming quadrilocular due to the formation of the false septum, one ovule in each
loculus, axile placentation, a nectariferous disc with an anterior lobe is present below
ovary, style long, gynobasic, stigma bifid.
Fruit:
Schizocarpic, cacerulus, with 4 nutlets.
Seed:
Non-endospermic.
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Helianthus annuus (Sunflower)
Habit: Annual herb with beautiful capitula.
Root: Branched tap root.
Stem: Aerial, erect, cylindrical, branched, herbaceous, solid, hairy, glabrous.
Leaves: cauline and ramal, exstipulate, petiolate, hairy petiole, simple, ovate, margin serrate,
apex acute, alternate or sub opposite, unicostate, reticulate, surface hairy, green.
Inflorescence: yellow racemose head or capitulum, capitulum radiate heteromerous , consisting
of (a)bisexual, tubular, disc florets and (b) Pistillate or neuter,ligulate ray florets, disc florets
occupy the center and ray florets lie at the periphery. The capitulum is surrounded by 3 serie of
green involucre bracts.
(A) Ray Florets: bracteates, sessile, zygomorphic, female or sterile, yellow, tricyclic, epigynous,
incomplete, imperfect.
Calyx: 2-3, free, scale like, superior.
Corolla: 3-5, gamopetalous, ligulate, formed by small basal hairy tube and a large flat strap
shaped and clearly veined limb or strap, entire or 3-5 toothed (indicating no. of petals),
superior, yellow.
Androecium: absent
Gynoecium: may be absent or when present bicarpellary, syncarpous, inferior, unilocular,
basal placentation, ovule single, bifid stigma, hairy and filiform style. Stigma curled and
hairy on the outside.
(B) Disc Florets: bracteates, bracts large, sessile, regular, actinomorphic, bisexual, epigynous,
tetracyclic, tubular, yellowish black.
Calyx: 2or 3 free, reduced scale like, hairy, generally antero-posterior, white, superior.
Corolla: 5, gamopetalous, tubular, tube slightly swollen near the base where nectar is
present, yellow, 5 toothed, teeth black, valvate, superior.
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Androecium: 5, epipetalous, filaments free, short, alternating with the petals, syngenesious
anthers, introrse longitudinal dehiscence, anthersbasifixed with rounded base, bithecous,
superior.
Gynoecium:Bicarpellary, syncarpous, ovary inferior, unilocular with a single basal ovule, style
long, stigma black, bifid, ovary completely sunken in the thalamus whose walls are hairy,
stigma curled back to expose the inner stigmatic surface.
Fruit: An achene, cypsela.
Seed: Non-endospermic.
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PLANT ANATOMY
Internal Structure of Dicot stem
Internal structure of Dicot stem
1. Epidermis consists of parenchymatous cells , single layered, compctly arranged, interrupted by
multicellular hair ,which is the extension of the epidermal cells , it is covered above by the layer
of cuticle, stomata are also prsent at intervals.
2. A few layered collenchymatous hypodermis also follows the epidermis.
3. Few layered parenchymatous co
cortex
rtex follows the hypodermis, it also has oil canals. Cells are
chlorenchymatous and perform photosynthesis too.
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4. Endodermis is single layered having barrel shaped cells without casparian strips. Cells are
composed of single layered parenchyma.
5. Pericycle is heterogenous having both sclerenchymatous and parenchymatous cells.
Sclerenchymatous patch is present opposite to vascular bundles and parechymatous patch is
present in between the two vascular bundles and performs the storage function.
6. Vascular bundles are present in the form of a ring and called as the eustele, the bundles are
conjoint, collateral, endarch and open having well developed pith on the inner side.
7. Pith cells are parenchymatous and are having storage function.
Internal structure of Dicot root
1. Epiblema is single layered made up of compactly arranged thin walled parenchymatous cells.
Due to the presence of root hairs it is also called as piliferous layer. In T.S. cells appears
isodiametric, oval or rectangular. Root hairs are long, tubular, and are unicellular.
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2. Epidermis is followed by cortex which is made up of thin walled cells, cells may enclose
intercellular spaces for diffusion of gases. Cortical cells may be replaced by suberised cells as a
result of secondary growth.
3. Cortex is followed by a single layered endodermis of barrel shaped cells, cells are living and
rich in starch grains, a characteristic band of thickening known as casparian strip is present along
the radial and tangential cells of the young epidermal ce
cells.
4. The layer next to endodermis is pericycle, it is uniseriate and constitutes outer boundary of
vascular cylinder of the roots. It is made of thin walled parenchymatous cells .
5. Vascular tissue is present inner to the pericycle. The root is having alternate and radial
arrangement, primary xylem and phloem appear as separate bundles with the patches of
parenchymatous cells in between the no. Of xylem and phloem strands vary from 2-4.
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6. As the protoxylem elements face towards the periphery, the root is called as exarch.
Internal structure of Nyctanthes arbortristisarbortristis Stem
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The stem of this plant has prominent angles and reveals a quadrangular outline in a transverse
section.
1. Epidermis is single layered parenchymatous with a compact arrangement. The cells are
covered by a continuous layer of thick cuticle. Multicellular hair arise from the epidermal tissue.
2. Cortex is followed by epidermis having a few layered collenchymatous tissue towards outside
and oval, rounded cells on the inner side. The main function of cortex is storage.
3. Endodermis and pericycle are not distinct.
4. normal vascular bundles occur in the center in the form of a ring, the bundles are conjoint,
collateral, endarch and open, in addition to the normal ring of vascular bundles there is present
four inversely oriented vascular bundles in the cortex region at the four corners of the stem.
5. These cortical bundles always get restricted to the four prominent angles of the stem. The
phloem in such bundles is restricted towards the inner side and xylem towards the outer side. The
bundles has the exarch condition.
6. The cambium present in the cortical bundles adds a small amount of secondary vascular tissue
sin a normal manner.
7. The cambium in normal ring in the center also functions in a normal manner and produces
secondary phloem towards outer side and secondary xylem towards inner side.
8. In the center of the stem there is a broad pith which is composed of thin walled cells.
Internal structure of Mirabilis jalapa- Stem
1. Epidermis is made up of single layered compactly arranged parenchymatous cells with no
intercellular spaces. Cells are thin walled, covered with a layer of cuticle on the outer side.
2. Cortex is differentiated to two zones. Below the epidermis is present a zone of
collenchymatous cortex, this occurs in the form of patches,It constitutes 2-4 layers of cells which
are thickened at the corners. Next zone is made up of chlorenchyma cells. This constitutes few
layers of loosely arranged oval or spherical cells. They are rich in chloroplast content and
enclose the small intercellular spaces.
3. Innermost layer of cortex is composed of colorless parenchymatous cells rich in starch content
which is called as endodermis.
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4. Next to endodermis is present one to two
two layers of thin walled parenchymatous cells which
composes pericycle tissue.
5. Large number of scattered bundles are visible in the pith region known as medullary bundles.
Of these only two are larger while others are smaller and are scattered. In ad
addition there is a
normal ring of vascular bundles next to the pith. There are incomplete dwarf bundles in the outer
ring, these contain only phloem.
6. The bundles in the outer ring are complete. They are conjoint, collateral, endarch and open.
7. Medullary
ry bundles are larger and are developed earlier as compared to other bundles which
are smaller in size.
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Internal structure of Boerhaavia diffusa- Stem
1. In transverse section, the stem shows a wavy outline. Outermost layer is epidermis composed
of single layered compactly arranged parenchymatous cells with no intercellular spaces. Many
epidermal cells bear multicellular hair, which are not the outgrowth of epidermal cells.
2. Next to epidermis is cortex which is differentiated into two zones, next to epidermis is
collenchymatous cells, next to collenchyma cells lies the zone of chlorenchyma cells. It is made
up of 4-6 layers of cells. The cells are circular, oval or even polygonal and have abundant
chloroplasts.
3. Innermost layer of cortex constitutes the endodermis. It is clearly distinguishable. It is made
up of thick walled tubular cells with no intercellular spaces.
4. Next to endodermis lie the zone of parenchymatous cells of pericycle which are interrupted
with sclerenchymatous cells in between in the form of patches.
5. Vascular bundles are present in three rings. The outermost ring have 15-20 small bundles, this
ring surrounds a middle ring of 6-14 vascular bundles. These are smaller in size and oval or
rounded in shape. In the innermost ring are present two larger vascular bundles which lie in pith,
these are called das medullary bundles. Of all the bundles these are the largest in size and are
oval in shape. These bundles are fully developed. The central bundles are enveloped in a thin
walled sheath and lie opposite to each other with xylem facing towards the center and phloem
facing outwards. The vascular bundles are conjoint, collateral, endarch and open.
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Internal structure of Dracaena-- Stem
Dracaena is a monocot and as the vascular bundles are closed, the secondary growth does not
occur in monocots, secondary growth in dracaena is regarded as anomalous.
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1. The outermost layer of the stem constitutes epidermis which is made up of rectangular
cells . on the outerside it is covered with a layer of cuticle.
2. Following the epidermis is found a layer of sclerenchymatous hypodermis. The cells of
the ground tissue may or may not enclose intercellular spaces.
3. Numerous vascular tissues lie scattered in the ground tissue. These are arranged in the
form of rings. The bundles in the outer ring are smaller and more in number as compared
to the inner rings.
4. Each vascular bundle is surrounded by a sclerenchymatous bundle sheath. The sheath is
more prominent towards the outerside.
5. Xylem elements are arranged in the form of letter ‘v’. the metaxylem elements occupy
the arms of ‘v’ and protoxylem elements are present at the angle of ‘v’.
6. Small amount of phloem lies between the metaxylem elements, lysogenous cavity is
absent.
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Embryology
Structure of young Anther in Angiosperms
Structure of mature anther in Angiosperms
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A microsporangium is a sporangium that produces spores that give rise to male gametophytes.
Microsporangia are notable in spike mosses, and a minority of ferns. In gymnosperms and
angiosperms (flowering plants), the microsporangia produce the microsporocyte, also known as
the microspore mother cell, which then creates four microspores through meiosis. The
microspores divide to create pollen grains. Structure of anther consists of:
1. A single layer of epidermis between, which becomes stretched and shrivels off at
maturity.
2. A single layer of endothecium. The cells of endothecium possess fibrous thickenings.
They remain thin-walled and constitute stomium (line of dehiscence) in the shallow
groove in between the two microsporangia of the anther lobe
3. One to three middle layers. Cells of these layers generally disintegrate in the mature
anther.
4. A single layer of tapetum. The tapetal cells may be uni-, bi- or multinucleate and possess
dense cytoplasm. The cells of the primary sporogenous layer divide further and give rise
to diploid sporogenous tissue.
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Development of Male gametophyte in angiosperms
Development:
1. Each stamen consists of a lobed anther, containing the microsporangia and supported by a
thin filament.
2. Meiosis of the diploid microspore mother cells in the anther produces four haploid
microspores.
3. Each of these develops into a pollen grain consisting of a larger vegetative cell (also
called the tube cell) inside of which is a smaller germ cell (also called
called the generative
cell).
4. At some point, depending on the species, the germ cell divides by mitosis to produce 2
sperm cells.
5. At the time of pollen dispersal it may be at 2 cell stage or 3 cell stage depending upon
the species.
6. When generative cell divid
divides
es after reaching the stigmatic surface it gives rise to two male
gametes.
7. This structure, a germinated pollen grain carrying two male gametes inside it, is termed
as a mature male gametophyte.
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Structure of Female Gametophyte of angiosperms
Structure of embryo sac/female gametophyte:
1. Embryo sac/female gametophye is an oval structure within an ovule of an angiosperm
that contains the egg. Together with the fertilized egg, it develops into a seed. The upper
end where egg apparatus lies is called as the micropylar
micropylar end from where the pollen tube
enters the ovule.
2. The embryo sac is the female gametophyte of angiosperms, consisting of eight nuclei: the
egg and two adjacent and short-lived
short lived synergids that are near the micropyle .the synergids
are also called potential
ntial cells.
3. Two polar nuclie in the central cell. These fuse with one of the male nucleus to form
primary endosperm nucleus in future, to give rise to endosperm tissue after the syngamy
has taken place.
4. Three antipodal nuclei at the chalazal end of the embryo sac opposite the micropyle. Like
the synergids, these nuclei degenerate at or shortly after fertilization. They pass on all the
nourishment they get from nucellus to the potential egg cell.
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Development of Female gametophyte in Angiosperms
Development:
During megasporogenesis, the diploid megaspore mother cell undergoes meiosis and gives rise
to four haploid nuclei. Angiosperms exhibit three main patterns of megasporogenesis, referred to
as monosporic, bisporic, and tetrasporic In the monosporic pattern, both meiotic divisions are
accompanied by cell plate formation, resulting in four one-nucleate
one nucleate megaspores. Subsequently,
three megaspores, generally the micropylar
micropylar-most megaspores, undergo cell
ll death. In the bisporic
pattern, cell plates form after meiosis I but not meiosis II. The result is two two-nucleate
two
megaspores, one of which degenerates. In the tetrasporic pattern, cell plates fail to form after
both meiotic divisions, resulting in one four-nucleate
nucleate megaspore. Thus, these three patterns give
rise to a single functional megaspore that contains one (monosporic), two (bisporic), or four
(tetrasporic) meiotic nuclei. The monosporic pattern is the most common form and is represented
within the
he Polygonum pattern. During megagametogenesis, the functional megaspore gives rise
to the mature female gametophyte. Initially, the megaspore undergoes mitosis without
cytokinesis, resulting in a multinucleate coenocyte. Subsequently, cell walls form around
arou these
nuclei, resulting in a cellularized female gametophyte. For example, in the Polygonum-type
Polygonum
pattern, a single nucleus undergoes two rounds of mitosis, producing a four-nucleate
four nucleate cell with
two nuclei at each pole. During a third mitosis, phragmoplasts
phragmoplasts and cell plates form between sister
and nonsister nuclei, and soon thereafter, the female gametophyte cells become completely
surrounded by cell walls. During cellularization, two nuclei, one from each pole (the polar
nuclei), migrate toward the center of
of the developing female gametophyte and fuse together either
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before or upon fertilization of the central cell. These events result in a seven
seven-celled structure
consisting of three antipodal cells, one central cell, two synergid cells, and one egg cell . The
monosporic, Polygonum type of female gametophyte is typically a seven-celled
seven celled structure at
maturity.
Types of Ovules in Angiosperms
Orthotropous ovule: the micropylar end, chalazal end and funicle all lie in single vertical line,
also called as a straight ovule. Eg. Polygonum, piper.
Anatropous ovule:: The body of ovule gets inverted at 180 degrees so that micropyle of th
embryo sac comes to lie towards the
the hilum and funicle. Chalazal end occupies the upper end. It
is also called as the inverted ovule. Eg. Solanaceae, compositae.
Hemitropous ovule: The body of ovule gets curved at 90 degrees with respect to funicle,
therefore funicle and micropyle are at 90 degree angle to each other. The embryo sac is placed
transeversely inside the ovule. Eg. Ranunculaceae, crucifers.
Campylotropous ovule: Here the body of the ovule gets curved at an angle, but the embryo sac
remains straight inside it. The micropylar end, and funicle come closer to each other. Eg.
Capsella, mustard
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Amphitropous ovule: Here the body of the ovule as well as the embryo sac gets curved so that
embryo sac attains a horse-shoe
shoe shape. The funicle and micropylar ends are closer to each other.
Eg. Crucifers, papaveraceae.
Circinotropous ovule: Here the funicle of the ovule takes a 360 degree curve so that micropyle
again comes to lie at the upper end. The funicle completely encircles the ovule on all sides so
that it seems like a third integument for
fo the ovule. Eg. Opuntia (cactaceae)
Types of Placentations in angiosperms
The number, type , position and arrangement or the distribution of placentae inside an ovary is
called as placentation.
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Axile : the ovary is partitioned into two or more locules with true septa. Placenta lies in the
center where all the septa meet so that an axile column bearing ovules is formed. Eg. Petunia,
Parietal: two or more longitudinal placentae develop along the wall of a syncarpous pistil. The
number of placentae corresponds to the no. of fusing carpels. The septa formation starts but it
does not reaches the center. Eg. Cucurbitaceae
Marginal: one or two alternate rows of ovules occur longitudinally along the margins of
o the
ovary in the area of fusion of its two margins. A true placenta is believed to be absent. Ovary is
unilocular.it is found in monocarpellary
nocarpellary pistils. Eg. Pea, Cassia, Acacia.
Free central: The pistil is polycarpellary and syncarpous but the ovary is unilocular .The ovules
are borne around a central column, which is not connected with ovary wall
wall by any septum. Eg.
Primula, Silene.
Basal: the ovary is unilocular. It bears a single placenta at the base with generally a single ovule.
The pistil may be monocarpellary or syncarpous. Eg. Ranunculus.
Apical: the ovary is unilocular and bears a single ovule that hangs from the tip of the chamber.
Eg. Cannabis.
Superficial: the ovules develop on the whole inner surface of the ovary including the septa, if
present. It is found in both monocarpellary and syncarpous pistils. Eg. Nymphaea,
Nymphaea Butomus.
297
MORPHO-ECONOMIC NOTES
Solanum tuberosum
Morphology: it is a tuber bearing herbaceous plant. The aerial part of stem is erect in early
stages of growth but later on it becomes more spready.Aerial stem is hollow except nodes.
Adventitious roots produced in groups of three and four at the nodes of main underground stem.
The leaves are 0.3-0.6m long consisting of one terminal leaflet, large lateral, primary oval leaflet
with an entire margin. Leaflets are more or less opposite and are densely hairy at young at
maturity; leaves are spirally arranged on the main stem. Tuber is short greatly enlarged apical
portion of the stem. Moprhologically tuber is shorter and thicker bearing bud or eye. In axil of
scale lies leaf which soon shed bearing their rudimentary leaf scar ridge.
Economic importance: It is used as a main vegetable. Potato can be used in many ways directly
by boiling, steaming, baking, frying, and roasting. It can also be used after processing and
products are potato chips, potato flour,canned potato and dehydrated mashed. In European
countries a large portion of this crop is feeded to livestock. It is good substrate for the growth of
microbes. It is also used at a large scale in many industries and process into starch, glucose,
lactic acid etc. Fresh potato are an important source of vitamin B and C.
298
Helianthus annuus (Sunflower)
Morphology: The stem is aerial, erect, solid, herbaceous and glabrous. Helianthus possesses tap
root system. Inflorescence is capitulum and two types of florets are present – (a) Disc florets and
(b) Ray florets. Many whorls of bracts form an involucre. All flowers ligulate or tubulate or of
both types. Yellow racemose heads or capitulum is present. The sunflower has a rough hairy
stem, broad, coarsely toothed, rough leaves, and auricular head or flower. The leaf and flower
bud show phototropism while the leaf petioles and stem are actively growing.
Economic importance: Sunflower is an important oil seed crop. Sunflower oil is a very
important cooking medium. It can be used in place of ground nut oil, in the place of vanaspati. It
can be safely consumed by the heart patients also. Sunflower oil does not increase the blood
cholesterol levels so can be safely used by heart patients too. Oil is rich in proteins, vit, A, D and
E. The oil is easily digested. Being a semi drying and stable type, sunflower oil is used in making
paints, varnishes, and soaps. Sunflower seed cakes make a nutritious food for cattle, poultry and
cage birds.
299
(
Citrus aurantium (Orange)
Morphology: it is a small tree. It is cultivated in India for its edible fruits and medicinal
properties. Stem is aerial, erect, branched, solid, woody, green and glabrous. Leaves are
evergreen, having winged petiole,a spine is present in the axil of each leaf which is modified first
leaf of the suppressed axillary shoot. Flowers are white in color, and are scented. Fruit is a berry
(Hesperidium) .Seeds are non-endospermic
endospermic and testa are mucilaginous.
Economic Importance: Their fruits are edible. They are enriched with
with vit. C. The leaves yield
an essential oiln known as petrigrain oil (sweet lime) which is used in confectionary and
cosmetics as a flavouring substance. Lemon contains 0.5% sugar and 5% citric acid. Fruits are
eaten raw as well as in pickled form. The juice
juice is used for lemonades and other beverages and as
a flavouring substance, bleaching agent and as a stain remover. The rind is the source of oil of
lemon. Lemon oil is used in perfumery and for toilet soaps.
300
(
Ocimum basilicum (Tulsi)
Morphology: Basil, Thai basil, or sweet basil, is a common name for the culinary herb Ocimum
basilicum of the family Lamiaceae (mints), Ocimum basilicum is a perennial growing to 0.5 m
(1ft 8in) by 0.3 m (1ft) at a fast rate. It is hardy to cold environments and is frost
frost tender. It is in
flower from Aug to September, and the seeds ripen in September. The flowers are hermaphrodite
(have both male and female organs) and are pollinated by Bees.
Economic Importance: Leaves and flowers - raw or cooked. Used as a flavouring or as a
spinach, they are used especially with tomato dishes, pasta sauces, beans, peppers and
aubergines. The leaves are normally used fresh but can also be dried for winter use. A very
pleasant addition
ition to salads, the leaves have a delightful scent of cloves. Use the leaves sparingly
in cooking because the heat concentrates the flavour. A refreshing tea is made from the leaves.
The seed can be eaten on its own or added to bread dough as a flavouring.
flavouring. When soaked in water
it becomes mucilaginous and can be made into a refreshing beverage called 'sherbet tokhum' in
the Mediterranean. An essential oil obtained from the plant is used as food flavouring in
mustards, sauces, vinegars etc. Sweet basil has been
been used for thousands of years as a culinary
301
and medicinal herb. It acts principally on the digestive and nervous systems, easing flatulence,
stomach cramps, colic and indigestion. The leaves and flowering tops are antispasmodic,
aromatic, carminative, and digestive, galactogogue, stomachic and tonic. They are taken
internally in the treatment of feverish illnesses (especially colds and influenza), poor digestion,
nausea, abdominal cramps, gastro-enteritis, migraine, insomnia, depression and exhaustion.
Externally, they are used to treat acne, loss of smell, insect stings, snake bites and skin
infections.
302

BSc.- I Biotech - DAV College Jalandhar

Transcription

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