2. reproduction in plants

Give example of fragmentation

spirogyra

Spore formation eg

chlamydomonas

Conidia formation seen in

Penicilium

Eg of gemmule formation in sponges

sycon

purpose of Grafting?

to obtain a hybrid

Essential whorls

androecium and gynoecium

accessory whorls

calyx and corolla

Term for fused calyx and corolla

Perianth and indivisual members are called tepals

Anther

- two lobes (dithecous)

- Four pollen sacs (tetrasporangiate)

Archesporial cell

plant cell that gives rise to sporocyte

What produces pollen grains

sporogenous tissue

1. Epidermis

desc : Tabular (flattened) cell

fnc: Protective layer

2. Endothecium

Desc: Radially elongated cell with fibrous thickenings

Fnc: Dehiscence of anther at maturity

3. Middle layer

Thin walled cells (1-2)

4. Tapetum

Desc: Innermost layer, large cells with dense cytoplasm

fnc: Nutritive layer

microspores

- non-motile, haploid, unicellular body with single nucleus

- two layered wall called sporoderm

- Outer layer (exine) made up of complex, non-biodegradable substance called sporopollenin

- Exine is thin at some places showing thin areas called germ-pores

- inner cell wall (intine) consists of cellulose and pectin

Development of male gamete

Pollen grain undergoes 1st mitotic division to produce a big vegetative and thin walled generative cell which then undergoes 2nd mitotic division resulting in two non-motile male gametes

What is gynoecium divided into

Stigma, style and Ovary

Apocarpous

unfused or free carpels

eg: Michelia

Syncarpous

fused carpels

Eg: Brinjal

Multiovulate

one ovary many ovules

uniovulate

one ovule

Funicle

support, projection and confuction

nucellus

megasporogenesis and development of embryo sac takes place Integuments

integuments

protection to nucellus and embryo sac after fertilization, testa and tegmen is formed (seed coat)

micropyle

A passage for entry of pollen tube. Allows entry of water during germination

Egg apparatus

The egg cell and synergids located at the micropylar end of the female gametophyte, or embryo sac, of angiosperms.

Polar Nuclei

helps in formation of primary endosperm nucleus. Endosperm tissues gives nutrition

Antipodals

Growth and development of the endosperm

Megasporogenesis (BOARDS)

Process of formation of haploid megaspores from diploid megaspore mother cell (mmc)

Development of female gametophyte is __________________ within the megaspore

Endosporous

monosporic development

embryo sac formation from a single megaspore

Autogamy (BOARDS)

Bisexual flower is pollinated by its own pollen grain

eg pisum sativum

Geitonogamy

transfer of pollen grain to a stigma of a different flower on the same plant

eg: Curcubita Maxima

Xenogamy

Type of cross pollination when pollen grain of one flower is deposited on the stigma of a flower of different plant belonging to same species w the help of pollinating agent

chasmogamy (chasmogamous)

when a flower opens to expose its sex organs (*****) Occurs in flowers that are available for a short period of time

Homogamy

When anther and stigma of a flower mature at the same time

cleistogamy

Flowers that self-pollinates before it opens

What flower produces both chasmogamous and cleistogamous flowers?

Commelina

Give examples of Hypohydrophily and Epihydrophily

Hypo: Zostera

Epi: Vallis Neria

Note on pollination by insects (Entomophily)

- Flower is bisexual, protandrous

- Long bifurcated and connected stamen

- Upper branch has fertile anther lobe while the lower has sterile anther lobe

- When the insect enters, it pushes the lower lobe so that the upper lobe brushes with the lower back part of the insect

- When the same insect visits another flower with a mature gynoecium, the receptive stigma picks up the pollen grains

- This is called the salvia lever mechanism

Ornithophily

Pollination by birds

Chiropterophily

Pollination by bats

Outbreeding devices

- unisexuality: Monocious/Dioecious maize. Eg: Mulberry, papaya

- Dichogamy

1. Protandry: Androecium matures first (Sunflower florets)

2. Protogyny: Gynoecium matures before b4 androecium (eg: Gloriosa)

- Prepotency

pollen grains of other flowers germinate rapidly over stigma (eg apple)

- Heterostyly/morphy

Stigma and anthers are places at different levels to prevent pollination

- Herkogamy

Mechanical device to prevent self pollination in bisexual flower. A natural physical barrier is present betn two sex organs to avoid contact of pollen with the stigma of same flower

- self incompatibility (Self sterility)

Genetic mechanism due to which germination of pollen on stigma of same flower is inhibited

eg tobacco, thea

Which part of the flower determines the compatibility of the pollen grain?

Pollen/Pistil

Pollen-pistil interaction

1. Interaction of pollen grains with sporophytic tissue (stigma). It begins with pollination and ends with fertilization
2. The pistil has the ability to recognize and accept the right or compatible pollen of the same species
3. Compatibility and Incompatibility of the pollen pistil is determined by special proteins
4. A physiological mechanism operated to ensure that only an intraspecific pollen germinates successfully.

Entry of the pollen tube through micropyle

POROGAMY

Entry of pollen tube through the Chalaza

CHALAZOGAMY

Entry of pollen tube through integuments

MESOGAMY

What is siphonogamy

When male gametes are carried through a pollen tube viz hollow

Syngamy

Fusion of haploid male gamete with female gamete to give diploid zygote. 2nd male gamete fuses w/ diploid secondary nucleus to form primary endosperm nucleus (PEN) (triploid)

Significance of double fertilization

- Unique feature of angiosperms. Ensures that the parent plant invests a seed with a food store only is the egg is fertilized.
- helps to avoid polyembryony
- Diploid zygote develops into an embryo which develops into a new plant
- Triploid PEN develops into nutritive endosperm tissue
- Restores diploid condition by fusion of haploid male and haploid female gamete

Mosaic endosperm

Endosperm containing tissues of two different types. In plants like corn, the endosperm contains patches of two different colours. It forms a sort of mosaic pattern.

Significance of seed and fruit formation

- Fruits provide nourishment to the developing seeds
- they also protect the seeds in immature condition
- seeds serve as important propagating organs (units) of plants
- seeds and fruits develop spl devices for their disoersal and thus help in distribution of seed

Dormancy

- When a mature and viable seed under a favorable condition fails to germinate, it is said to be dormant.
- Dormancy is said to be a state of metabolic arrest that facilitates the survival of organisms during adverse environmental conditions
- Structural or physiological adaptive mechanism for survival is called dormanc

Parthenocarpy

When a fruit develops without fertilization

Polyembryony

Development of more than one embryo inside the seed

False polyembryony

Involves fusion of two or more nucelli or development of two or more embryo sacs in nucellus

True polyembryony

Additional embryos arise in the embryo either by cleavage of zygote or from synergids or antipodal cells.

Cleavage polyembryony

Zygote proembryo divides into many parts of units

Adventive polyembryony

Embryo develops directly from diploid cell of nucellus and integuments