Get complete information on Special Modes of Reproduction

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i. Cases where propagation without the act of fertilization.

ii. Apomixis: The term opomixis was given by Winkler in 1908. Development without fertilization of fusion of gametes e.g., Citrus.

iii. Agamospermy: Formation of seeds without fertilization.

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iv. Parthenogenesis: Formation of embryo from an unfertilized egg.

v. Parthenocarpy (coined by F. Nou, 1902): Development of fruit without pollination and fertilizaton. e.g., Pineapple, grapes, apple, pear and banana.

vi. Sporophytic budding: Sometimes takes place in the nucellus and integuments, resulting in the development of an embryo, e.g., orange, opuntia, mango and onion.

vii.Polyembryony: Development of more than one embryos in the same seed ; discovered by Leeuwenhoeck (1719) in citrus; quite common in Citrus and Pinus.

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Some Important Facts :

Allergenic:

Pollen grains of many plants including Parthenium, Chenopoclium, Prosopis, Sorghum, Amaranthus are allergenic.

Palynology:

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Study of pollen grains.

Myrmacophily:

Pollination by ants e.g., many members of family Rubiaceae.

Hay fever:

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Due to allergic reaction due to the presence of pollen in air.

Lever mechanism or Turn pipe mechanism:

Pollination in the members of family Labiatae e.g., Salvia (sage flower).

Flytrap mechanism:

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Aristolochia.

Trap door mechanism:

Present in hypanthodium inflorescence of Ficus species which receives Blastophaga for laying eggs and pollination. This is an example of mutualism.

Largest pollen tube:

Zea mays. In Calotropis and orchids pollen is packed in potlinia (massulae).

Absence of endosperm (double fertilization in angiosperms):

3 families e.g., Orchidaceae, Podostemonaceae and Trapaceae.

Size of pollen-Longest:

Zostera (filamentous without exine) = 2500 ┬Ám.

– Biggest-Mirabilis diameter 250 mm

– Smallest-Myosotis, 2.5-3.5 jam

Panmictic:

Plant reproducting asexually.

Apomictic:

Plant multiplying parthenogenetically.

Amphimictic:

Plant reproducing sexually.

Erythrina:

Pollinated by crows as well as squirrels.

P. Maheswari:

Great plant embryologist of India, wrote a book “An Introduction to the Embryology of Angiosperms”.

G.B. Amici (1824):

First to observe pollen tube in Portulaca.

Hanstein (1868, 1870):

First to study early development of embryo.

S. Miller:

Reported importance of coconut milk in tissue culture.

Guha and Maheswari:

Obtained pollen and anther culture embryos from family Solanaceae.

Piston mechanism of pollination:

White Centaurea.

Edible pollen:

Rosa, Magnolia, Clematis.

Translator type pollinia:

Family Asclepiadaceae.

Sporopollenin:

Present in exine of pollen and preserved during fossilization as it is resistant to decomposition.

Prepotency:

In many plants the pollen grains form a flower when present on the stigma of another genetically different flower germinate more quickly as compared to the pollen grains of the same flower so, help in cross pollination e.g., Grape, pear and apple.

Primrose:

Two type of flowers based on the length of styles.

Pollinium:

In Calotropis and orchids, the pollen of each anther lobe form a sac likemass called pollinium. Each of which is provided with a stalk called caudicle and a sticky base called disc or corpusculum.

Biotransforniation/culture products:

Plant product can be more easily obtained from tissue culture e.g., Shikonin (Lithospermum erythrorhizon), taxol (Taxus brevifolia), digoxin (Digitalis lanata), ajmnalicin (Catharanthus roseus).

Wetraore and Wardlaw:

Successfully cultured shoot tips of pteridophytes e.g., Selaginella, Equisetum and ferns.

Embryo sac:

Monosporic is Polygonum; bisporic in Allium and tetrasporic in Peperomia.

Heteromorphism:

A single species with flowers of different forms. The length of stamen and style varies in these flowers e.g., Linum ussitatissimum and Primula.

Cleavage polyembryony:

Cleavage of the zygote or proembryo e.g., in Orchidaceae family.

Adventive embryony:

Formation of several embryos due to the ‘budding’ or proliferation of the cells of the nucellus or integuments.

In Bryophyllum, plantlets develop along the margin of intact leaves.

Gynogenic haploids:

Possible from unpollinated ovules.

Rudolph Camerarius (1694):

First to describe sexual reproduction in plants.

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