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AGENCIES OF POLLINATION SMG
- 1. AGENCIES OF POLLINATION Dr Saji Mariam George Associate Professor (Retired) Assumption College Autonomous Changanacherry
- 2. AGENCIES OF POLLINATION Pollination is the transfer of pollen grains(the male reproductive units) from the anther to the stigma (a part of the carpel of the female reproductive organ, gynoecium or pistil )of a flower. • Pollination is essential to effect fertilization and seed formation in higher plants. • Pollination mechanism vary in different types of flowers - occurs by a variety of methods. Some flowers have very special adaptations to ensure pollination. • Biotic and abiotic agents are involved in pollination.
- 3. A few pollen grains on stigma Images Credit : Jawahar Swaminathan https://juridicious.com/2013/03/14/anatomy-of-a-hibiscus-part-2-extreme-macro Hibiscus flower Staminal tube with stamens & Stigma of the flower
- 4. I. Biotic agents - Pollination by animals Zoophily
- 5. ZOOPHILY Entomophily Malacophily Ornithophily Chiropterophily Other Animals Insects Snails, Slugs Birds Bats Rodents Shrews Marsupials Lizards Gecko etc.
- 6. 1. Entomophily • Pollination by insects. • The most common type - much diversity with regard to insect pollinators. Diurnal – bees, flies, butterflies , beetles, wasps, ants etc. ; Nocturnal – moths.
- 7. Insects visit flowers for Nectar (e.g. Thevetia, Thunbergia,Murraya etc.) Edible pollen (e.g. Cassia , Annona, Nymphaea , Clematis, Poppy, Rose etc.) shelter - to lay eggs. Thevetia Thunbergia Murraya Cassia Annona ClematisPoppy
- 8. During visit, the body get dusted with pollen grains on the back (Nototribic pollen transport) underside (Sternotribic pollen transport ) on the flanks(Pleurotribic pollen transport) When the pollen loaded insect visits another flower, its body brushes the pollen to it →Pollination.
- 9. Adaptations in entomophilous flowers Flowers - attractive • Large, showy, conspicuous • Brightly coloured - red, scarlet, blue, yellow etc. – attractive during day. White - conspicuous during night. • Attractive petals / sepals (Mussaenda) / bracts (Bougainvillea , Euphorbia splendens) / stamens - petaloid ( Waterlily- Nymphaea) / Spathe (Musa) • Small , inconspicuous flowers clustered to form an inflorescence. For example, Head inflorescence or Capitulum in Asteraceae (e.g. Sunflower -Helianthus).
- 10. Figs. 1 : Attractively coloured sepals 2 - 4 : Coloured bracts 5 : Coloured spathe 6 : Head inflorescence(Capitulum) -Small flowers clustered to form an inflorescence. . 1. Mussaenda 2. Bougainvillea 3. Euphorbia pulcherrima 4. Euphorbia splendens 5. Musa – Spathe 6. Sunflower – Head inflorescence (Capitulum)
- 11. Fig. 7 : Petaloid stamens of Water lily (Nymphaea) Image credit :Robert Baker , Thomas J. Lemieux , University of Colorado , USA https://botany.org/PlantImages/Conant/CA10-002_1080.jpg
- 12. Some flowers have • scent (e.g. Mimusops, Rose, Jasmine etc.) • strong odour at night (e.g. Cestrum) • unpleasant odour – attracts flies (e.g. Rafflesia – smell of rotten meat; Aristolochia - smell of decaying tobacco etc).
- 13. Flowers with unpleasant odour – e.g. Rafflesia - has smell of rotten meat– attract flies Carrion flies pollinate a Rafflesia Image credit : https://www.travelblog.org Rafflesia (Largest flower)
- 14. Flowers with unpleasant odour e.g. Aristolochia- attract flies Image credit:https://indiabiodiversity.org Aristolochia indica
- 15. • Stigma sticky, rough and catches the pollen grains soon. • Pollen grains rough, sticky, often shows spinous outgrowths (The exine sculpturing)– easily stick to the body of the insects. • Flowers may have pollen kitt-an yellowish, viscous and sticky substance in the exine of pollen grains – hydrophobic lipids containing species-specific carotenoids.
- 16. Pollen grains with spiny exine sculpturing . Pollen kitt
- 17. ENTOMOPHILY Melittophily Myophily Psychophily Phalaenophily Cantharophily Sphecophily Myrmecophily Bees Flies Butterflies Moths Beetles Wasps Ants
- 18. Entomophily: Melittophily – Pollination by Bees- important pollinators. A bee carrying pumpkin pollen Image credit : Anthony BouchardSource: Phys.org https://www.labroots.com Examples of plants pollinated by Bees • Pumpkin • Bean • Cucumber • Tomato • Mango • Onion • Carrot • Olive • Peach • Apple • Citrus • Strawberry • Cherry • Grapes • Blueberry • Sunflower • Daisy • Acacia • Cassia etc.
- 19. Entomophily: Myophily – Pollination by Flies. A hoverfly pollinating a water lily(Nymphaea) Image credit : https://www.lahoregardening.com Examples of plants pollinated by Flies • Capsicum • Amorphophallus • Mangifera • Pepper • Apple • Pear • Strawberry • Cherry • Plum • Apricot • Peach • Raspberry • Carrot • Avocado • Onion • Cocoa tree • Impatiens • Rafflesia • Euphorbia • Water lily etc.
- 20. Entomophily: Psychophily - Pollination by Butterflies Southern Birdwing – Butterfly (Troides minos) on Ixora Image credit : Anoop Santhakumar https://dekochi.com/southern-birdwing.html Examples of plants pollinated by Butterflies • Delonix regia • Caesalpinia pulcherrima • Lantana camara • Asclepias curassavica • Bougainvillea spectabilis • Quisqualis indica • Dianthus • Delphinium • Lily • Gloriosa • Bauhinia • Mussaenda • Stachytarpheta • Aster • Goldenrod • Allium • Cosmos • Verbena • Marigold • Ixora • Calendula • Eupatorium • Zinnia etc.
- 21. Entomophily: Phalaenophily - Pollination by Moths A Manduca moth on a Datura flower Photo : K. Riffel http://nationalmothweek.org Examples of plants pollinated by Moths • Yucca • Datura • White clover • Jasmine • Fuchsia • Dianthus • Evening primrose • Cestrum nocturnum • Quisqualis indica • Ghost orchid • Tobacco • Cashew • Papaya • Verbena etc.
- 22. Entomophily: Cantharophily - Pollination by Beetles Examples of plants pollinated by Beetles • Magnolia • Goldenrod • Sunflower • Spice bush (Lindera sps) • Annona coriacea • Water lily • Acacia • Illicium • Nelumbo etc. Beetles on Magnolia grandiflora flower http://www.wlgf.org
- 23. Entomophily: Sphecophily -Pollination by Wasps Potter wasp on Aster Paper wasp on Goldenrod Images Credit: Beatriz Moisset. https://www.fs.fed.us Examples of plants pollinated by Wasps • Fig • Aster • Goldenrod • Maple • Ivy • Penstemon • Gooseberry • Marigold • Cow pea • White clover • Fennel • Chiloglottis trapeziforms (Australian orchid) etc.
- 24. Entomophily: Myrmecophily - Pollination by Ants Common white-footed ants pollinates rare wild Jamun, Syzygium occidentale . https://binj.in/science/common-ant-pollinates-rare-wild-jamun
- 25. Pollination by Ants… Photos by Beatriz Moisset https://www.fs.fed.us Examples of plants pollinated by Ants • Jatropha curcas • Polygonum cascadense • Conospermum undulatum • Triphysaria pusilla • Euphorbia heterspina ssp. Baringoensis. • Euphorbia seguieriana • Medicago sativa • Melitotus officianalis etc.
- 26. Entomophily: Special mechanisms Yucca flowers & the moth Pronuba yucca-sella • Moth cannot survive without Yucca flower and the plant fails to reproduce sexually without the moth. • Moth drills a hole in the ovary and lay eggs. • Moth collects pollen from several flowers –pushes the pollen towards the stigma → fertilization → seed. • Insect eggs → larvae – feed on developing seeds. Some seeds remain unconsumed → propagate the species.
- 27. Yucca flowers and the moth Pronuba yucca-sella Image credit : https://terra4incognita.files.wordpress.com Image credit : William E. Ferguson https://www.britannica.com
- 28. Pollination of a Yucca flower by Yucca moth Image credits: Joshua Tree National Park. https://www.zmescience.com
- 29. Lever mechanism in Salvia(Lamiaceae) • Corolla - bilabiate – upper lip and lower lip . • 2 protandrous stamens – one lobe fertile and the other sterile – forms a ‘plate’- lies at the mouth of the flower just above the lower lip . • Long connective - fertile lobe away from the ‘plate’ , lie covered under the upper lip.
- 32. • As the bee sits on the lower lip of the Salvia flower and tries to suck nectar, it pushes the sterile ‘plate’ which automatically swings the fertile anther lobe down to touch the back of the bee - get dusted with pollen - when this bee visit another flower → pollination. Photo © Rollin Coville
- 33. Pit fall mechanism (Trap mechanism): Fig (Ficus carica) Fig (Ficus carica) Image credit : blogs.ubc.ca https://laidbackgardener.blog
- 34. • Inflorescence of a Fig – a highly condensed cymose - a hypanthodium (syconium) . • It is a hollow, flask - shaped, fleshy axis opening by a small ostiole at the apex. • Flowers protogynous - arranged on the inner surface - many, unisexual. • Female flowers - at the base. • Male flowers - at the top near the ostiole. • Gall flowers (Sterile flowers) near the opening. Image credit : https://www.biophotosharing.com
- 35. • Fig wasp, Blastophaga enter through ostiole – lays eggs inside “gall flowers”(Sterile flowers). • Eggs → Larvae → wasps. • When crawl out of the inflorescence, brush against the male flowers and get loaded by their pollen grains. • When these pollen - loaded insects visit another inflorescence , pollinate the long – styled female flowers. Fig wasp Image credit : JMK, Wikimedia Commons Image credit: www.naturamediterraneo.com
- 36. Pit fall mechanism (Trap mechanism): Aristolochia • Flower protogynous - long corolla tube – reproductive structures are located in the swollen base of the tube. • Inner surface of the corolla tube is lined with deflexed (bent abruptly downward) hairs. • Flower has the smell of decaying tobacco – attracts insects to the corolla tube – once inside the flower, the insect fails to come out because of the deflexed hairs and during their struggle to come out of the corolla tube , the pollen grains attached to the body are transferred to the stigma effecting pollination.
- 37. • When pollination is over, the anthers dehisce – the body of the insect get dusted with pollen grains. • The deflexed hairs → flaccid, the pollen - loaded insect get out of the tube. • When the insect enters another flower, the pollen grains attached to the body will strike the stigma → pollination.
- 38. Pit fall mechanism (Trap mechanism): Aristolochia https://www2.palomar.edu
- 39. 2. Malacophily • Pollination by snails and slugs – occurs in subterranean runners and creepers which grow closely adhering to soil. Examples of plants pollinated by snails and slugs • Lemna • Limonium • Arisaemia • Colocasia odora • Calla palustris • Chrysanthemum • Volvulopsis nummularium • Rohdea japonica • Philodendron pinnatifidum • Chrysosplenium alternifolium • Phragmipedium caudatum • Ipomoea pes-caprae • Campanula jacobaea • Alocasia etc. Lemna Limonium Arisaemia
- 40. • In Colocasia, the inflorescence is a spadix – the base form a spathal chamber which encloses the flowers. • Snails are attracted by the colour and smell – enter into the spathal chamber – the pollen grains from the male flowers – attach to the body. • When such a snail enters into another inflorescence, pollination may occur . Colocasia esculenta Green female flowers (below) many yellow male flowers Image credit: Sheldon Navie https://keyserver.lucidcentral.org
- 41. 3. Ornithophily • Pollination by birds • Flowers big, brightly coloured(mostly red, orange, purple etc.) and odourless. • Produce large quantities of pollen- sticky - adhere to the body and nectar. • Flowers may be tubular (e.g. Nicotiana glauca),cup shaped (e.g. bottlebrush- Callistemon), urn - shaped (e.g. some members of Ericaceae), funnel shaped etc., loosely clustered on tips of flexible stalks. A hummingbird on Asclepias. https://monarchbutterflygarden.net
- 42. Examples of plants pollinated by Birds • Nicotiana glauca • Callistemon • Bignonia • Butea • Bombax • Fuchsia • Strelitzia • Lobelia • Erythrina • Lantana • Asclepias • Ixora etc.
- 43. 4. Chiropterophily • Pollination by bats • Pollinate plants that open during evening or night - Flowers large, white, yellowish green or brownish or purple coloured, some with a disagreeable scent. • Large number of stamens- pollen produced in large quantity. • Large quantity of nectar. A bat on Banana flowers Photo: Stewart & Dudash. https://www.botany.one
- 44. Examples of plants pollinated by Bats • Musa paradisiaca (Banana/plantain) • Kigelia pinnata (Sausage tree) • Anacardium occidentale • Anthocephalus cadamba • Bauhinia megalandra • Eperua falcata • Mango • Guava • Bread fruit • Agave • Passiflora • Durian • Certain cacti (e.g. Carnegiea gigantea ) etc. Cave Nectar Bat on Durian flowers https://www.merlintuttle.org
- 45. 5. Pollination by other animals • Pollination by squirrels. • Squirrels visit many flowering trees – have some role in pollination. Examples of plants pollinated by squirrels • Melaleuca cajuputi • Helicteres isora • Mucuna macrocarpa • Madhuca species etc. Plantain Squirrel (Callosciurus notatus) on Melaleuca cajuputi (Myrtaceae) https://besgroup.org
- 46. • Pollination by Honey possum(Honey mouse ). • Pollinate Eucalyptus, Banskia, Baobab(Adansonia digitata) etc. Honey possum on Eucalyptus Oxford Scientific / Getty Images https://www.treehugger.com Honey possum on Banskia Kate Boland https://www.worldatlas.com/articles/10-unusual- plant-pollinators-from-the-animal-kingdom.html Baobab flower https://en.wikipedia.org
- 47. • Pollination by Black & white ruffed Lemurs. • Pollinate the Traveler's palm(Ravenala madagascariensis) of Madagascar. Pollination by Black & white ruffed Lemur in Traveler's palm Images : https://www.indefenseofplants.com Inflorescence of Traveler's palm
- 48. • Pollination by Hawaiian night rat. • These rats at night climb to trees to eat the succulent bracts of Freycinetia arborea (climbing screwpine) and while feeding, transfer pollen and thus bring about pollination. Climbing screwpine Daniel Mosquin Image License: Creative Commons License https://botanyphoto.botanicalgarden.ubc.ca Climbing screwpine inflorescence Photograph by: Forest and Kim Starr Useful Tropical Plants Database 2014 by Ken Fern, web interface by Ajna Fern with help from Richard Morris. Creative Commons Attribution 3.0 http://tropical.theferns.info
- 49. • Pollination by Namaqua rock mouse (A rodent) in Pagoda Lily (Massonia bifolia Syn.Whiteheadia bifolia). Namaqua rock mouse pollinating Pagoda Lily Credit: Petra Wester https://phys.org
- 50. • Elephant-shrews, looking similar to mice pollinate Pagoda lily (Massonia bifolia Syn. Whiteheadia bifolia , Asparagaceae), Cytinus visseri (Cytinaceae) etc. A short-snouted elephant shrew pollinating Cytinus visseri flowers. © 2011 The Royal Society https://royalsocietypublishing.org
- 51. • The gliding marsupials, the yellow-bellied glider (Petaurus australis) and the sugar glider (Petaurus breviceps) are involved in pollination of some plants- Eucalyptus, Banskia etc. Yellow-bellied glider on Swamp Mahogany (Eucalyptus robusta) Photo : David Stowe https://publications.rzsnsw.org.au Sugar glider https://en.wiktionary.org
- 52. • Lizards rarely pollinate flowers. • Pollination by Lizards is common on islands. Examples of plants pollinated by Lizards : • Musschia aurea (Campanulaceae) • Phormium tenax (Agavaceae) A Lizard pollinating Musschia aurea (Campanulaceae) D.M. Hansen. Corresponding author: Jens M. Olesen (jens.olesen@biology.au.dk). uploaded by Alfredo Valido https://www.researchgate.net
- 53. • The blue-tailed Gecko (Phelsuma cepediana) is a pollinator of Roussea simplex flower (Family: Rousseaceae) in Mauritius. Gecko pollinating the flower of Roussea simplex http://powo.science.kew.org
- 54. II. Pollination by Abiotic agents 1. Anemophily • Pollination by wind • Anemophily occur in grasses, Coconut palm, Pinus etc. Coconut palm inflorescence © TNAU-2014. http://agritech.tnau.ac.inPinus male cone
- 55. Adaptations in anemophilous flowers • Flowers usually in spikes - Grasses - the inflorescence axis elongates considerably so that the flowers are brought well above the leaves. Pennisetum orientale Image credit : Manoj P Tropical Institute of Ecological Sciences, Kottayam https://indiabiodiversity.org
- 56. • Catkins – Mulberry • Both spikes and catkins swing freely and shake off their pollen grains in air. Catkins in Mulberry https://blog.usejournal.com
- 57. • Flowers are small - Perianth lobes reduced or absent. • Flowers have no attractive colour, scent and nectar. • The stamens have long and slender filaments and exerted - anthers versatile - swing freely on the filament - dispose the pollen in all directions. Versatile anther http://sweetgum.nybg.org Versatile anther of Amaryllis Jonna Saraswathi https://www.flickr.com
- 58. • Stigmas are specially adapted for catching pollen grains - long, feathery and branched (in most grasses) - pollen grains are caught between the branches of stigma. • In Typha the stigma is brush - like. • The stigma usually project outwards – wheat, paddy, maize, sugar cane, palms etc. • Pollen grains are produced in large quantity to compensate their heavy loss during wind transport.
- 59. Long, feathery stigma Corn – Left : Male flower tassel Right: Female flower silk or stigma Image : Tejaswi Kamble https://www.quora.com Image : E. Thralls https://edis.ifas.ufl.edu
- 60. • Winged pollen grains in Pinus - produced in large quantity and are released to air - “Sulphur shower”. Winged pollen grain of Pinus Release of winged pollen grains of Pinus to air “Sulphur shower”
- 61. • In plants with unisexual flowers , male flowers are more numerous than female flowers - Coconut palm (Cocos nucifera). Coconut palm(Cocos nucifera) Spadix inflorescence - Many male flowers and only a few female flowers
- 62. Disadvantages of Anemophily • Pollination is not certain – depends on the direction of wind. • Large quantity of pollen is wasted. • Because of the above reasons, anemophily is primitive.
- 63. 2. HYDROPHILY • Pollination by water • Occurs only in a few water plants- Vallisneria, Elodea, Hydrilla, Zostera, Ceratophyllum, Najas etc. • Most of the aquatic plants bear their flowers above the surface of water and are pollinated by wind or insects.
- 64. Adaptations in hydrophilous flowers • Flowers – small, inconspicuous • Non-essential parts , if present have waxy coating – protects from wetting • Colour, nectar and scent absent • Pollen grains light and sticky – covered with wax. • Stigma – funnel shaped, sticky – prevents wetting.
- 65. Types of Hydrophily 1. Epihydrophily Pollination takes place on surface of water. Eg. Vallisneria Hydrilla Elodea etc. Vallisneria https://www.aquaplante.fr
- 66. Hydrilla Photo : D. F. Spencer. https://wric.ucdavis.edu Hydrilla female flower Photo: Shaun Winterton, Aquarium and Pond Plants of the World, Edition 3, USDA APHIS PPQ, Bugwood.org https://www.invasive.org
- 68. Epihydrophily in Vallisneria • A submerged , dioecious plant. • Flowers are borne under water. • Male flowers – small, shortly stalked – produced in large numbers in spadix inflorescence. • On maturity, the male flowers get detached – float on the surface of water. • Female flowers are solitary – borne on long and coiled stalks. • The mature female flowers rise up to the surface of water by uncoiling the stalk. • Female flower has large, sticky and trifid stigma.
- 69. Vallisneria male flowers floating on the surface of water https://www.indefenseofplants.com
- 70. Vallisneria : Female flower https://www.indefenseofplants.com
- 71. • The detached male flowers cluster around a floating female flower and when the anthers burst , pollen grains get attached to the stigma →Pollination. • Soon, the long stalk of the female flower begins to coil – bring the female flower again below the water level.
- 72. After pollination, the stalk of the female flower coils up, drawing the ripening ovaries under water. https://www.indefenseofplants.com
- 73. 2. Hypohydrophily • Pollination takes place completely under water. Examples: • Zostera • Ceratophyllum • Najas etc. Zostera Ceratophyllum Najas
- 74. Hypohydrophily in Zostera • A marine submerged angiosperm , known as eel grass - perennial herbs. • Leaves - 110 cm long. • Inflorescence - a flattened spadix with flowers on one side, all enclosed within a spathe, spadix linear; monoecious, staminate flowers 1 -20; pistillate flowers 1 - 20.
- 75. • Pollen grains are very long , needle / thread-like / filamentous , without an exine. • The styles erect from the spadix - Stigma long , exposed . • When the pollen grains reach the stigma, it coils around the stigma and results in pollination.
- 76. Zostera….
- 77. Zostera…. A. Reproductive shoots B. Pollen dispersal by water Photo: Dr. J. Ackerman, University of Guelph, Canada https://www.vcbio.science.ru.nl
- 78. Hypohydrophily in Ceratophyllum • A submerged water plant , known as Coontail, Hornwort etc. • The stem 1- 3m with numerous side shoots . • The leaves in whorls of six to twelve, each leaf 8 - 40mm long, simple, or forked into two to eight thread-like segments edged with spiny teeth - stiff and brittle. • Tiny, submersed flowers at the leaf bases - monoecious . The petals are tiny green scales. The male flowers occur in pairs on opposite sides of the stem while the female flowers are solitary. Male flowers of Ceratophyllum https://www.minnesotawildflowers.info
- 79. • Each male flower has a number of stamens - mature anthers get detached at the base , float on the surface of water – dehisce - liberate pollen grains - round with no exine. • Pistillate flowers: ovary tapering to persistent, spine like style. The pollen grains when come in contact with the long and sticky stigma of the female flower → Pollination.
- 80. THANK YOU
Editor's Notes
- 1. Spiny pollen 2 . Pollen kitt
- Conferva (Plural Confervae) – a former name for any of various thread like green algae esp. a genus Tribonema found chiefly in fresh water.