Reproductive Biology of Trees Pollination Wind-Pollination Syndrome

Reproductive Biology of Trees Pollination Wind-pollination Syndrome • Morphology – Small, insignificant flowers – Lack nectar, bright colors & odor – Pollen production>>>ovule production – Spatial separation of stamens and pistils – Flowers open before leaf production • Common in Temperate; infreq. in tropics • Why? – Good long distance dispersal – Few tree species—easy to find mate – Fewer pollinating insects Wind-pollination Syndrome • Morphology – Small, insignificant flowers – Lack nectar, bright colors & odor – Pollen production>>>ovule production – Spatial separation of stamens and pistils – Flowers open before leaf production • Common in Temperate; infreq. In tropics • Why? – Good long distance dispersal – Few tree species—easy to find mate – Fewer pollinating insects Wind-pollination Syndrome • Monoecy—separate staminate and pistillate flowers on same plant – Frequent on wind-pollinated trees Add photo of Quercus – Quercus, Fagus, Juglans, Carya, Betula, Corylus, Carpinus, Ostrya – Special cases: • Andromonoecy-perfect and staminate flowers on same plant • Gynomonoecy Wind-pollination Syndrome • Dioecy—separate staminate and pistillate flowers on same plant – Wind-pollinated taxa include Salix, Populus, Fraxinus, some Acer, and Ginkgo – Special cases • Androdioecy—plants with staminate flowers and other plants with hermaphroditic flowers • Gynodioecy female male Tropical vs Temperate Tree Pollination • Tropical • Temperate – Specialized flowers – Generalized flowers – Animal pollinated – Wind pollinated – Low density – Dominant tree species populations – Phenology divergence – Phenology similar – Dioecy common – Monoecy and hermaphroditism common Animal Pollination Syndrome • Morphology – Large, colorful flowers – Nectar guides, tactile, olfactory, visual – High quality pollination – Mechanical & biochemical mechanisms of encouraging outcrossing – Temperate examples: Catalpa, Liriodendron, Aesculus, Robinia, Tilia (often members of abundant tropical families) – 95% of tropical trees—bats, birds, insects – Insects in temperate zone Cercis Magnolia Prunus Tilia Robinia Polygamomonoecy in Aesculus Plant with male, female, and hermaphroditic flowers http://earthfriendlygardening.wordpress.com Abundance of Staminate Flowers increase overall attractiveness of floral display increase reproductive output by siring more seeds on other plants Pistillate flowers positioned basally to be close to carbohydrate resources forhttp://earthfriendlygardening.wordpress.com seed development increase outcrossing by matching natural movement of pollinators. Insect Pollination of Catalpa & Kalmia Specialized pollination —insects of specific size and mass required Insect Pollination of Sambucus & Viburnum, Cornus Generalize flowers that attract beetles, flies, bees, and butterflies. Soil pollinators with pollen. Viburnum lantanoides Large sterile flowers on outside of floral display Unusual Sex Expression in Striped Maple • Sex Expression in Acer pensylvanicum – 4% monoecious; 96% dioecious – Male to female; 1:8 – 10% of trees change sex and usually to female – Female trees appear less vigorous and have high mortality • As understory tree, striped maples on verge of death invest heavily in fruit production http://williamcullina.com/Page58.html Triploid Bananas and Parthenocarpy—fruit production without seeds Seedless fruits, sometimes pollination is necessary; fertilization is not. Cacao (Theobroma cacao) Cauliflory Avocados (Persea americana) Protogyny Group A plants Group B plants Sexual Secrets of Figs • Important wildlife fruit in many tropical forests— ‖Keystone Species‖ • Tight relationship with wasp pollinators • Flowers hidden within flasks ―syconia‖— Pollination of Figs Female wasp travels to fig Searching for suitable flowers (i.e., short-styled flowers) for egg laying. Sisson, R.F. 1970. The wasp that plays cupid to a fig. National Geographic 138:690. Fig Pollination Ostiole Short-styled Female Male Female Caprifig—female flowers Flowers are parasitized by wasps; Caprifig is the ―pollenizer‖; male flower development is timed to the life cycle of the wasp. Syconium I Caprifig is unedible—crunchy, Caprifig-unedible fibrous, seedy Sexual Secrets of Figs • Wingless males develop prior to females; • Males mate with females prior to female emergence; • Males die in the only home that they have known. Sisson, R.F. 1970. The wasp that plays cupid to a fig. National Geographic 138:690. Sexual Secrets of Figs Female with caprifig pollen Edible Fig—receives pollen as female wasp travels looking for other fig syconia. Long-styled Long-styled flowers in edible fig prohibit Female egg laying, but female wasp completes Flowers pollination. Pollination of Calimyrna Figs Bags of pollinator- Caprifigs are placed in orchard. Orchard of female edible figs. Calimyrna and Black Mission Figs Black Mission Figs are PARTHENOCARPIC and don’t require pollination for fruit production Calimyrna figs require pollination of long-styled pistillate flowers Ostiole in syconia to produce edible fruits Papaya Products • Latex from young fruits is a source of papain – Meat tenderizer – Shrink resistant wool – Contact lens cleaner – Dietary supplement – Spinal disk removal Sexuality of Papaya Male plants produce more flowers with abundant pollen Female plant—pollination is necessary for fruit production Papaya--GMOs • Selection for cultivars that produce fruits with fewer seeds; • Genetic modification with genes promoting parthenocarpy. • Why have males around?.

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