Plant Lec: Pollination

Pollination syndromes

-Pollen grains are variable across groups of plants but similar within groups

• One can identify pollen to a family, but difficult to identify pollen to species

Exile

Tough protein coat that surrounds the few cells within the pollen grain

Cross pollination and Self pollination

-Cross pollination creates seeds that are genetically more diverse, and this is beneficial to the parent plant

-Self pollination has advantageous, like when individual plants arrive in a new habitat, the plant can reproduce with itself

• Makes these plants better colonizers

How did the first plants disperse spores

-Very first plants dispersed spores (progenitors of pollen) by the wind

-Suggests wind may have been ancestral form of pollen dispersal

Wind pollination

-Today, many species of plants are dispersed by wind

-Share several traits, like lack petals, so less attractive to animals than other types of flowers

-Also lack fragrances

-Pollen is dry, light weight, not nutritious, and particulate (not sticky)

-Grass stamens usually produce large amounts of pollen

Plants that are wind pollinated commonality

-Very common, such as grasses or pines

-This is due to massive amounts of pollen insures pollination

-During few days each spring, plants can fill air with pollen

Animal pollination

-Animal pollination usually involves showy petals and strong fragrances

-These kind of plants can be rare due to the pollinator seeking out other members of the species to gather pollen and/or nectar

Origin of animal pollination

-Origin can be seen in plants as early as mosses

-Angiosperms, only plants with flowers and first to be pollinated by animals, originated in Cretaceous

• So did pollinators like bees

Bee pollination

-Bees gather nectar and pollen

-Pollen is sticky and bees are “hairy” so a lot of pollen sticks to them

-Pollen is also nutritious, unlike pollen of wind-dispersed plants

-Bees groom themselves to gather the pollen and then place it into special pollen baskets on hind legs

• Bees have a crop in thorax to hold nectar

-Back in hive, bees store pollen and nectar in combs

Bee flowers

-Very diverse, and so are bees

-These flowers have nectaries deep inside

-Often have nectar guides to help bees find nectar, makes bees more efficient

-Tend to be purple but can be a variety of colors

• Bees see flowers differently than humans

-Bees can see ultraviolet light and the nectar guides are sometimes invisible to us, but visible to bees

Bees and used flowers?

-Bees often avoid flowers that has been recently visited by another insect and removed the nectar

-Studies show bees can detect the electric charge on flower

• Bee’s antennae can detect the charge (static electricity) of a flower

• Use charge to avoid flowers

Can beetles and flies pollinate plants

-Yes, some can

-These plants are usually more open and often smell like rotten meat

Erisimum

-Produces symmetrical and slightly asymmetrical flowers

-Beatles prefer asymmetrical flowers, which could explain low zygomorphic flowerers

Fly pollinators

-Flowers often have strong, musty smells, or smells like rotten meat.

-Some flies have long mouth parts to reach nectar deep inside flowers

Pollinations and flowers coevolution

-Pollinators and flowers have coevolved, so extreme cases the flower ant be pollinated by animals other than coevolved pollinator

Proboscis

What some insects use to reach the nectaries deep within the flower

Yucca moths and yuccas

-One of few pollinators that pollinate on purpose

-Yucca moths gather pollen mass and place it on stigma of different plant

-Lay eggs on ovary wall

-Larvae will bore into fruit and eat developing seeds

-Female moths ensure young will have food

How can a gene determine which animals show up to pollinate flower

-YUP gene (yellow upper) was swapped

-This shifted pollinator visitation rates, and suggested a few genes control flower traits that attract pollinators

-Pollinator switch has been a common phenomenon

Bat flower

-Smell musky, an odor bats like

-Doesn’t have to be colorful cuz bats don’t see color in dark

-Robust flowers

-Flowers produced at margins of plants for easy access