EarthPoem Archives
Artist/Naturalists
Site Map
Join MorningEarth
Teacher Resources
Learn Ecology
Kids' Earth Art
Members' Writing
John Caddy
Homepage
Contact MorningEarth
 

Biosphere Community

Plant Pages

Pollination and Vegetative Reproduction

  Pollination: All Her Mysterious Ways
 
Pollination by Seasonal Symbiosis
 
A gallery of symbiotic pollinators
 
Pollinator Rewards
 
A Gallery of Nectar Feeders
 
Some Flower Eaters
 
Vegetative Propagation


Pollination: All Her Mysterious Ways

 

Rooted in place, plants must find ways to get their male parts get together with their female parts, and after that they must find ways to disperse their spores and seeds. To pollinate is to carry and deposit pollen (male) onto the stigma (female) of a flower.

Flowering plants rely on pollination to combine their male and female parts. For most plants, this requires help from insects and other animals.

Self-Pollination

A few plants pollinate themselves. Among them are such vegetables as tomatoes and peppers, lettuce, endive, and escarole, and many legumes we grow: peas, green beans, soybeans, lima beans, and cowpeas.

Wind and Water

About 10% of plants use wind or water for pollination. They make lots of pollen and release it to blow or flow away. Aquatic plants release their pollen into water. Most grasses use wind, and such trees as maples, hickory, walnut, butternut, most oaks, pines, firs, and other conifers rely on the breeze as well.

Pollination by Seasonal Symbiosis

Symbiosis with animals is by far the most common method plants use to transfer pollen to others of their species. Some 80% of flowering plants have co-evolved mutual helping relationships with animals in their ecosystems. Most of these animals are insects, but birds and bats are also important local pollinators.

Co-Evolution: Ecological communities are the unit of evolution. Species within these communities evolve in response to one another. Such co-evolution is typical of all ecosystems, and it results in reciprocal relationships. Species within a community need each other; survival depends on system wholeness. This interdependence is most obvious in the seasonal symbiosis between flowers and insects. Great radiations (increase of species) of both flowering plant species and insect species took place in the mid-Cretaceous Period, around 100 million years ago. This great increase in diversity in both groups is the apparent result of pollination symbiosis.

Cross-Pollination is the most common way for plants to accomplish fertilization. It maintains genetic diversity in a population, which increases variation, which in turn makes the community more resilient in the face of disease, attack, and drought. Most plants have evolved ways to avoid self-pollination. Pollen on anthers tends to be held high above the female stigma in the flower center. Timing is often synchronized. Pollen is often ripe and ready before the stigma. Differences within a local population insures that pollinators can still complete their tasks.

A gallery of symbiotic pollinators:

A tiny syrphid fly pollinates yellow hawkweed
photo © John Caddy
A large syrphid fly pollinates an autumn aster
photo © John Caddy

Australian honey opossum pollinates a flower
Photo courtesy Encarta

both bee and butterfly pollinate this buttonbush
photo © John Caddy

honeybee pollinates wild geranium
photo © John Caddy

a drone fly pollinates a high mountain flower
photo © John Caddy
a bat pollinates a night-blooming cactus
Photo credit Merlin D. Tuttle
a gecko about to pollinate a tropical flower
Photo credit National Geographic
hummingbird pollinates in Ecuador
photo credit Wendy Caddy-Stock
three honeybees on huge dogwood flower
photo © John Caddy
bumblebee pollinates milkweed: note the pollen on back leg photo © John Caddy

black bee collects pollen from a daisy
photo © John Caddy


Mayapple being pollinated by a camouflaged moth
Photo credit Charles Pierce
longhorned beetle pollinating wood anemone
photo © John Caddy

clearwing sphinx moth pollinating delphinium
Yucca moths roll pollen threads into balls and carefully stuff them into the stigma to fertilize the yucca flower. Then she lays a few eggs in the ovary where her larvae eat a few of the seeds.
snowberry clearwing moth pollinates milkweed
Photo © John Caddy

hummingbird clearwing moth pollinates a daisy
photo © John Caddy

top of page


Pollinator Rewards

Seasonal Symbiosis is a two-way street. Each participant receives a reward. It is a win/win relationship. The plant is rewarded with reproduction--very basic. The Pollinator is rewarded with food, also very basic. Pollinator rewards are usually nectar, the sweet liquid plants secrete at the base of flowers, but pollen is sometimes a reward as well.

Nectar is depleted every time a pollinator claims its reward. Flowers continually refill their cups, some very quickly. They want happy pollinators. In the case of honey bees, pollinators return to the hive and send others to the same location, so flowers will be visited and revisited. Bumblebees scent-tag visited flowers, so other bumble bees read the tags and pass those flowers by. Happily, those scent tags fade in about three hours, which gives the flowers time to recharge their nectar supply. In many kinds of flowers, nectar production is quite variable. Drought slows nectar making, as do overcast days. But generally nectar is produced throughout flowering, and most copiously when the anthers begin releasing pollen.

A Gallery of Nectar Feeders:

Bumblebee dips her tongue deep into a milkweed flower for nectar
photo © John Caddy

monarch butterfly uncoils its tongue to taste the nectar of sweet joe pye weed
photo © John Caddy

northern pearly eye butterfly drinks nectar
from swamp milkweed flowers
photo © John Caddy

honeybee puts her tongue right down in
the nectar pool of a wild geranium flower
photo © John Caddy

Extra-Floral Nectar: Some plants offer nectar in the seasons without flowers (extra-floral nectar) by secreting nectar in special organs called nectaries, and some plants offer it on leaves and stems without nectaries.They do this for defense. See photos here

Many insects that are not pollinators eat pollen as well as nectar. Some caterpillars and beetles eat the whole flower. Flowers are food for many, not just the human eye.

Flower Eaters


katydid nymph eats high-protein daylily pollen photo © John Caddy

three flower eaters on a goldenglow blossom
photo © John Caddy

longhorned flower beetle eats pollen of wild rose photo © John Caddy

geometer moth caterpillars
eat disk flowers of brown-eyed susan
photo © John Caddy

top of page

Vegetative Propagation

Perennial plants often use asexual (non-sexual) or vegetative propagation. This is a way to reproduce and spread, and also a way to renew youthful vigor. New plants that rise from vegetative reproduction are genetic clones of the mother.

 

Suckers: Many trees and shrubs use root sprouting or suckering. They send out horizontal roots, then produce a signal hormone that makes the root grow buds at intervals. A stem grows from the bud than becomes a sapling tree. Some aspen clone colonies are among the oldest living organisms. Other woody plants that sucker include lilacs, sumacs, willows, cherries, juneberries, persimmon, basswood, Russian olive, and alders. All of these plants form clonal thickets.

section of quaking aspen root
with suckers that are daughter clones

a growing quaking aspen clone: young now,
it could live hundreds of years.
photo © John Caddy


 

Runners, or stolons, are another way plants form thickets of clones. They are stems that run horizontally instead of vertically.  Strawberry stolons run just above the soil surface, and rather like root suckers, form new plants at regular intervals. Some stolons run underground, but they are stems, not roots. Lily of the valley, hawkweed, field bindweed, and many grasses use stolons as a primary means of propagation.

Runners of wild strawberry: nodes every few inches bud roots and leaves photo © John Caddy

lily of the valley clones connected by runners
just under the soil surface photo © John Caddy
 

Rhizomes are yet another way plants produce clonal colonies. Many ferns, such as cinnamon fern and bracken, spread this way, as do wild gingers and some irises. Bamboo produces large stands using rhizomes, as do many grasses and brambles (blackberry, raspberry, wild rose).

a clone of interrupted fern in oak woodland,
each attached to each by rhizomes
photo © John Caddy

"piggyback plant" grows daughters in leaf axils, which drop off to soil and root. The result is a colony of clones. Life tries everything.
photo © John Caddy
 

Bulbs and corms and tubers, although separate botanically, create daughter plants that originate underground. Garden gladiolus and crocus corms produce cormlets that grow and become new plants over time. Bulbs, such as lily bulbs and onions, grow in layers, and many form daughter plants that look like fleshy claws around the bulb.


lily bulb: each clove can form a new plant
gladiolus corm-each bulblet can form a new plant

 

 

top of page

Explore Further in Plant Pages

Plants: What's New? Including Symbiosis with Fungi and Bacteria
Plants: Diversity Major Groups (Images)
Plant Defense including Symbiosis with Wasps
Plant Pollination including Symbiosis with
Insects, Mammals and Birds
Seed Dispersal Including 'Compelled Symbiosis' with Birds, Insects and Mammals