L earning Objective 7

I. ANIMAL POLLINATORS.

A. Pollination by animals occurs when animals are displaying behavior related to food foraging, especially for nectar.

Nectar is a sugar water produced by nectary glands which are found at the base of many flowers. Its primary function is to "reward" the animal pollinator.

B. Co-evolution (the genetic changing of two or more organisms in response to each other) helps to explain the closely-matched characteristics found between the flowering plant and its pollinator or pollinating agent.

A striking example is the orchid from Madagascar, called the Star of Bethelem (Angraecum sesquipedale). It has a very long pouch at the base of the flower in which nectar is found. Long ago Darwin made a prediction that a moth with a 12 inch proboscis (long curled tongues of pollinating moths and butterflies) would be found as pollinator. Indeed, much later, such a moth was found to be the pollinator.

C. Pollination by bees:

1. There are about 20,000 different species worldwide.

2. They depend on nectar and pollen for food.

3. They are attracted to bright colors, primarily to yellow and blue. They cannot see true red as a bright color - it appears as a dull color to them.

4. They can see ultra-violet radiation which we cannot.

a. Many flowers have lines or distinctive markings called "honey guides" some of which are invisible to us, but not to bees.

b. Some "honey guides" are visible to human eyes under ultra-violet illumination.

5. Bees can detect odor. Typically bee-pollinated flowers have a delicate, sweet fragrance.

D. Pollination by moths and butterflies:

1. Moths and butterflies can detect odors; therefore, often the flowers they pollinate are sweetly fragrant.

2. Butterflies perceive many bright colors.

3. Moth-pollinated flowers are usually white or yellow, colors which stand out under low illumination (as at night). These flowers usually have a heavy, distinctive fragrance.

 

Koki'o ke'oke'o

Examples are the white ginger (Hedychium coronarium) and a native white hibiscus, such as Koki'o ke'oke'o, (Hibiscus arnottianus).

E. Fly-pollination:

Fly-pollinated flowers are fleshy, reddish in color, and have a rotten meat-like odor! Stapelia gigantea or Carrion flower is an example.

F. Bat-pollination:

Bat-pollinated flowers are often dull in color, large, and hang down on long stems from trees as found in the dead rat or sausage tree (Kigelia pinnata)

  G. Bird-pollination:

1. Bird-pollinated flowers are usually large, bright red or yellow in color with little odor since birds often do not have developed sense of smell.

2. Copious production of nectar in these flowers keep up with high energy needs of the bird. Examples: include Hibiscadelphus distans, hau kuahiwi.

3. Hummingbirds (not native to Hawaii) typically pollinate red tubular flowers.

Example: firecracker flower (Russelia equisetiformis).

4. Honey creepers (endemic birds of Hawaii) pollinate flowers which are usually large, colorful, and often red.

Ususally these flowers have a characteristic twisted, or curved corolla (the structure of the petals) which fits the curved beak of the bird.

I'iwi in koli'i  

Examples are 'Ohi'a lehua, many native hibiscus and native lobelioids (plants in the Lobelia family) like
koli'i Trematolobelia macrostachys)

 

H. Beetle pollination:

1. Beetles have little color or scent perception. Flowers they pollinate are typically small, whitish-green, with little odor.

2. They are frequent pollinators of native plants of Hawaii because they make up much of the native insect population.

A. Water pollination:

1. Pollen floats on water from one flower to another.

2. This type of pollination is uncommon in Hawaii where there are few natural lakes or perennial streams.

B. Wind pollination:

1. Wind pollination is more common. It involves massive production of many small flowers, often lacking petals. (Why? Petals primarily attract animal pollinators.)

2. These flowers produce large amounts of pollen and have prominent and branched stigmas (Why? To catch windborne pollen). Grasses and pine trees are prime examples.

A. Social bees (like honey bees) are not native to Hawaii and there are few butterflies or moths.

H. arnottianus

1. As a result, conspicuous, fragrant yellow or blue flowers and white, fragrant night bloomers are rare in the native flora. One exception is a native, fragrant, white hibiscus (H. arnottianus).

Manono

2. Small beetles are numerous and many native plants have small,greenish-white flowers which are beetle or small insect-pollinated.

Apapane in 'ohia

3. There are a number of flowers, commonly red and conspicuous, which are pollinated by the native honey creeper birds. However, many of these birds are endangered, their numbers are low and many are extinct which also puts the bird-pollinated plants at risk of also being endangered.

B. As a result there is a significant lack of large and bright-colored native Hawaiian flowers unlike what occurs in most warm climatic regions of the world.