POLLINATION OF FLOWERS 
677 
spring upward, and little puffs of pollen are 
projected into the air. 
Flowers Pollinated by Water. — Flowers 
pollinated by the agency of water are com¬ 
paratively rare. There are, however, four 
common species, two growing in salt water 
and two in fresh water, which deserve men¬ 
tion. The two maritime species are ditch 
grass ( Buppia maritima ) and eel grass 
(Zostera marina), both of which are very 
abundant in shallow streams and bays 
along the eastern coast. The two fresh¬ 
water forms are wateiweed ( Elodea cana¬ 
densis) and tape grass (Vallisneria spiral¬ 
is), which grow in ponds and canals thru- 
out much of eastern North America. Tape 
grass is also called “wild celery” because it 
is the favorite food of the canvasback duck. 
The pollination of tape grass and water- 
weed is so very remarkable that it must be 
briefly described. The flowers are dioeci¬ 
ous, that is, the staminate and pistillate 
flowers grow on different plants. Both 
kinds of flowers are formed under water 
near the base of the plants. The pistillate 
rise to the surface, upon which they float, 
anchored by a long thread-like stem. The 
staminate flowers while still in bud break 
away from their stems, and rise to the sur¬ 
face, where they float about like little boats. 
Presently they expand; and when they 
drift against a pistillate flower the anthers 
come in contact with the broad leaf-like 
stigmas and pollinate them. Then the fer¬ 
tile flower is again drawn down into the 
water by the spiral coiling of its stem, 
where its fruit is matured. 
Flowers Pollinated by Birds. —Bird-flow¬ 
ers are flowers pollinated chiefly or wholly 
by birds, as the cardinal flower, trumpet 
honeysuckle, and torch lily. A typical 
bird-flower is the trumpet flower ( Tecoma 
radicans), a woody vine, which creeps 
over trees and bushes in the woodlands of 
the South and bears scarlet, trumpet¬ 
shaped flowers, two and a half inches 
long, which are often visited by humming 
birds. There are three families of birds 
which are adapted to flower-pollination, the 
humming birds, or Trochilidae; the sun- 
birds or Neetariniidae; and the honey- 
suckers or Meliphagidae. The humming 
birds are confined to North and South 
America; the sun-birds to Africa and In¬ 
dia; and the honeysuckers to Australia. 
In the eastern United States the ruby 
throated humming bird is the only species 
of humming bird. The number of humming 
bird flowers in this area is small, the most 
familiar examples being -the trumpet hon¬ 
eysuckle, the cardinal flower, the trumpet 
flower, the painted cup, Carolina pinkroot, 
and the wild columbine. In the western 
United States some 15 species of humming 
birds are known. But they are most abun¬ 
dant in tropical America where more than 
400 kinds have been described. In Brazil 
they are on the wing thruout the year, and 
Fritz Mueller thought that they visited 
most flowers. The bill is very long, in one 
species exceeding the length of the head 
and body taken together. The extensile 
tongue consists of two hollow cylinders or 
tubes, which can be thrust far out of the 
beak and draw the nectar out of long tubu¬ 
lar flowers. Humming birds have the habits 
of insects and are often mistaken for hawk- 
moths, as they dart swiftly from flower to 
flower. They were first attracted to flow¬ 
ers, not by nectar, but by insects which 
feed on nectar; and altlio they have be¬ 
come fond of sweets their diet still con¬ 
sists largely of insects. The pollen is car¬ 
ried on the short feathers at the base of the 
bill. As the birds poise on the wing in 
sucking nectar, bird-flowers do not have 
alighting or resting platforms. 
Bird-flowers are usually bright red or 
scarlet-colored. It would be easy to enum¬ 
erate more than fifty species of common 
bird-flowers, which display bright red hues. 
It seems, therefore, probable that these col¬ 
ors attract the attention of nectar-sucking 
birds. In Europe, where there are no hum¬ 
ming birds and consequently no native 
bird-flowers, scarlet colors are noticeably 
absent. 
Flowers Pollinated by Insects .—It is es¬ 
timated that there have been described in 
the world up to the present time 132,584 
different kinds of flowers. Kerner places 
the number of species pollinated by the 
wind at about 10,000; but this, undoubt¬ 
edly, is an underestimate. Even if it is 
twice that number, there must be over 100,- 
000 flowers which are regularly or occasion¬ 
ally visited by insects, or are self-pollinated, 
