The Science Book

104

See also: Carl Linnaeus 74–75 ■ Charles Darwin 142–49 ■

Gregor Mendel 166–71 ■ Thomas Hunt Morgan 224–25

I

n the mid-18th century, Swedish

botanist Carl Linnaeus realized

that flower parts parallel the

reproductive organs of animals.

Forty years later, a German

botanist called Christian Sprengel

figured out how insects played a

major role in the pollination, and

so fertilization, of flowering plants.

Mutual benefit

In the summer of 1787, Sprengel

noticed insects visiting open

flowers to feed on the nectar inside.

He began to wonder whether the

nectar was being “advertised”

by the petals’ special color and

pattern, and deduced that the

insects were being enticed onto

the flowers so that pollen from the

stamen (male part) of one flower

stuck to the insect and was carried

to the pistil (female part) of another

flower. The insect’s reward was a

drink of energy-rich nectar.

Sprengel discovered that some

flowering plants, if they lack color

and scent, rely on wind to disperse

their pollen. He also observed that

many flowers contain both male

and female parts, and that in these,

the parts mature at different times,

preventing self-fertilization.

Published in 1793, Sprengel’s

work was largely underappreciated

during his lifetime. However,

it was finally given due credit

when Charles Darwin used it as

a springboard for his own studies

on the coevolution of flowering

plants and the particular species

of insects that pollinate them and

ensure cross-fertilization—to their

mutual benefit. ■

THE MYSTERY OF NATURE

IN THE STRUCTURE AND

FERTILIZATION OF FLOWERS

CHRISTIAN SPRENGEL (1750–1816)

IN CONTEXT

BRANCH

Biology

BEFORE

1694 German botanist

Rudolph Camerarius shows

that flowers carry a plant’s

reproductive parts.

1753 Carl Linnaeus publishes

Species Plantarum, devising a

classification system guided

by flower structure.

1760s Josef Gottlieb Kölreuter,

a German botanist, proves

that pollen grains are needed

to fertilize a flower.

AFTER

1831 Scottish botanist Robert

Brown describes how pollen

grains germinate on a flower’s

stigma (female part).

1862 Charles Darwin

publishes Fertilisation of

Orchids, a detailed study

of the relationship between

flowers and pollinating insects.

A honeybee lands on the sexual parts

displayed at the center of these brightly

colored petals. Honeybees account for

80 percent of all insect pollination and

pollinate a third of all food crops.