THE INTIMATE
WORLD OF
FLOWERS
Welcome to the secret world of flowers!
All these striking flowers with intense colours, amazing forms
and wonderful scents. What is their purpose? Are they here
for our pleasure? Just like animals, plants need to ”mate” or
reproduce in order for life to continue. Reproduction in plants
takes place in the flowers, right before our eyes, and is called
pollination. In other words, plants make flowers for their own
benefit. In this pamphlet you can read fascinating descriptions
about the pollination of plants and the help they get from the
wind and insects to ensure successful reproduction.
3
Indicators in the text and signs in the gardens
Plants whose pollination is described in more detail are
marked with the common blue butterfly, both in the text and
the flower beds, making them easy to spot. The plants have
been chosen so that each example of pollination can be seen
on some flowering plant regardless of when you visit during
the season.
Sp, Su, A. These letters are placed after the species name
and indicate the time of the year when the plant flowers.
Sp = SpringSu = SummerA = Autumn
4.2.C - Figures and characters placed after the plant name in
the text, refer to the garden beds in the Systematic Garden at
Fredriksdal. Finally, there is a map showing the location of the
beds in the gardens.
Flora’s Temple is situated in the heart of the Systematic Garden. Here you can find more information about the Botanical
Gardens at Fredriksdal, where the natural flora of the region
Skåne is displayed.
4
contentS
Plants as sexual beingssid 6
Flowers need “a helping hand” in the sexual act
sid 7
Butterflies as pollination aidssid 9
Butterfliessid 10
Mothssid 13
Hymenopterans (bees, bumblebees and wasps) as pollination aids sid 14
Beetles as pollination aidssid 21
Flies and mosquitoes as pollination aids sid 22
The wind and insects work for free in the service of humans
sid 24
5
Plants as sexual beings
Plants generally have open flowers, where male and female reproductive organs can
be easily viewed. Most plants are hermaphrodites and have both male and female
reproductive organs on one and the same flower. The male reproductive organs, called
stamens, are topped by anthers bearing pollen. The female reproductive organ, the
pistil, comprises the ovary, style and stigma.
Plants with clearly visible reproductive organs
Lily-of-the-valley (Sp) – Covallaria majalis 5.3.B
Crane’s-bill (Su) – Geranium sp. 3.1.B
Suffolk lungwort (Sp) – Pulmonaria obscura 2.1.B
Bluebells (Su) – Campanula sp. 1.4.C
Wood sorrel (Sp) – Oxalis acetosella 3.2.B
Mullein (Su, A) – Verbascum sp. 1.3.C.
Pollination involves the transfer of pollen from the stamen to the stigma of the pistil.
This normally takes place within one and the same species, but between one individual
and another.
Fertilisation occurs when the male nucleus of the pollen grain fuses with the egg cell
(ovum) in the ovary of the pistil. After some time fruits are formed, containing seeds
which are the offspring of the plant. More information about this process can be found
at Freja Frö, an exhibition with wood sculptures in the Systematic Garden at Fredriksdal.
Linnaeus was the first to consider plants as sexual beings. He compared the structure of
flowers to human relationships when he placed plants in classes and orders according
to the number of stamens and pistils they had. It was often a matter of one woman (the
pistil) living in a relationship with many men (the stamens). In the Systematic Garden,
there is a specific garden bed where plants are displayed according to Linnaeus’s sexual
system.
6
Pollination
Stigma
Stamen
Ovary
Style
Flowers need “a helping hand” in the sexual act
How is pollen transferred from the stamen to the pistil? Flowers seldom manage to
reproduce on their own accord, but require help during the sexual act. In order for the
offspring to obtain as wide a genetic variation as possible, pollen should preferably be
transferred from one plant to another within the same species. Some plants make use of
the wind.
Relying on the wind to transport pollen grains is somewhat risky since “the wind blows
wherever it pleases”. Plants pollinated by wind, therefore, produce an enormous amount
of pollen. This applies to many of our trees, which facilitate pollination by flowering
early in the spring before they put out leaves. The pollen grains are then easily dispersed through the air without leaves to obstruct their passage. The great quantities of pollen often cause people to develop allergies to, for instance, hazel, alder, elm and birch.
Grasses (Sp, Su) – Poaceae 5.1.B and Mugwort (Su, A) – Artemisia vulgaris 1.2.C, are
other examples of allergy-inducing plants pollinated by wind. The stamens often hang
far out of the flowers on slender filaments, so that the pollen is easily caught by the
wind. In other words, it is vast quantities of male gametes (sperm cells) that cause the
problems in people’s respiratory passages. Has anyone ever thought about that? These
gametes have ended up in the wrong place altogether, where they have no use and just
cause problems.
7
The stamens on grass inflorescences dangle on long filaments
to enable the wind to catch the pollen grains
A more reliable way for plants to be pollinated is by employing insects to transfer the
pollen from one flower to another when it clings to their bodies. The insects do not
actively take part in the sexual act, but find themselves in the flower in search of food.
Offering insects something edible is one way for plants to ensure pollination. The
food consists of protein-rich pollen and nectar containing carbohydrates in the form of
sugars. In order for insects to find their way to the food, plants have developed big, eyecatching flowers with beautiful colours, exciting shapes and wonderful scents. Insects
see the world differently to us. They have the ability to detect ultraviolet light and can
therefore see patterns in the flowers where the human eye cannot. Most of the scents
are there so that the insects will remember them and associate them with food. In some
cases flowers attract insects through the use of scents that resemble something else that
the insect might be looking for, such as rotten meat or amorous females ready to mate.
Plants and insects have developed and adapted to each other over millions of years.
However, some flowers are not particularly specialised. They are open with nectar that
is fairly accessible for visitors, can be pollinated by widely diverse groups of insects, and
generally offer pollen as the reward. In other cases, flowers are pollinated by specific
insects. The reward for these insects is often nectar, well hidden deep within the flower.
8
Some plants are able to self-pollinate, where pollination takes place within one and the
same flower. Self-pollinating plants often have small, insignificant flowers that lack scent
and do not produce nectar or pollen in any great amount. The advantage of this method is that offspring are guaranteed without the investment of extra resources, but at
the cost of genetic variation. Should the environment change in any way, these plants
have a poor ability to adapt to the new environment since all plants within the species
are similar. Many self-pollinating plants are annuals and can quickly colonise bare earth.
Plants with self-pollinating flowers
Chickweed (Sp, Su, A) – Stellaria media 4.2.C
Smooth rupturewort (Su) – Herniaria glabra 4.2.B
Butterflies as pollination aids
Butterflies as a group are divided into butterflies and moths, and the flowers that they
visit differ in form and scent. Butterflies do not gather food for their offspring, but
consume all nourishment themselves. They sip nectar with the help of a proboscis, a
long tubular sucking organ that is rolled up under the head when not in use. A flower
typically visited by butterflies has nectar stored deep within a floral tube or spur. Butterflies can exploit many different types of flowers, but certain flowers are pollinated
only by butterflies.
A flower typically visited by moths
9
Butterflies
Flowers pollinated by butterflies often have weak scents and reddish colours. Butterflies
are, in fact, the only insects able to see red hues. The flowers are often upright with a
flat top that functions as a landing site. This is necessary since butterflies are stationary
while feeding on nectar. Many flowers have such long floral spurs that only the long
proboscis of a butterfly can reach the nectar. The plant clearly marks the path to the
nectar with dots, lines or furrows on the petals of the flower.
Red campion (Sp) – Silene dioica 4.2.C.
Red campion has unisexual flowers on separate male and female plants (dioecious).
Some plants have flowers bearing only stamens, others only pistils. The female flowers
differ from the male flowers in that they have a swollen calyx containing the ovary
where the seeds are formed. Most animals have separate sexes, but among plants this is
unusual. A design with separate male and female plants prevents self-pollination.
Red campion
Female plant with swollen calyx containing the ovary.
10
Male plant
Cowslip (Sp) – Primula veris 2.4.D
Cowslip is pollinated by butterflies with long proboscides, able to reach the nectar
stored deep within the flower. This plant bears two types of flowers: the style is long and
the stamens short on the one, and vice versa on the other. An insect visiting a flower
with a short style will collect pollen from the long stamens. When the insect then visits
a flower with a long style, the stigma is placed at the right height to enable pollen from
the previous flower to be rubbed off onto it. At the same time the butterfly is powdered
with pollen from the short stamens, which can then be transferred to flowers with short
styles. Also have a look at Cowslip, Bird’s-eye primrose, and Primrose in the garden
beds. They too have flowers constructed this way.
Primrose
Flower with short style
Flower with long style
11
Forget-me-not (Sp, Su) – Myosotis sp 2.2.B
There are several different species of Forget-me-not. All of them have lovely, sky-blue
flowers. The flower is flat and functions as a landing site for butterflies that wish to sip
nectar from deep within the flower. Showing the way is a wreath of yellow or white hairs
in the centre of the flower, forming a ring around the entrance to the floral tube. This
also functions as a water-repellent cover over the anthers. In this way the entrance is
partly covered, making it possible only for butterflies with long proboscides to reach the
nectar. Pollen clings to them while they sip nectar and can thus be transferred onto the
next flower.
Forget-me-not with a wreath of hair in the centre of
the flower showing the way to the nectar.
Examples of other flowers pollinated by butterflies
Ragged-robin (Sp, Su) – Lychnis flos-cuculi 4.2.C
Maiden pink (Su) – Dianthus deltoides 4.2.C
Corncockle (Su) – Agrostemma githago 4.2.C
Bloody crane’s-bill (Su) – Geranium sanguineum 3.1.B
12
Moths
Flowers typically visited by moths are open at night. They are often pale in colour
or completely white, and their scent is strongest during dusk and dawn, and at night.
Moths have a well-developed sense of smell located on their antennae. They hover in
mid air - especially hawk moths - while feeding on nectar, often located deep within the
flower in floral tubes or spurs. These flowers, therefore, do not need a landing site.
Honeysuckle (Su) – Lonicera periclymenum 1.4.A
Honeysuckle only starts spreading its scent in the evening, when moths become active.
The flower has a fairly slender, deep floral tube. The nectar available at its base can only
be reached by large moths with very long proboscides.
Examples of other plants pollinated by moths
Lily-of-the-valley (Sp) – Covallaria majalis 5.3.B
Nottingham catchfly (Su, A) – Silene nutans 4.2.C
Suffolk lungwort (Sp) – Pulmonaria obscura 2.1.B
Evening-primrose (Su, A) – Oenothera biennis 2.3.C
Valerian (Su) – Valeriana officinalis 1.4.B
White campion (Su, A) – Silene latifolia 4.2.C
Soapwort (Su, A) – Saponaria officinalis 4.2.C
13
Hymenopterans (bees, bumblebees and wasps) as pollination aids
Hymenopterans pollinate more kinds of flowers than all the other insect groups put
together. Pollen clings easily to their hairy bodies. Hymenopterans prefer flowers with
yellow and blue colours and are able to open up flowers that are closed. They often find
nectar with the help of streaks and spots. Their mouthparts are shorter than those of
butterflies, and many of them have flat tongues, meaning that they can only lap nectar,
not suck it up.
Bees and bumblebees are important pollinators of the large flowering plants within the
following plant families: the mint family – Lamiaceae 2.1.B, 2.1.C, the legume family –
Fabaceae 3.2.B, 3.2.C, 3.2.D, 3.4.C, 3.4.C, and the figwort family – Scrophulariaceae
1.3.B, 1.3.C. From an economical perspective, bees and bumblebees are the most important pollinators in that they pollinate fruit trees and berry bushes. Their significance
lies in the fact that they do not only gather nectar and pollen for themselves, but also
for their larvae, meaning that they must visit a great number of flowers.
Bees are best at remembering flower shapes. They are also able to inform one another
of good sites for food collection and areas with good flower populations.
Wasps are chiefly predators and feed their larvae mostly on animal matter. They do,
however, visit flowers, especially at the end of the growth season in search of energyrich nectar.
Flower typically pollinated
by bumblebees and bees.
14
Foxgloves (Su, A) – Digitalis purpurea 1.3.C
Foxgloves are specially designed to suit bumblebees. Speckles on the fused petals,
called a corolla tube, show the way to the nectar inside the flower. When the bumblebee crawls into the flower, pollen is gathered on its back. Bees are not able to enter the
flower because they use their wings to propel themselves forward, and the cramped
space of the corolla tube prevents this. Foxgloves have a long flowering season and
individual flowers in the inflorescence open from the bottom up. In each flower the
stamens develop before the pistil. This is well adapted to the behaviour of bumblebees,
since they always start at the bottom of the inflorescence and make their way upwards.
This reduces the risk of the flower self-pollinating. Bumblebees have good memories;
they can remember flower shapes and good collecting sites for several days, ensuring
pollination of the flowers.
Foxglove
Young plantMature plant
15
Foxglove
Upper section of the flower removed.
The flower in the male phase.
The flower in the female phase.
Common toadflax (Su, A) – Linaria vulgaris 1.3.C
Toadflax has a flower that is specialised for pollination by bees and bumblebees. The
flower is closed and can only be opened by insects with great strength. The nectar
is contained at the bottom of a long, narrow floral tube, and only certain species of
bumblebees and bees have sufficiently long proboscides to reach it. A kink on the lower
lip of the flower has a darker yellow colour than the rest of the flower and functions as a
guide to the location of the nectar.
Common bird’s-foot trefoil (Su) – Lotus corniculatus 3.2.D
All the flowers of leguminous plants have a specific structure. They consist of four different parts: a standard petal (vexillum), two wing petals and a keel petal. The standard
bears the markings that show the insect where to land. In the bird’s-foot trefoil the wings
curve over the keel like a saddle and when an insect that is heavy enough lands on the
wings, both the wings and the keel are depressed. The pressure causes a ribbon of pollen to be squeezed from an opening at the tip of the keel and to attach to the underside
of the insect’s body. After some time the pistil matures and the stigma pushes through
the tip of the keel, where it can receive pollen from visits made to other flowers.
16
Leguminous flower with standard, wings and keel.
Standard
Wing
Wing
Keel
Common bird’s-foot trefoil. Longitudinal section through the keel.
In a state of rest.
After the keel has been
depressed and the pollen
squeezed out.
The pistil has pushed its way out.
Example of another leguminous plant that is pollinated in a similar way
Field restharrow (Su, A) – Ononis spinosa ssp. arvensis 3.2.B
17
Western marsh-orchid (Sp) – Dactylorhiza majalis 4.3.A, 4.4.A
Marsh-orchids, like all other orchids in Sweden, are protected by law. The lower petal
functions as a landing site for, primarily, bees and bumblebees. The impact of colour is
amplified by the large number of flowers gathered together on one inflorescence. The
pattern of spots on the landing site leads to the centre of the flower. Once there, the
insect triggers a mechanism causing the single stamen to release the two pollinia, each a
waxy mass of pollen grains. Each pollinium has a sticky adhesive pad (viscidium), which
adheres to the insect’s head. The two pollinia stand erect at first, like two horns on the
insect, but within the course of half a minute they bend 90 degrees so that they point
forwards instead. When the insect visits the next flower, the pollinia are positioned in a
way that enables them to make contact with the stigma.
Bee with pollinium attached to its head.
Pollinium
Pollinium
At the moment of adherence.
30 seconds later.
Fly orchid (Sp) – Ophrys insectifera 4.3.A, 4.4.A
This orchid has flowers that look and smell like female members of the Sphecidae wasps
who are ready to mate. The likeness is so great that males land on the flowers in the
belief that they are female wasps. The flower has hairs that correspond to those of a
female wasp, making it possible for the male to orientate himself correctly on the flower
and carry out the motions of mating. At the same time the pollinia adhere to the insect
and are carried along to the next flower.
Broad-leaved helleborine (Su) – Epipactis helleborine 4.3.A, 4.4.A
Broad-leaved helleborine is an orchid primarily pollinated by wasps, but bees and bumblebees are also frequent visitors to the flowers. The lower lip (labellum) of the flower
functions as a landing site and while sitting there the insect can feed on the rich nectar,
18
collected in a cup (hypochile) further in on the lip. Located above the nectar cup are
the stigma and the two pollinia. While a wasp feeds on the nectar, the sticky adhesive
pads of the pollinia adhere to the insect’s face - on the antennae, mouthparts or eyes.
The nectar is toxic and the soon intoxicated insect becomes unable to remove the pollinia from its face. The wasp’s ability to fly is reduced and it therefore stays longer on the
same inflorescence, crawling from flower to flower. Pollination increases as a result. The
wasps become addicted to the toxic liquid and return readily to new flowers of helleborine in the days that follow.
Purple loosestrife (Su, A) – Lythrum salicaria 2.3.C
Purple loosestrife is usually pollinated by bumblebees and bees, but also by other
insects. Like primroses, its stamens and pistils come in different lengths on different
flowers in order to encourage cross-pollination. But here the flowers are even more refined. There are three different kinds of flowers and three different lengths of stamens
and pistils, distributed in different ways in each of the three types of flower. Pollination
only takes place between stamens and pistils of the same length.
Purple loosestrife
Medium length style Long style
Short style
Notice the three different lengths of the stamens and pistils. The arrows demonstrate possible pollen transfer.
Oxeye daisy (Su) – Leucanthemum vulgare 1.2.C
The oxeye daisy attempts to deceive insects into seeing it as a single large flower, but in
reality it comprises many small flowers collected into a disc-shaped inflorescence. Each
disc attracts bees, bumblebees and hoverflies, but even butterflies and beetles pollinate
these flowers. The chief purpose of the petal-like ray florets is for display. In some cases
they are completely sterile, in other cases they bear only pistils. The tubular flowers or
19
disc florets in the centre of the inflorescence are bisexual. The stamens form a fused
tube around the style. The stamens mature before the pistil, already when the flower is
still in bud form. After that the style shoots up through the stamen tube. This reduces
the risk of self-pollination. The nectar is located further down in the tubular corolla and
is easily reached by insects.
Oxeye daisy
Composite flower head
Bisexual tubular disc floret with stamens and pistil.
Female ray floret with pistil.
Many others plants in the composite flower family have the
same flower structure and are pollinated in similar ways
Common daisy (Sp, Su, A) – Bellis perennis 1.1.B
Scentless mayweed (Su, A) – Tripleurospermum perforatum 1.2.C
Mountain arnica (Su) – Arnica montana 1.2.B
Yellow chamomile (Su, A) – Anthemis tinctoria 1.2.C
Common ragwort (Su, A) – Senecio jacobaea 1.2.B
20
Beetles as pollination aids
Beetles are clumsy insects. Flowers suitable for pollination by beetles must therefore
have a big enough surface for the beetles to land on, such as members of the
umbelliferous family – Apiaceae 2.3.B, 2.4.B, 2.4.A and
the buttercup family
– Ranuncualceae 4.1.B. Beetles are attracted more by scent than by form and colour.
Their mouthparts are short and best adapted for chewing, and they readily eat pollen.
If they feed on nectar it must be within easy reach in flat, open flowers. The flowers
visited by beetles can also be pollinated by a number of other insects. It is rare to find
flowers that are specialised for pollination by beetles.
Flower typically pollinated by beetles
21
Flies and mosquitoes as pollination aids
Flies visit simply designed flowers that are open and flat, with nectar and pollen within
easy reach. The flowers are often white, yellow, or greenish in colour and they often
emit unpleasant odours. Larger flies and mosquitoes have relatively long proboscides
with which they can suck nectar from tubular flowers. Some flies and mosquitoes are
attracted to flowers that smell like carrion or urine when they are in search of suitable
places to lay their eggs.
Wild chervil (Sp) – Anthriscus sylvestris 2.3.B and other umbelliferous flowers
Members belonging to the family of umbelliferous plants have flowers that are clustered into umbrella-like inflorescences. This mass effect makes it easier for insects to
find them. The flowers are flat and open, and the nectar is easily accessible. Hoverflies
and other flies with short proboscides often pollinate this plant family; approaching the
flowers can set off a whole cloud of flies. Hoverflies resemble bees and wasps, but their
pattern of movement is different and they can hover in the same spot for long periods.
Lords-and-Ladies (Sp) – Arum maculatum 5.1.C
Moth flies are attracted by the stench of urine emitted by the spadix and land on the
inside of the white leaf-like spathe. They lose their grip and slide into the floral chamber
in the interior of the flower. If the moth flies are carrying pollen from previous visits to
other flowers, the female flowers at the base of the spadix will be pollinated. The moth
flies are unable to escape since the wall of the floral chamber is smooth and slippery,
and the opening is blocked by hairs. The male flowers, positioned above the female
flowers on the spadix, mature after a day. The hairs wither and the surface of the chamber wall becomes rough, enabling the moth flies to make their way out, their bodies
loaded with pollen. Then, hopefully, a new stench of urine attracts them again and the
whole story repeats itself. The odour lures the moth flies into thinking they have found
cow manure in which to lay their eggs.
22
Lords-and-ladies
Hairs
Male flowers
Female flowers
Birthwort (Su) – Aristolochia clematitis 4.4.B
Like that of Lords-and-ladies, this flower is also designed as a trap for insects. The flies
are lead down a tube to the nectar at the base of the flower. If the flies are carrying
pollen, the pistils get pollinated at the same time. Hairs pointing downwards prevent the
insect from getting out. After pollination the hairs wither, the male flowers mature and
new pollen clings to the fly on its way out.
Birthwort
23
The wind and insects work for free in the service of humans
Linnaeus was the first to understand the significance of the role played by insects in the
balance existing between different plant and animal groups. According to him, no other
animal group is more crucial to maintaining this balance than insects.
The wind and insects aid pollination by transferring the pollen from one flower to
another. They are essential to the world economy because they pollinate plants of
great value to people. The wind is important, for instance, for maize and all other crops
cultivated for the production of cereal grains. Insects assist us in vegetable cultivation which produces matured fruits like tomatoes and cucumbers, but also in all fruit
farming. Without their help there would be no apples, cherries, oranges, almonds or
currants. These insects provide us with invaluable, free services and we should do everything within our power to make sure that they thrive in nature and in our gardens.
In recent years the decline of many insect populations has attracted much attention.
For centuries, the diversity of small habitats created by traditional farming methods
has resulted in favourable conditions for insects as a group. The shift to more efficient
cultivation systems and large-scale production has had a serious impact on the number
of insects. Edge habitats have disappeared, inorganic fertilisers have reduced diversity
and hayfields and pastures rich in floral diversity have been converted into commercially managed fields and forests. Fredriksdal’s fields and pastures are managed using
traditional farming methods. No pesticides or inorganic fertilisers are used and the fields
are cut annually using scythes or sickle mowers. There is a great biological diversity to
be found here in terms of herbs, grasses, fungi and insects.
In the Systematic Garden at Fredriksdal there is an Insect Hotel that serves as a shelter
for many pollinating insects. Predatory insects that prey on undesirable insects in our
gardens and other cultivations, can also find shelter in our hotel.
By planting nectar-producing plants in your garden, you will help to ensure that many
different insects are able to survive and continue pollinating our gardens.
24
1.1.C
1.1.B
1.2.C
1.2.B
1.1.A
1.2.A
1.3.A
1.4.A
1.3.B
1.3.C
2.1.C
1.4.B
1.4.C
2.2.C
2.1.B
2.2.B
2.1.A
2.2.A
2.3.A
2.4.A
2.3.B
2.3.C
3.1.C
2.4.D
2.4.B
2.4.C
3.2.C
3.1.B
3.1.A
3.2.A
3.3.A
3.4.A
3.3.B
3.3.C
4.1.C
6.1.B
6.2.A
6.2.B
6.1.C
6.1.D
6.2.C
6.2.D
6.3.A
6.3.B
6.4.A
6.4.B
6.3.C
6.3.D
6.4.C
6.4.D
3.2.D
3.4.B
3.4.C
4.2.C
4.1.B
6.1.A
3.2.B
4.2.B
5.1.C
5.2.C
5.1.B
5.2.B
4.1.A
4.2.A
5.1.A
5.2.A
4.3.A
4.4.A
5.3.A
5.4.A
4.3.B
4.3.C
4.4.B
4.4.C
5.3.B
5.3.C
5.4.B
5.4.C
25
Text: Karin Hjelmér
Illustrations: Liselotte Nilsson, Marie Widén
Fact checking: Lars Pettersson, researcher at the Department of Biology, Lund University
Layout: Caroline Flindt
Translation into English: Gayle Rolando
A big thank you goes to the students of the Individual Programme at the school Nicolaiskolan, in
Helsingborg, for their work in creating the wire art butterflies.
With financial support from Hervid Vallin’s Memorial Fund.
26