Daisy Family

The daisy family (Asteraceae) is the earths largest flowering family with over 23,000 species and considered one of the most advanced in flora evolution, many plants you will be familiar with, from the obvious daisy varieties to all thistles and dandelions, to less obvious ones like Yarrow, Burdock and pineapple weed. Look a little closer though and you will start to see the similarities which make up this amazing family.

Oxeye Daisy Leucanthemum vulgare on a field boundary
Lesser Burdock Arctium minus
Mugwort Artemisia vulgaris in the foreground

To understand what makes them all a little unique to other families let us first take a moment to understand the components that make up a single flower. Around the outside there would of course be a series of petals, in the middle contains the stamen, the male part of which there can be many. These consist of a long filament with an anther at the end which holds the pollen. Directly in the centre is the Pistil which is the female part. From above you will first see the stigma which is the opening to the style which extends down to the ovary, which contains the ovule. It is this ovule which after fertilisation turns into a seed. All these components form just one flower.

A drawing showing the components of a flower

The flowering plants within the daisy family play a very deceptive roll in not only fooling us, but chiefly the insects they rely on for their pollination and the continuation of their species. They do this by fooling the insects into thinking it is just one flower with a massive cache of nectar in the centre of the flowerhead, when in fact it is full of very tiny flowers known as florets, deceiving the insects that they have hit the jackpot!

Sunflower with individual disc florets seen very clearly here

In the daisy family these individual florets may have both stamen and ovary together, ovary only, stamen only or be sterile. In the photo above it shows the impressive size of a sunflower which helps us to clearly see with the naked eye the individual florets in the centre, looking like lots of mini flowers tightly packed together. In the case of the sunflower the florets are made of tiny 5 petaled flowers each with its own stamen and pistil, which when pollinated turns into the sunflower seed.

Sunfflower, Fibonacci sequence

Above you can see the pattern the arrangement of the disc florets make. This is known as the Fibonacci sequence. In understanding this further studies have revealed one in five sunflowers don’t follow this sequence or are even more complicated than we first thought. this pattern can be seen in other areas of nature like pine cones.

Oxeye Daisy Leucanthemum vulgare home to many insects

Each of the individual tiny flowers that are in the centre are known as disc florets, but it doesn’t stop there! In a clever twist the parts of the flower that look like petals around the outside, fooling the insects that it is just one big flower are also florets, as they are around the outside edge, they are known as ray florets.

Oxeye Daisy Leucanthemum vulgare dissected to reveal individual disc and ray florets
A closer look under magnification at the ray and disc florets of an Oxeye Daisy Leucanthemum vulgare

In a common daisy below (Bellis Perennis) there are approximately 150 disc florets and 50 ray florets, that is 200 mini flowers on a flower measuring just 16-25mm across!

Daisy Bellis perennis 200 mini flowers!

Each member of the daisy family can have both types of florets and indeed only one. These types of flowers are known as a composite flower head which is where the old family reference of Compositae is from, now known as Asteraceae. In the case of an oxeye-daisy it has both disc and ray florets, with a dandelion it only has ray florets and thistles only have disc florets.

Oxeye Daisy Leucanthemum vulgare with both disc and ray florets
Dandelion Taraxacum agg with only ray florets, showing its basal rosette leaf structure
Pineappleweed Matricaria discoidea has only disc florets

There are other family characteristics that many species in this family have, from growing their leaves in basal rosettes, as seen in the dandilion above. This is where the leaves come from a central spot radiating out in all directions. A milky latex sap can be seen in many species when the stem or leaf is cut. This is not to be confused with the toxic euphorbia family. Finally, the seeds in the daisy family are commonly connected to a fluffy parachute which is known as a pappus, to help with wind dispersal. Think of a dandelion head and blowing it to tell the time as a child.

Fluffy seed head of a dandelion
Here you can clearly see the feathery parachute known as a pappus
Here you can see the flowerhead or receptacle where they were all located

Next time you are out take a closer look under magnification you can even use your zoom on a smartphone and this whole world of tiny flowers will be revealed before your very eyes.

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