Distribution and adaptability

Dandelions are incredibly common, growing in meadows, gardens, cracks in the pavement, and almost anywhere with enough soil for them to establish themselves.  They’re adaptable and brilliant at colonizing new environments.  They grow fast.  However, they’re not great at competing against other plants, unless the area they grow in is repeatedly mown or damaged.

They can handle being mown because, unlike many wildflowers, they have really long tap roots.  When a mower destroys the plant above ground, dandelions can re-grow from the submerged root.  This re-growth happens long before other wildflowers can begin again, germinating and emerging as seedlings.

Dandelion plant showing tap root

Dandelion flowers: Ray florets and the Asteraceae

One of the things that makes dandelions so beautiful is their vivid bright colour.  Slightly paler on the outer edges, they are often off-set by verdant grass, and really glow.

Dandelion flowering head

Dandelions are members of the Asteraceae family, they are composite flowers.  This means that every yellow “petal” you see is actually a flower in it’s own right, complete with miniscucle reproductive structures.

If you look at a daisy (another composite flower) with a hand lens, you can see little yellow disc florets (which make up the central yellow part) and white ray florets which encircle it.  The whole assemblage of flowers is called the capitulum and is held within tiers of involucral bracts, which serve the same protective purpose as sepals and the calyx.

Daisy florets: Ray and disc types.

Unlike many Asteraceae

Unlike many members of the Asteraceae, Dandelions do not have disc florets, only ray florets with the one long, distinctive ligule.  Get a magnifier and look closely.  You’ll be able to see the tiny stamens in each and every one.

Ray floret and close up of the stamens and reproductive structure.

Dandelion involucral bracts

Dandelion buds are beautiful things.  Compact and slightly square, they are neatly encased in the involcural bracts.  these are sometimes called phyllaries, or tegules.  Below the capitulum there are leafier bracts, arranged in two rows.

Dandelion bud

The involucral bracts are really important for species identification.  Sometimes they have glands or are striped.  Those of dandelions have slightly darker tips.  They remain after the flower has wilted, encasing the structure until the seeds emerges as the instantly recognizable dandelion clock.

Dandelion flower after wilting and before becoming a seed head.

Dandelion seed heads

One of the most familiar things about dandelions is their beautiful spherical seed heads, sometimes called clocks. Telling the time with a dandelion clock  is much a part of growing up as plucking daisy petals and saying “loves me, loves me not”, or playing conkers.  How many blows does it take until every seed is dispersed?  That’s what time it is.

Dandelion seed head

Their little brown seeds, known as achenes, are attached to the remains of the capitulum at the centre of the structure.  The globe is created by the umbrellas of fluff, or pappas, that are held erect on a stalk above each seed.

Dandelion clock with most of the seeds dispersed

Dandelion seeds

Each seed is carried by the breeze, on a windy day they can travel 5 or 6 miles.  According to the Smithsonian, some are recorded as having travelled 500 miles!  Seeds are viable for several years, although most will be dead within 5 years (Garden organic).  Each flowering head produces about 400 seeds, so over one season, a lone dandelion plant could make several thousand of them.  With a 90% germination rate, that’s impressive.

Dandelion seeds

This dispersal, viability, and the sheer numbers of seeds helps explain why dandelions appear on every continent but Antarctica.

Dandelion leaves

The leaves of dandelion are lobed.  They have pointed side teeth, not neccesarilly opposite each other, which vary in size.  In most cases they have a larger terminal lobe.

Dandelion leaf

Leaf shape is enormously variable in dandelions, both within species (more of which later) and within one plant.  Each dandelion species, and each individual plant, has a distinct leaf shape that it replicates, but this alters as the season progresses.  Botanists identify dandelions early in the year, relying on the outermost (oldest, and first emerging) leaves as a guide.

Pencil dandelion leaf

Environmental conditions affect the leaves.  They tend to be simpler in shaded conditions, and may even be undivided.  Leaves grown in arid conditions, or where there is lots of mowing and high foot traffic tend to have a more complicated pattern of teeth.  Leaves that grow later in the season tend to be more complex shapes, although, as mentioned above, they are still based on the same blueprint.  These late leaves may have much larger terminal lobes.

Dandelion leaf study

The teeth of the leaves explain the etymology of the name.  Dandelion comes from the French, “Dent de Lion” or Lion’s teeth.  The bastardization is easy to see.

Asexual reproduction and dandelions

Almost all British dandelions reproduce asexually, every seedling is an exact clone of its’ mother,  This process is known as Apomixis.

Drawbacks mean that if a damaging mutation develops, it will not be diluted through reproductive gene mixing, and that particular plant will die out swiftly.

However, if a mutation is advantageous, it can dominate the population in no time.  Did you know that 16% of dandelions in the UK don’t produce pollen?  If you’re practising apomixis, pollen production is a costly and entirely unnecesary process.  Plants which don’t waste energy this way have a competitive edge.

Drawing a dandelion flower

Why botanists despair of dandelions

In the UK alone, there are 235 species or subspecies of dandelion, 150 of which are native.  Telling them apart is incredibly difficult as the differences between species is not constant.  Dandelions are incredibly plastic, adapting to changes to their environment.  One plant will have many phenotypes.  This explain why the task of separating dandelions to species level is so hard.

Dandelion plant

In Field handbook to British and Irish Dandelions (Richards 2021), there were only 51 dandelion experts listed worldwide, the earliest from 1798.  Compare this to botanists whose field of expertise is roses.  There are 39 Rose societies in the World Federation of Rose Societies.  The US branch has over 8,500 members while the National Rose Society in the UK had over 100,00 members at it’s peak.

As the BSBI, (source of much of the dandelion information in this blog) states, “dandelions are almost virgin territory for anyone wanting to research this plant group.”

Finding and recording Taraxacum luteum

When out with the Brecknockshire Botany county recorder recently, we found a wonderful species of dandelion, Taraxicum luteum.  Its’ main distinguishing feature was meant to be a bright, almost fluorescent yellow colour.  However, we found the pinkish bracts being pressed against the capitulum, and the absence of any dark lines on the back of the ray florets a far more useful indicator.  They also all seemed to have purplish stems, and central ribs of the leaves were flushed red too.

Taraxacum luteum from below

This species appears in the Flora of Brecknockshire, on the same site.  This comprehensive book (which I was lucky enough to collaborate on), was published last month. Luckily the book won’t have to be updated for this species of dandelion!

Health and Eating dandelions

Dandelions are natural diuretics, and can help fight cellulite and water retention.  In fact, the French name for dandelion is “Pissenlit”, which literally translates as pee in the bed.  This reflects their diuretic properties!  The roots can be made into a coffee substitute; the leaves can be eaten raw if young, and fried with butter when older.  Buds can be mixed into a pasta sauce with olive oil, garlic and salt and pepper.  Even the flowers can make decorative additions to salads and deserts.

Illustrating a dandelion in pencil

Conclusion

It’s easy to like dandelions.  Vilified by gardeners, disregarded as weeds, ignored by botanists.  They are beautiful, tenacious, adaptable, fascinating, edible, and instantly recognizable.  Harbingers of spring, and excellent for pollinators like the honey bee, there’s so much more to dandelions than meets the eye.  And a whole lot to love.

The post Dandelions: Why to love them appeared first on Lizzie Harper.

For descriptions of plant anatomy, look at my  the basics of botany blog, and on fruit types.  What’s in a name 1 and part 2 discuss how Latin names work and why they matter.  I have blogged on this family before, as it intrigues me, so feel free to look at my earlier blog.

Some of the other families I’ve examined include the Ranunulaceae (Buttercups), Caryophyllaceae (Campions), Rosaceae (Roses), Fabaceae (Peas), Brassicaceae (Cabbages), and Apiaceae   I hope to add a few more over the coming months.

Meadow thistle Cirsium dissectum

I am a botanical illustrator, but not a trained botanist.  So if you see a mistake, please let me know, thanks.

Wildflower families: Asteraceae

The daisy family has 1317 genus and over 21,000 species.  This makes it one of the most prolific plant families on earth. Flowers are small and either disc or ray form.  They cluster together in flowering heads called a capitulum, and have a distinctive appearance.  Dandelions, daisies, and thistles are Asteraceae.  Seeds are cypsela, a type of achene. As well as daisies, dandelions, and thistles, other Asteraceae include many garden flowers.  Chrysanthemum, Dahlia, Rudbeckia, Cosmos, Goldenrod and Gerbera are all in this family.

Chrysanthemum flower (Pom-pom variety)

Food crops are limited to Lettuce, Chicory, Salsify, Endive, and Globe artichoke.  The oil from Sunflower seeds is economically important, and the tubers of the Jerusalem artichoke are edible. There are lots of wildflowers in the Asteraceae, some (like Dandelion and its’ allies) can be incredibly difficult to identify to species level.  Knapweeds, Teasels, Chamomile, and Marigolds are Asteraceae.

African daisy Gerbera

Asteraceae overview

Plants in this family have varied leaves which are mostly alternate.  They don’t have stipules and frequently grow in basal rosettes, as well as on the stem.  A stipule is like a tiny leaf that grows in pairs at the base of a leaf stalk, next to the stem. Flowers have five fused petals, and  their stamens fuse to this tube. Flowers (florets) are disc or ray form.  The calyx is modified to a pappas. Seeds are a dry cypsela, achenes with one seed.

Milk thistle Silybum marianum with detail of disc floret and seed with calyx modified to a pappas

The name Asteraceae comes from the ancient Greek for star, via the Latin Aster.  It refers to the star-like flowering head.  This family used to be known as the Compositae, reflecting the composite nature of the flowering heads.

Asteraceae Leaves

The amount of variety in Asteraceae leaves is enormous, and they can not be reliably used to identify the family.  They can be simple or pinnate (divided).  Although most are alternate they can be whorled or opposite.

Creeping Thistle Cirsium arvense with alternate divided stem leaves and a basal rosette

However, most Asteraceae have a basal rosette, and most leaves are towards the bottom of the stem.  These are often larger and much more divided than higher stem leaves.  Look for a difference between base and stem leaves, this suggests a plant might be in the Daisy family.  A good example is the Sow-thistle.

Common blue Sow-thistle Cicerbita macrophylla

However, wildflowers from other species (like the Harebell Campanula rotunidfolia from the Campanulaceae) also have different basal and upper leaves.

Harebell Campanula rotundifolia showing different stem and basal leaves.  Harebell is NOT an Asteraceae

Asteraceae Flowers: Ray and Disc florets

All flowers are made of an assemblage of smaller florets, held in a capitulum.  They come in two forms, disc and ray florets. Disc florets are tubular, made of five petals fused into a tube, and have radial symmetry.  Ray florets are irregular, with one elongate petal (called a ligule) which tapers to a fused base around the flower parts.  Each yellow bit of a dandelion flower is a separate ray floret.  The florets attach to a receptacle, and the whole is the capitulum.

Echinacea diagram

Some species are a mix of ray and disc florets, like the Scabious, Cornflower, and the Daisy.  Ray florets on the outside, disc florets within.  The easiest plant to see this on is the enormous capitulum of the Sunflower, Helianthus annus,

Sunflower Helianthus annuus, Yellow ray florets on the outside, brown disc florets inside

Others are only disc florets.  Knapweed and Thistles fall into this category as does the Button-weed, Cotula.

Greater knapweed Centaurea scabiosa with disc floret and bract

Asteraceae which only have ray florets include all the Dandelions (Taraxacum agg), Hawkweeds (Hieracia), and Hawk’s-beard (Crepis).

Mouse-ear Hawkweed Pilosella officinarum

Asteraceae Flowers: Pappas and Involucral bracts

The sepals and calyx are reduced to a ring of hair-like pappus which become far more prominent when the seeds mature.

Carline Thistle Carlina vulgaris with seed, pappas around disc floret, and involucral bract detail

Often the capitulum is flanked with whorls of sepal-like leaves.  These are known as involucral bracts, or phyllaries. The number of whorls can help differentiate between species, as can their colour, and whether or not they have gland-bearing hairs.  This becomes really important when trying to identify the Dandelion-like species, known as Taxacarum agg, showing that there’s a whole aggregation of similar species.  A really helpful resource is the BSBI guide to Dandelions by A. J. Richards, but even experts accept that sorting these out to species level is difficult.

Mouse-ear Hawkweed Pilosella officinarum showing overlapping hairy involucral bracts

Capitulum may grow solitarily (like the Daisy) or in many-flowered clusters (like the Goldenrod Solidagao species)

Giant or Early Goldenrod Solidago gigantea

Each flower is bisexual and has five stamens with short filaments, fused to and alternating with the lobes of the corolla. Anthers are fused to filaments, and face inwards, forming a tube around the style.

Narrow-leaved Ragwort Senecio inequidens details

There are two carpels (the female reproductive organ of a flower, consisting of a style, an ovary, and a stigma.  Ovaries are inferior, growing below the flowering parts. For more on ovary positions look at my blog on the ovary.  The stigma, the top of the style and part that pollen lands on, is always forked and frequently curves back on itself.  The style grows within the tube made by the anthers, with the curved stigma emerging at the top.

Sunflower Helianthus annus Ray and disc floret, the latter clearly showing emergent curved stigma

Asteraceae Fruit

The fruit of the Asteraceae are cypsela.  Cypsela are a type of achene, a single-seeded dry fruit.  Cypsela come in various shapes, and often are crowned with the pappas, hairs.  Pappas frequently lengthen after fertilization to form the familiar dandelion clocks and fluffy seeds we see being disbursed by the wind.

Giant or Early Goldenrod Solidago gigantea seed

There’s plenty of variation here, too.  Some cypsela have beaks, a stem holding the pappas (like a Dandelion).  Others simply have a ring of hairs attached to the seed.  The pappas hairs can be simple or branched.  Some species like the Pot marigold, Calendula officianlis have no pappas, but are an amazing curved and lumpy shape.

Dandelion Taxacum officinale seeds

Asteraceae: Other species

As well as the species listed, Yarrow, Tarragon, Arnica, Burdock, Groundsel, Ragwort and Ragweed, and Echinaceae are all members of the Daisy family.

Ragwort Senecio jacobaea

Conclusion

Sorting out the Asteraceae, with its ray and disc florets and cypsela, seems daunting at first.  However, it’s a magnificent family, and the tiny florets are well worth a closer look with a hand lens.  I’ll be doing more of these wildflower family blogs over the coming months.  References include my FSC botany course delivered by Iain Powell, the Common Families of Flowering Plants by Michael Hickey & Clive King, and the excellent Naturespot website.

Marsh hawksbeard Crepis paludosa

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Overview of Canadian Goldenrod Solidago canadensis and Early Goldenrod Solidago gigantea

The focus of the illustration is the Canadian goldenrod.

Most Goldenrods are native to the Americas.  However, there’s one species native to Europe (Woundwort Solidago virgaurea).

Both Canadian and Early Goldenrod Solidago gigantea grow wild in Scandanavia.  Garden escapes were noted as early as 1910.  Although it’s an invasive, and can be a nuisance, Goldenrod does bring benefits.  It’s extremely good for pollinators, and attracts lots of butterflies.  As it flowers late in the year, it provides a welcome food supply for insects about to overwinter.  (To make your garden wildlife friendly, check out the Save the Bees guest blog.)

Goldenrod plants grows on waste ground.  Sometimes they form dense clumps along railway tracks and roads.

Canadian goldenrod flowers August to October.  However, Early goldenrod blooms from July.

Goldenrod is a member of the daisy or Compositae family.  As with other members of this large and successful group, its flowers are made of disc and ray florets.  For more on this, please check out my blog.

Canadian goldenrod

The Canadian goldenrod plant is tall, 30 – 150 cm.  Densely leafy, it’s covered in downy hairs which are more obvious toward the top of the plant.  Giant or Early goldenrod is glabrous.  It’s a larger plant, up to 250 cm high.  Often, its stems are blueish towards the base.

The plant reproduces by means of far-reaching rhizomes, and with seeds.  These have fluffy pappas which catch the wind and spread the seed widely.

Leaves

Canadian goldenrod leaves are alternate and toothed.  About 2/3 of the way down the leaf edge the teeth give over to leave a smooth margin toward the base.  As with the rest of the plant, they’re hairy.

Early goldenrod has teeth which carry round the entire margin of the leaf.  Any hairs follow the lines of the veins.

Early goldenrod and Canadian goldenrod leaf comparison

Canadian goldenrod leaves have three veins; while the Early goldenrod sports five.

Stems

The stem of Canadian goldenrod is covered in downy hairs.  It is often flushed red.  Stems of the Early goldenrod are hairless, and may be flushed red or a more intense purple.

Early goldenrod stem compared to Canadian goldenrod stem

Flowering spike

The flowering spike is similar in both species.  It carries lots of golden flowers, and tends to curve a little.

Canadian goldenrod with comparative notes on Early goldenrod

Individual flowers

Each individual flower is composed of ray florets around the outside edge, and disc florets within.  Both have 5 yellow stamen.  There are some noticeable differences between these golden blooms.

The Canadian goldenrod is 5 – 6 mm across and has 10 – 17 short ray florets per flower.  Tips of each are blunt, and rounded.  In shape, the capitulum is domed.  Flowers are carried in wide, pyramid-like panicles.

With the Early goldenrod, there are fewer ray florets per flower, 7 – 12 of them.  Each flower is a smaller 2 – 3 mm.  Ligules of the ray florets are significantly longer, with more pointed tips.  Another differnce is the capitulum, which are are more pyramidal than in Canadian goldenrod.  The flowering branches tend to be straighter and held more erect.  Branches may be slightly hairy towards their top.

Early goldenrod flowers compared to Canadian goldenrod flowers

Seeds

These are similar in both species, but the Early goldenrod has longer pappas.  Canadian goldenrod seeds have a slightly downy tip.

Currently in Sweden and Finland the cold weather comes before the Early goldenrod sets seed.  As global warming leads to longer summers this plant could become an increasingly problematic invasive in Scandinavia.

Early goldenrod cypsela vs that of the Canadian goldenrod

Resources

Naturespot has helpful and concise information on the Canadian goldenrod and on the Early goldenrod.  Yet again, Naturegate has great pages for both Canadian and Giant goldenrod.

This original sketchbook illustration is available for sale along with many other original illustrations.  Why not have a browse at Original Illustrations for sale?

The post Comparing Goldenrod Species appeared first on Lizzie Harper.

The terminology of flower parts can be complex, so below is a labelled diagram, adapted from an illustration I did for The New Amateur Naturalist by Nick Baker.

(For a clear and more detailed overview of general flower anatomy and funtion, have a look at the RHS slideshow.)

Asteraceae or Daisy family overview

The daisy family has the most species within it, after the grasses.  Lots of familiar flowers like thistles, daisies, ragwort, and dandelions fall into this group.  The amazing thing about these flowers is that each individual flower head, each daisy or dandelion, is in fact, a cluster of many tiny flowers (known as florets).  These florets come in two forms; ray florets and disc florets.  Both floret types are formed of five joined petals which either form a tube (disc floret), or a short tube with one lengthened lobe or strap which extends outwards (ray florets).  The assemblage of florets are called a flower head, or capitula.

Ray florets

Ray florets tend to be larger than disc florets and often form an outer “ring” of a composite flower (think of the white “petals” of a daisy).  The disc florets can be tiny, and form what we often think of as the centre of a composite flower (the brown area of a sunflower, the yellow centre of a daisy).  If you have a dissecting microscope, or even a 10x hand lens you can see these two types clearly; just tease a daisy apart, preferably over a black background.

Generally, surrounding the florets is a ring of small leaf-like bracts which vary in size and shape according to species.

Now, not all members of the daisy family have both types of floret.  Some only have disc florets.  Some only have ray florets.  Some do, indeed, carry both types.  Below are some examples of all three types.

Composite flowers bearing only disc florets

Thistles and similar flowers are Asteraceae representatives which only bear disc florets, as is tansy and cornflower.  First, let’s look at a common knapweed.

This flower head is borne at the tip of a stem, and made of identical purplish disc florets.  The base of the flower head is overlapping bracts; and the brownish hairy appearance is due to the edges of these bracts looking feathery or fringed.

Don’t be fooled by the larger, star-like florets you may see at the outer edge of some knapweed flower heads.  these are also disc florets, but are sterile and enlarged; their star-shape is due to deep lobing.

Knapweed flowers progress form male to female with time, so younger (male) flowers cross pollinate older (female) ones (thanks to insects).

Butterbur is a wonderful plant; it’s leaves only appear once the flowers have died.  Female and male flowers (all are disc florets) appear together with the females on longer stalks and developing into plumed seeds.

This butterbur illustration I did is from Collins’ Flower Guide (butterbur species at bottom and top left); below is a sketchbook study.

Composite flowers bearing only ray florets

Species carrying only ray florets include the dandelion and its allies, chicory, salsify, and lettuces.  Let’s look at the dandelion.

The 200 or so ray florets making up the head of a dandelion are hermaphrodite; and close when it’s dark, dull weather, or (devastatingly for the illustrator) soon after being picked.  The bracts help distinguish dandelion from similar species; there’s an outer ring which spread and an inner set which remain erect.  Dandelions carry each seed at the base of a parachute of hairs on a long stem; before the wind disperses them these form the distinctive dandelion globe-like “clock”.

Another species bearing only ray florets is chicory, which is a joy to paint as it’s such a glorious blue.

Composite flowers bearing disc and ray florets

These plants carry both floret types, with rays round the edge of a group of disc florets.  Lots of the Asteraceae fall into this group; along with asters and sunflower, there’s also yarrow, rudbeckia, fleabane, ragwort, burdock, arnica, marigolds…

The Ox-eye daisy is made of white female ray florets surrounding yellow hermaphrodite disc florets.

The sketchbook study shows the arrangement of the disc florets; it’s worth remembering that they are formed by two spirals winding in opposite directions.  This helps plot the position of each disc floret.

Also remember that the disc florets in the very centre of a flower head will be the last to mature, flower, and subsequently form seeds.  This is particularly helpful with the sunflower.

The sunflower is a lovely specimen as everything about it can be so large, and so easy to dissect out and examine.  The colours of the disc florets are particularly interesting, with age they can become dark brown or even a deep purple.

I hope this rather botany-heavy blog has helped show the amazing variety, and wonder of the Asteraceae or daisy family.  The more you think about the scale of these tiny florets all forming one flowering head, or examine the details of each ray floret, or the pattern formed by hundreds of tiny disc florets; the more wonderful they seem, and the more I want to investigate and draw them.  Many thanks to members of the Botanical Art for Beginners group for suggesting this as a blog topic; click on the link for more information on the Asteraceae family.

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