A Close-up View of the Wildflower
"Yellow Goat's-Beard"

(Tragopogon dubius)

by Brian Johnston   (Canada)

A casual glance at this bright yellow wildflower might leave the observer with the impression that it is a dandelion on steroids!  It is in fact a member of the same family, (aster), but there are many differences that contribute to Yellow Goat’s-Beard’s uniqueness.

The most obvious difference is size.  Goat’s-Beard can grow up to a metre in height, and the single composite flower-head containing both ray and disk flowers can have a diameter up to seven centimetres.  This large flower-head opens and twists slightly towards the sun each morning.  In the early afternoon, the flower-head closes again.  The English poet, dramatist and essayist Abraham Cowley (1618 - 1667) wrote the following about the Goat’s-Beard plant.

The goat's beard, which each morn abroad doth peep
But shuts its flowers at noon and goes to sleep.

The propensity for early closing resulted in old country names of “Noon-flower” and “Jack-go-to-bed-at-noon” being given to the plant.  The genus name Tragopogon comes from the Greek words tragos, meaning ‘goat’, and pogon meaning ‘beard’.  This is in reference to the seed-head of the plant (which will be shown later).  The species name dubius can be translated as ‘doubtful’, and may refer to the fact that, due to hybridization with other similar species, identification may be uncertain.

One of the most important characteristics of Yellow Goat’s-Beard is the ring of sharply pointed modified leaves called bracts which are arranged in a radial pattern beneath the flower-head.  In this species these bracts must be longer than the petals.  The first photograph in the article, and the two images below show these bracts.  Note that the number of bracts is variable, but most plants have about ten.

A swollen growth at the base of the flower-head is another characteristic of Yellow Goat’s-Beard.  It can be seen in the right-hand image above.

The first flowers to bloom in the composite head are the outer ray flowers to which the yellow petals, called ligules, belong.  The pale green, yellow tipped columns at the centre of the head are immature stamens.

The three images below show side views of the outer ray flowers.  The dark, almost black columns are actually tubes formed by fused anthers (the male pollen producing structures).  Growing up through each of these tubes is the style, which supports a two-lobed stigma (the female pollen accepting structure).  It has been my experience that the beautifully curled lobes of the stigma exist for a very short time, and they soon straighten out to a straggly ribbon form.  All three images show that the stigma’s surface is coated with tiny pollen grains.

The unkempt appearance of the stigma lobes after a period of time can be seen in the following image.

A closer look reveals more detail.  In particular, notice that each of the anther columns forming the central structure in the image, is divided at its tip by fine black lines, into five sections.  These are the five anthers which are fused to form a particular column.  Given time, the stigma and style will grow up through this tube and beyond it.

As the flower-head matures, the central columns straighten slightly to reveal a dark centre.  Compare the two images below with the one above, in which no dark centre is visible.

Two further images of a flower-head are shown below.  Note the swollen base in the first image.

Under the microscope, the details of a fused column of anthers can be seen.  Note that three of the five anthers are visible in the photomicrograph, each with a triangular top.  The yellow column protruding from the end is the style.

The highly magnified central longitudinal ridge of one of the anthers is shown below.

In the following photomicrograph, the bi-lobed stigma has just pushed out of the anther tube.  As time passes, it will grow out still farther, revealing the style that supports it.

A much higher magnification image of the exit point of the style is shown below.  Note the hair-like protuberances on the style’s surface that tend to capture any pollen that come into contact with them.

Two further images reveal the many pollen grains which have become stuck to the surface of stigma and style.

The surface of a pollen grain appears to be pock-marked by many tiny depressions.

A Second Species  (Meadow Goat’s-Beard ?)

The flower-head in the two images below looks remarkably like Yellow Goat’s-Beard, but the pointed green bracts are shorter than those of that species.  This is ‘probably’ Meadow Goat’s-Beard,  Tragopogon pratensis.  I say probably, because although pratensis does have shorter bracts, it is not supposed to have the swelling beneath the flower-head - and this one clearly does.  Welcome to the nightmare of identifying Tragopogon species!  One possibility is that all of the many Tragopogon species tend to form hybrids when unknowing insects carry the pollen of one plant to another of a different species.  The resulting hybrids have a mixture of the properties of both plants.  This may bring joy to a plant taxonomist’s heart, but not to mine!

The swelling at the base of a flower-head is particularly noticeable while still in bud form.

The three photographs below demonstrate how similar the Meadow Goat’s-Beard flower-head is to that of the Yellow Goat’s-Beard’s.

Back to Yellow Goat’s-Beard

Once the flower-head has finished blooming, a remarkable thing happens.  The bracts close up around the fertilized flowers, completely hiding them from view.

If the bracts are cut away, it is possible to see the developing seeds and pappae, composed of the hairs that will eventually form the dandelion-like parachute.  Note, in the image on the right, that the spiked seeds are beige in colour.  The white columns beyond the narrow green rings are composed of the fine white threads which will eventually form the parachute.

The higher magnification photographs which follow reveal details of the developing seeds and the green rings which are the point of attachment of the pappae.

As can be seen in the two images below, the seeds, called achenes are covered in spikes which form on the many longitudinal ridges.

It is interesting to note that if several of the outer achenes are removed, those visible in the inner core have greatly reduced spikes on their surfaces.

Once the seeds have sufficiently matured, the bracts re-open and the pappae on their long stalks begin to dry out and open into parachutes.

When this process is complete, the startlingly large (up to 10 centimetre!) globe-shaped plumed head is revealed.  These balls of parachutes completely dwarf those of the largest dandelion.

A gust of wind is all that is needed to dislodge seeds from the white pad to which they are attached.  (For this photograph, I acted the part of the wind in order to remove the front-most achenes.)

While searching in the field with my trusty magnifier for a photogenic specimen, I noticed the seed-head below.  Several of the central seeds and pappae have failed to grow properly and have formed an interesting and unique basket-shaped cage.  In the last image, note the strange shape of the depressions in the pad to which the seeds are attached.

The parachute of a Goat’s-Beard seed is almost flat and the surface is perpendicular to the column that attaches it to the seed.  Strong (beige) radial ‘arms’ attached to the central column hold fine (white) fibers that completely fill the space between the arms.

Under a higher magnification, it can be seen that these fibers form a tangled web between each pair of radial ‘arms’.

When I first became interested in the macro-photography of wildflowers two summers ago, Yellow Goat’s-Beard seed heads were abundant.  Although it was only August, I could find no flowers.  (To be truthful, I did find several very misshapen examples that were too ugly to photograph.)  With less than perfect patience, I had to wait until this past summer to obtain images of flower-heads.  Strangely, this summer, which was much cooler and wetter than the previous one, proved to be ideal for Yellow Goat’s-Beard.  Flowers bloomed right up to the middle of September!  It was worth the wait.  This plant is one of my top ten favourite wildflowers.

Photographic Equipment

The photographs in the article were taken with an eight megapixel Sony CyberShot DSC-F 828 equipped with achromatic close-up lenses (Nikon 5T, 6T, Sony VCL-M3358, and shorter focal length achromat) used singly or in combination. The lenses screw into the 58 mm filter threads of the camera lens.  (These produce a magnification of from 0.5X to 10X for a 4x6 inch image.)  Still higher magnifications were obtained by using a macro coupler (which has two male threads) to attach a reversed 50 mm focal length f 1.4 Olympus SLR lens to the F 828.  (The magnification here is about 14X for a 4x6 inch image.) The photomicrographs were taken with a Leitz SM-Pol microscope (using a dark ground condenser), and the Coolpix 4500.  

Note:  Since the photographs in this article were obtained over a period of two years, my Sony DSC-F 717 and Nikon 4500 were used to take the earlier photographs.  They can be distinguished by the fact that the gray frames around them are of slightly greater width.


The following references have been found to be valuable in the identification of wildflowers, and they are also a good source of information about them.

A Flower Garden of Macroscopic Delights

A complete graphical index of all of my flower articles can be found here.

The Colourful World of Chemical Crystals

A complete graphical index of all of my crystal articles can be found here.

 All comments to the author Brian Johnston are welcomed.

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