A Close-up View of Two

"Freesia" Flower Hybrids

(Freesia hybrida Hort.)

by Brian Johnston   (Canada)

This attractive small flower is native to South Africa and Australia where it often grows in such numbers in woodlands and disturbed areas that it is to referred to as an “infestation”.  In Southern Ontario, where I live, the plant is sometimes available as a cut-flower for use in floral arrangements.  For the purposes of this article, I obtained two hybrid varieties that had been grown in the Netherlands and transported by air to Toronto for a nearby exotic flower retailer.  This is a perfect example of how small the world has become, and how fortunate we are to have such floral abundance at our fingertips!

Freesia grows from a corm, a solid bulb like that of the gladiola plant.  The genus name Freesia was named after the German physician F.T.H. Freese who died in 1876.  The stem usually branches only once and therefore has a characteristic Y shape.

The two images that follow show that the buds and flowers grow in a helicoid cyme, an arrangement in which they are attached to the stem in a spiral fashion, but nevertheless always face in a single direction.

A higher magnification reveals several details.  The final flower colour is shown only by the tip of the bud, the remainder being yellow-green.  The bud grows up through dark green spathes which are conspicuous bracts (modified leafs) that partially surround it.

Once a flower blooms, a long white pistil that branches at the tip is visible at its center.  The right-hand image shows a better view of the two spathes that enclose each bud’s base.

Like many other plants, the buds of freesia are extremely photogenic.  For the purpose of the next section, take particular note of the top of the spathe in the image at right.  Note that it is not green, but light brown in colour.

If the brown, topmost edge of the spathe is observed under the microscope, and illuminated by a dark-ground condenser, it has a rope-like appearance.

Just beneath the edge, in an area that looks almost white and translucent, individual cells are resolved.

Closer to the opaque green section of the spathe, the cells are indeed green, and brown veins are visible.

A lower magnification shows these branching veins.

Look closely at the bottom of the vein just to the right of center in the image that follows.  The vein appears to be composed of long cells that have a multitude of closely spaced rings along their length.

After a flower has finished blooming, it shrivels up and drops off.  The enclosing spathe however, remains attached to the stem and partially dries out appearing like a papery brown membrane.  When this membrane is examined, all kinds of strangely shaped sections can be seen.  The triangular one below is particularly noteworthy.

The three photomicrographs that follow show the cells that make up the base of the spathe.  (The brown coloration is due to its age.)

Once a funnel-shaped flower blooms it is evident that there are two layers of petals.  Each layer is composed of three petals.  Typical flowers are 3 to 4 centimetres in diameter.

The two images below show that some of the petals curve inwards towards the center of the flower.

When a petal is examined under the microscope, the red striations that were observed in earlier images can be seen in greater detail.  The cells making up the petal’s surface are roughly spherical in shape.

A still higher magnification reveals that the cells have wrinkled rather than smooth surfaces.

As you have seen, the first freesia hybrid to be photographed has an orange-red colour.  The second hybrid is bright yellow.  The bud arrangement is the same as before, a helicoid cyme.  Many of the buds and flowers have their spathes discoloured by brown spots.

As the buds grow larger, the spathes are forced to open more, much like jaws.

Notice the strange shape of very early buds in the lower half of the two images that follow.

Occasionally the bottom of the flower’s funnel is wrinkled or dimpled as is the one on the left of the image below.

Most blooms are remarkably perfect in form.

The three photographs that follow show different views of the same section of the cyme.

Since this second hybrid has more rings of closely packed petals, it is more difficult to see the pistil.  I therefore have removed all of the petals from the flower in order to obtain the view seen on the right.

A closer view, without the distractions of the rest of the plant, shows the main features of the female reproductive parts of the flower. There are three reproductive ‘parts’ called carpels that are fused together (connate), part way down the structure.  Each of the three stigma tips (the pollen accepting organ) has a distinctive heart shape that is split open at the base. Since these stigmas look vaguely like petals they are referred to as “petaloid”.

A photomicrograph of the stalk supporting the stigmas shows that it has many columnar sections.

The stigma possesses many fine ‘hairs’ or projections that help catch and hold pollen grains.

These projections are connected to the fan-shaped stigmas.

Higher magnification reveals that the projections come in different shapes and sizes.

One of the stigmas has this single spiked projection growing from its base.

Freesias are said to be synoecious, since they have both male and female flowers in the same helicoid cyme.  My two hybrids seem to be ‘freaks of nature’ since I could not find a single male flower!  In fact, I was unable after much searching, to find any pollen grains on the petals or stigmas of the plant.  (If any reader can explain this mystery, I would appreciate hearing from you.)

The showy flowers of the Iridaceae family to which freesia belongs, are widely cultivated.  (The crocus, gladiola and iris are also members of the same family.)  By the mid 18th century, freesia was cultivated in Europe, but it wasn’t until the late 19th century that selective hybridization was attempted.  Today, freesia is grown in very large numbers for the worldwide florist trade.

Photographic Equipment

The photographs in the article were taken with an eight megapixel Canon 20D DSLR and Canon EF 100 mm f 2.8 Macro lens. A Canon 250D achromatic close-up lens was attached to the EF 100mm lens in order to obtain a higher magnification for a few images. The 250D screws into the 58 mm filter thread of the camera lens. The photomicrographs were taken with a Leitz SM-Pol microscope (using a dark-ground condenser), and a Nikon Coolpix 4500 camera.  

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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Published in the January 2009 edition of Micscape.
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