A Close-up View of the Geraldton Waxflower

The Geraldton Waxflower is often used by florists in cut-flower arrangements. Although it is widely available, the plant is native to western Australia where it grows as an evergreen shrub in gardens, and along roadsides. It is considered to be one of Australia’s most famous wildflowers, and this popularity has spurred the development of plants with many different colourations (white, yellow, pink, purple, lilac, and bicolours). Surprisingly, it is in Israel that much of the physiological and horticultural research on this species has been done. Most Waxflower plant material in Europe originates from that country. In North America, plant material usually originates in California or Mexico, although Peru is also a producer. Australia itself sells to most of the world.

The genus name Chamelaucium is probably from the Greek - chamia meaning “dwarf” and leucos meaning “white”. Uncinatum means “hooked”, and refers to the tips of the needle-like leaves. The Waxflower is a member of the Myrtle (Myrtaceae) family.

The first image in the article, and the one below, show the main characteristics of the plant. The 10 to 15 millimetre diameter flowers in my sample were pale yellow, tinged with pink. Many bright green needle-like leaves about 25 millimetres long contrast with the woody brown stems.

A close-up of a portion of the main stem reveals this rather strange looking branching point, with two larger diameter green flower stems, and two narrower diameter yellow-green leaf stems.

Each of the tiny flowers contains five waxy petals, and has a dark pinkish-purple centre.

The following images show the before and after appearance of a bud about to bloom. Notice that the sepals (modified leaves) are fused in this species to form a scalloped, cone-shaped base (or calyx) for the flower. Notice the interesting depressions and colouration of the calyx in the second image.

The mature flower contains one central pistil, composed of the stigma and supporting style, (the female, pollen accepting organ), and a variable number of stamens, (about 15), composed of anthers and their supporting filaments, (the male, pollen producing organs).

Three of a flower’s petals have been removed to show the distinctive narrowing of the style from bottom to top.

Notice the ring of reddish anthers in the following image. Also notice the circular shape of each petal, and the narrow connection of the petal to the circular “floor”.

An interesting variation in structure makes the stigma of a Waxflower a real “pollen magnet”. Tiny sticky hair-like filaments extend out into space from the central stigma core.

A side view of a stigma under the microscope can be seen below. Most of the sticky hairs shown in the previous two images have been removed by the manipulation necessary to get the specimen into position on the slide, but several are still visible. The yellow material seems to be a semi-solid, sticky glue-like substance quite different from that of the stigma itself, (the red elliptical structure).

Higher magnification of one of the hairs reveals that it is not of constant diameter.

The cellular structure of the style is shown below.

A photomicrograph of an anther and filament follows. Note the tiny rice-shaped pollen grains sticking to the anther’s surface in the right hand image.

I placed a small quantity of the sticky material coating the surface of the stigma onto a slide, and used phase-contrast illumination to study the sample. Unfortunately, I have been unable to find out what the unusual flat-tipped triangles are.

The transportation of Waxflower cut-flowers to distant locations around the world is difficult. One problem is that the buds and flowers tend to fall from the main stem, (a process called abscission), during the process. Two solutions to the problem have been found. One is to hydrate the plants in refrigerated water. The other involves dipping the cut flowering shoots in a chemical called auxin, a plant hormone. The chemical name for this substance is indole-3-acetic acid (IAA). Auxin’s structural formula and molecular shape are shown below. (Forgive me, but my chemistry teaching background just asserts itself every once in awhile!) Both images were produced by HyperChem Pro.

Although most of my wildflower articles concern native Ontario plants, I find it rewarding during the winter to visit a florist or horticultural centre to obtain specimens from other parts of the world. The botanical diversity of our planet is truly amazing!

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.

Further Information

More information concerning the Geraldton Waxflower can be obtained from the following sites:

Geraldton wax and relatives :

http://www.rirdc.gov.au/pub/handbook/gwax.html

Floricultural use of native (Australian) plants :

http://www.parliament.vic.gov.au/enrc/inquiries/old/enrc/unff/report/util3-03.htm

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