Close-up view of a flowering Echeveria.

Members of the genus Echeveria are described as succulents. These plants can grow in very dry environments, because they have the ability to store water in one of three locations – the leaves, stems or roots. The best known succulents are probably the cacti, which store water in their swollen stems. Echeveria’s, by contrast, store their water in their thick, engorged leaves. These leaves are usually arranged in a striking rosette. The best known Echeverias, sometimes referred to as “Hen and Chicks”, have many offsets which produce dense packings of rosettes. (Since other genera are also referred to by the same common name, the term “Hen and Chicks” is probably best avoided.) Echeveria refers to a 19^th century Mexican botanical illustrator Atanasio Echeverria.

Most Echeverias are native to Mexico and Northwestern South America. They are however, available worldwide from tropical plant distributers. To get some idea of the large number of species available, take a look at the second internet site listed under ‘Further Information’ at the end of the article.

The image below shows the Echeveria species photographed for this discussion. It was obtained during the winter period from my local horticultural centre. A single, tall (20 cm) stem grows out of the rosette of thick, pointed leaves. At the top of the stem, six flowers are in varying stages of development.

The leaves that form the base rosette are green, with their very tips being a pale yellow colour.

The flowering stem has a reddish colouration, and several bract-like structures are present along its length.

Notice the unusual cross-section of the leaves.

The plant’s upper stem is curved, which results in some of the buds and flowers facing down. Flowers bloom from bottom to top on the stem. The image shows the development from bud to mature flower.

Here is an example of an early stage bud. Notice the ring of thick, pointed, green bracts that surround the developing petals. (The image also shows an unfortunate characteristic of this plant that is a curse to macro-photographers. All of the plant’s surfaces are covered with a waxy white coating that becomes scuffed as the stem grows up through the rosette leaves. These scuff-marks can be seen clearly at the bases of the bracts.)

This same white coating can be seen on the main stem, and attached cup-like bract in the image below.

Notice in the images that follow, the colour transformation of a bud as it increases in size. Green to begin with, the colour changes to a bright orange-red, and finally fades to a paler orange-yellow. At all stages, the tips of the flower’s petals are tinged with green.

Here are two images showing the flower as the petals begin to open out to reveal the reproductive organs.

Photomicrographs showing sections of one of the flower’s petals reveal the strange, coloured particulate matter that is present on the surface of the cells near a strongly pigmented area. The image on the right shows a less pigmented area which has none of these particles.

It is not only in the plant’s leaves that water is stored. If a section of petal is held flat between two microscope slides, a slippery liquid escapes from the cells. Bubbles formed within this liquid can be seen in both images.

The flowers in the images below have opened to their maximum extent. Numerous pollen encrusted, yellow anthers, (male pollen producing organs), are held aloft by paler filaments. At the flower’s centre, five pale green stigmas, (female pollen accepting organs), are so close to one another, that several are touching.

Higher magnification reveals more detail. Here again, several of the stigmas seem fused together.

By removing several petals and bracts, one can get a better idea of the arrangement of the reproductive structures. Notice that the pale green styles that support the stigmas are connected to swollen, white ovaries (seed producing organs). (Note the droplets of watery liquid that are exuded by the wounds left when the petals are removed.)

The pollen encrusted anthers are remarkably similar to those of most other plants.

The tip of the stigma is coated with a very sticky liquid that helps to retain pollen grains. Missing are the tiny hair-like protuberances that are present on the upper surfaces of most other plants’ stigmas.

It is said that there are at least 10 000 unique species that are described as succulents. Why not take a close-up look at any that you come upon?

Photographic Equipment

All of the macro-photographs were taken with an eight megapixel Canon 20D DSLR equipped with a Canon EF 100 mm f 2.8 Macro lens which focuses to 1:1. A Canon 250D achromatic close-up lens was used to obtain higher magnifications in several images.

The photomicrographs were taken with a Leitz SM-Pol microscope (using a dark ground condenser), and the Coolpix 4500.

Further Information

Echeveria
http://www.desert-tropicals.com/Plants/Crassulaceae/Echeveria.html

Echeveria
http://www.lapshin.org/succulent/eche-l.htm

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.

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