Close-up view of a flowering Echeveria.
View of a Flowering
by Brian Johnston (Canada)
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 19th
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 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
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
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
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?
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.
A Flower Garden of
A complete graphical index of all
of my flower articles can be found here.
The Colourful World of
A complete graphical index of all
of my crystal articles can be found here.
Microscopy UK or their contributors.
Published in the March
2011 edition of Micscape.
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