rigens 'Gazoo Red'
by Brian Johnston (Canada)
This extremely photogenic member of the
Asteraceae family is distinctive because of its glossy green
uniquely colourful blooms. In particular, it has an
band at the base of its ray floret petals, and the tips of these
petals transition from orangy red to pink.
Like other members of the
family, the blooms are actually flower-heads composed of disk
at the centre, and ray florets around the outer perimeter.
in the article, we will take a detailed look at the flower’s
The Gazania flower was first
described in the literature by the German botanist Joseph
Gaertner. It was subsequently named in honour of Theodore
who is remembered as producing the first Latin translation of
botanical works of Theophrastus.
The flowers of ‘Gazoo Red’,
many other members of this genus, close up at night and on
cloudy days. It is therefore recommended that it be
planted in a
location that receives full sun.
Side views of a flower-head
the whorls of overlapping sepals that together form the
Notice that the sepals in the outermost whorls bend back, away
showy ray florets.
From the front, the
outer ray floret petals appear to have many longitudinal ridges.
Viewed from the back, these
petals appear to have a colouration which tends more towards the
Closer views reveal the
flower-head’s calyx (left), and the pattern of reddish
lines on the undersides of ray petals (right).
Higher magnification shows the
colourless spikes that grow from a sepal’s edge.
One would expect that all of
flowers on a plant would have identical colour patterns.
not the case here. Notice that although the inner beige
the same, this flower has much brighter, uniformly red, ray
If one of these petals is
under the microscope, its cellular structure is revealed.
shape of an individual cell is remarkably rectangular.
It is amazing that such
spectacularly colourful flower-heads can develop from such a
Hiding beneath the protective
whorls of sepals are the developing ray, and disk buds which
cream or yellow colour.
In the image below, you can
dome-shaped, brilliantly white receptacle from which the buds
Note the particularly
design of the connection of the stalk to the receptacle.
that the pale green stalk is covered with a white membrane which
appears to be flaking off in some areas.
It takes about 48 hours for a
bud-stage flower-head to go from the stage seen on the left to
seen on the right below.
Still another two days is
for the flower-head to begin to bloom.
Notice that the disk
flowers haven't begun to bloom, but the outer ray florets have
most of their final length. However, they are still curved
tube-like shapes, and must still uncurl.
The uncurling process has
these images, but the ray florets are still positioned to form a
When the flower-head has
opened, its ray florets and central disk are almost
to the stalk. Note the tight packing of the sepals, and
floret petals, in the bud shown at right.
It’s time to look more closely
Gazania’s reproductive structures. In the flower seen
ray flowers are in full bloom, but only an outer ring of disk
have opened. The reddish-brown central disk of the
flower-head is composed of unopened disk flower buds.
If we look more closely at the
blooming yellow disk flowers, it is evident that each has 5
petals, with a rod-like structure projecting from its
Bud-stage disk flowers have a rounded, reddish-brown tip and
These rod-like projections,
are the flowers’ pistils, can be seen more clearly in another,
colourful flower. One might surmise, from the liberal
pollen grains, that these structures were anthers, but one would
incorrect. In the Asteraceae family, the anthers are
within the flower’s corolla tube, and as the long stigma, and
supporting style extend up through the corolla tube, they brush
the anthers, and pick up a coating of pollen. In order to
discourage self-pollination, the two active surfaces of the
stigma are tightly sandwiched together during this
later do the two lobes of the stigma separate, and become
pollen. We will see this process later in the article.
Removing some of the sepals
florets from a flower-head makes it easier to see the white
receptacle from which the florets grow.
The images that follow show
tightly packed disk flowers with their five petals and rod-like,
Closer views reveal that the
of one of the disk-floret stigmas have separated forming the
forked, bi-lobed structure.
As mentioned earlier, disk
buds have rounded reddish-brown tips, and yellow and cream
The first image below shows
stigma that has its lobes separated. This floret is at the
outer edge of the central disk. The next floret out would
the ray variety.
These two images, taken of a
brilliantly coloured flower-head, show pistils with unseparated
lobes. If however, you look very carefully at the second
you can see a stigma where the process of separation has just
If one of the pistils seen in
previous image is examined under the microscope, the red style
seen exiting through a ring of yellowish-beige anthers.
anthers do not have the same appearance as those of other plant
families. Here they are elongated with pointed tips, and
pollen generating tissues are on their undersides, facing the
style. Pollen grains can be seen clinging to these
the base of the style, in the images.
Closer views of the top of an
anther reveal its cellular structure.
Here, the transition zone
the top of the style, and the bottom of the stigma, can be
Notice the stubby, hair-like protuberances around the bulge at
Higher up the structure, the
lobes of the stigma have separated in most flowers. Notice
since the two receptive surfaces were in intimate contact during
trip up past the anthers, there are relatively few pollen grains
Photomicrographs showing the
bi-lobed stigmas can be seen below. Note the detail on the
surfaces of the perfectly spherical pollen grains.
Other views showing sections
these anthers and supporting styles, follow.
No, your eyes are not
you! The stigma shown in the two images that follow has
lobes – double the usual number! Obviously this is
the fact that there are no hard and fast rules in botany!
Gazania leaves are a bright,
green, and can have a variety of shapes depending on where they
located. There is one prominent vein on each leaflet.
Higher magnification reveals
interesting details on a leaf’s upper surface.
The undersides of leaflets, on
other hand, are a different story. A darker green ridge
around the perimeter of each leaflet, and a wide vein runs its
length. Extremely fine, almost downy hairs cover its
longer, sturdier hairs sparsely cover the stalk.
Some parts of Gazania plants
poisonous, however ingestion usually produces only mild
gastrointestinal distress. It is not recommended to allow
The low magnification, (to
macro-photographs were taken using a 13 megapixel Canon 5D full
DSLR, using a Canon EF 180 mm 1:3.5 L Macro lens.
A 10 megapixel Canon 40D DSLR,
equipped with a specialized high magnification (1x to 5x) Canon
lens, the MP-E 65 mm 1:2.8, was used to take the remainder of
The photomicrographs were
using a Leitz SM-Pol microscope (using a dark ground condenser),
the Coolpix 4500.
A Flower Garden of
A complete graphical index of
of my flower articles can be found here.
The Colourful World
A complete graphical index of
of my crystal articles can be found here.
Microscopy UK or their contributors.
Published in the
May 2013 edition of Micscape.
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