Close-up View of the
caerulea 'Origami Red & White'
by Brian Johnston (Canada)
The elegantly shaped columbine with its
long, distinctive spurs, exists as both wildflower and garden
flower. Wildflower columbines (approximately seventy species),
grow throughout the Northern Hemisphere in climates ranging from warm
temperate, to arctic alpine. Their structure is unusual; other
spur-bearing flowers such as impatiens, violets and larkspurs possess
only one spur per flower, while the columbine has five!
This feature, coupled with the flowers’ attractive colouring and
foliage, has spurred horticulturalists to develop many columbine
cultivars. The subject of this article is a relatively new hybrid
called Origami Red & White’, which flowers for the incredibly long
period of three months! It also boasts resistance to hungry
rabbits and deer! The plant grows to about thirty five
centimetres in height, and the blooms are about eight centimetres in
Columbines are members of the buttercup family (Ranunculaceae). The common
name is derived from the Latin word columba
which means “dove”, or columbnus which means “like a dove”. This refers to
the curved spurs which resemble (perhaps) a small clustering of the
birds. By contrast, the genus name Aquilegia comes from the Latin word
aquilinum which means “like an eagle”, since the
aforementioned spurs look like the talons of an eagle. Obviously,
the spur structures are interpreted very differently by
observers. Doves are eagle food!
At an early stage of development, a columbine bud is enclosed by the
green sepals (modified leaves)
that will eventually turn red to form the outer ring of the mature
flower, seen above.
Several days later, these sepals are tinged with pink, and the bud’s
distinctive spurs have grown long enough to be clearly visible.
Many flowers have nondescript leaves, but I find those of the columbine
to be particularly photogenic. Their finely veined, smooth edged,
three-lobed structure is unusual, and quite striking.
The two photomicrographs shown below reveal a leaf’s cellular
structure. The cells composing the lighter veins contain little
or no green chlorophyll.
Notice in the following image, how the more deeply coloured, developing
sepals seem to wrap around the base of each pale green spur.
Eventually, both the sepals, and spurs take on their final deep red
colour. The only exception is the white tip of the sepal.
Buds tend to face down, with the bulbous spur tips at the top of the
As a bud opens to reveal the mature flower, it bends so that the floral
tube is in a roughly horizontal position.
The reason for the columbine’s popularity is easy to see in the images
below. The flower’s striking form and colouration are highlighted
against a mass of bright green leaves. Note that the bloom’s
inner ring is composed of five white edged petals, while the outer ring is
formed by five bright red sepals.
Although a cursory inspection may give the impression that the five
spurs are extensions of the red sepals, in fact, they are the
extensions of the five white petals!
This is clearly shown in the image below.
Each of the flower’s spurs is a hollow, elongated tube which contains
specialized cells that secrete nectar. The spur forms a reservoir
for the nectar which collects in both the tube, and in the knob-like
bulge at the tip. (The surface tension of the liquid holds it in
these locations even if the flower is positioned at an angle where
gravity would tend to cause the nectar to flow out of the spur.)
A closer view of the bulbous tips of spurs shows that they are
translucent. Notice that both spurs and bulbs are covered with
exceedingly fine hairs.
Under the microscope, the unusual colouration, and cellular structure
of one of the bulbs are evident. The third image is taken at a
much higher magnification than the first two.
Two photomicrographs follow that show the tube of a spur. The
image on the right was altered in Photoshop
by using ‘auto-levels’ to enhance contrast.
Notice the red sepals in the image below.
Under the microscope, the roughly spherical cells that form the sepal’s
structure can be seen.
The surface of most sepals contains small imperfections. One such
blemish can be seen at two different magnifications in the images that
The cellular structure of one of the flower’s white petals can be seen
in the photomicrograph below.
In certain lighting situations, the rough surfaces of both sepals and
petals are evident. Notice that the base of each white petal
transforms into the red tubular form of a spur.
When a flower first opens, each of its anthers
(male pollen producing organs) is enclosed in an oval ‘anther cap’. The
photomicrograph at right shows one of these caps. The image on
the left also shows the light green filaments
that support the anthers.
After a short time (several hours to a day), these caps disintegrate to
reveal the yellow, pollen encrusted anthers beneath. In most
flowers, this process starts at the centre of the cluster of stamens,
and moves outward.
A photomicrograph of a pollen covered anther, and its supporting
filament, can be seen below.
Two images of a filament follow. The image on the left uses
normal dark-ground illumination. In the right image, the
dark-ground condenser has been moved slightly off-axis to give a better
impression of the three-dimensional character of the surface.
A higher magnification view of an anther reveals that columbine pollen
grains are roughly ellipsoidal in shape.
Within the central area of the clump of stamens, there are many pale
green, sharply tipped pistils,
each of which is composed of a stigma
(female pollen accepting organ), supported by a style.
The stigma tip can be seen below. It is unusual in that it has
none of the hairy protuberances possessed by those of most other
On the other hand, the ovary, which is connected to the base of the
short style, has many long hairs covering its surface.
Higher magnification reveals the hairs’ bulbous bottoms and thin
tips. (The purple colour seen in the first image is an anomaly
caused by using ‘auto-levels’ to increase contrast.)
The two images of an ovary that follow show the result of sliding the
dark-ground condenser off-axis.
If the ovary is cut open, it can be seen to contain many egg-shaped,
The columbine’s structure has over time, evolved in order to control
which pollinators can facilitate its reproductive success. In
order to obtain the nectar stored in spurs, the insect or bird must
have an appendage long enough to penetrate to the position of the
nectar. Different species of columbine have different spur
lengths, and this tends to ‘pick’ particular pollinators.
Butterflies, hummingbirds, and even bees are possible pollinators for
particular columbine species. As an insect’s or bird’s head is
pushed into a spur to obtain the nectar, parts of its body come in
contact with the mass of pollen covered anthers positioned above the
spurs. When this pollen is then carried to another plant,
cross-fertilization is accomplished.
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.
Columbines—Elegant Flowers Spurred to
Microscopy UK or their contributors.
Published in the
January 2008 edition of Micscape.
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