A Close-up View of Little Princess Spirea
View of "Little Princess" Spirea
by Brian Johnston (Canada)
This plant is a hybrid of Japanese
Spirea which is native to Eastern Asia. The native plant, first
brought to North America in the 1870’s, is a small deciduous shrub that
grows to about 2 metres in height. By contrast, the hybrid Spiraea japonica ‘Little Princess’
barely reaches 0.5 metres at maturity. Although small in stature,
“Little Princess” Spirea certainly puts on a colourful display during
late spring and early summer. Its bright red and pink flowers,
each less than a centimetre in diameter, are held in almost flat
clusters referred to as corymbs. One such corymb can be seen in
the first image in the article.
Other views of the plant, showing
its variously shaped corymbs, and the emerald green of its lance-shaped
(lanceolate) leaves, can be seen below.
A new growth shoot is shown in the
following images. Notice that its leaves are a slightly lighter
green, and that a number of bud-stage corymbs are visible.
Spirea buds are almost perfectly
round, and as can be seen in the image on the right below, are
protected by a ring of light green sepals (modified leaves).
Some, but certainly not all of the
bud clusters, are associated with a leaflet. The one shown in the
image below has not completely unfurled.
As the time for blooming
approaches, the five green sepals begin to be pushed away by the
swelling petals that make up the flower’s corolla. The brilliant
red colour of the corollas makes a startling contrast with the deep
green of the surrounding foliage.
Closer views of the opening buds
reveal the strange thread-like fibers that run between the edges of
adjacent sepals. These threads obviously break when the enlarging
corolla pushes the sepals far enough apart.
Notice the intense hairiness of the
bud stalks, and the fused base of the sepals.
The images below show buds that are
hours from blooming. Notice that at this point, the sepals have
opened into 5-pointed stars.
In a given plant, the flower
clusters display a wide range of developmental stages.
A view from beneath the
flower-heads reveals the very light green stems of the plant.
Each blooming flower in the cluster
sends out a spray of stamens, longer than the diameter of the flower
itself. The multi-lobed pistil on the other hand, barely
protrudes above the corolla’s rim.
As the magnification increases, it
is eventually possible to get a better look at the anthers on the ends
of a flower’s exceedingly spindly filaments. It is also evident
that the anther’s possess two lobes.
The photomicrograph on the right
below shows a portion of a flower’s petal.
A higher magnification reveals its
Near the base of a petal, cells
contain darker spots of unknown origin.
Another area of the petal is coated
with ellipsoidal Spirea pollen grains.
Let’s look more closely at a
flower’s anthers. To begin, an anther is covered by what appears
to be a pinkish-red membrane.
This membrane disintegrates over a
period of several days to reveal the amazingly smaller, pollen covered
Three photomicrographs showing the
surface of the intact membrane can be seen below.
After the membrane has
disintegrated, the anther looks like this.
In the image below there is a very
dark red ring at the flower’s centre. This ring is composed of
the bases of the flower’s five petals. On the right is a
photomicrograph of one of these bases showing its dark red rectangular
Three higher magnification images
show these lobes in more detail. (The red radial structures on
the right in the first two images are filaments.)
The area further up the corolla
from the base has many seemingly transparent hairs growing from the
A flower’s stigma appears to have
The cellular structure of the top
of the supporting style can be seen in the images that follow.
A Spirea leaf is prominently veined
and has small, irregularly shaped, pointed lobes.
The undersides of leaves are much
lighter in colour, and the raised veining is more prominent.
Views of the top and bottom of a
leaf follow. The combination of the raised veins, and much finer
pattern between them makes for an extremely attractive leaf.
Higher magnification shows the
subsidiary veining more clearly. Notice the interesting tiny
white dot at the tip of each of the leaf’s lobes.
The shape of these lob tips varies
Photomicrographs of the subsidiary
veining shows the random nature of the pattern more clearly.
Here, the strange shape of the
cells that compose a vein is shown.
In some areas, exceedingly long
fine hairs grow from the surface of a vein.
‘Little Princess’ is a perfect example of an
“ornamental” plant. It continues to be interesting no matter how
closely you examine it!
The low magnification, (to 1:1),
macro-photographs were taken using a 13 megapixel Canon 5D full frame
DSLR, using a Canon EF 180 mm 1:3.5 L Macro lens.
An 10 megapixel Canon 40D DSLR,
equipped with a specialized high magnification (1x to 5x) Canon macro
lens, the MP-E 65 mm 1:2.8, was used to take the remainder of the
The photomicrographs were taken
using 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 August
2011 edition of Micscape.
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