Close-up View of a
by Brian Johnston (Canada)
camara is native to the tropical regions of the world, where it
exists as a rugged evergreen shrub that grows as tall as 2 m. The
cultivar studied in this article couldn’t be more different! For
more than 500 years, artificial hybrids have been developed in Europe,
and other locations, until today at least 100 different forms and
varieties exist throughout the world. In most hybrids, the flower
colour changes with age, from the original yellow, to pink, white, or
red, depending on the variety. Some hybrids however, such as the
one photographed here, have a yellow band at the mouth of the corolla
tube which is thought to be a visual cue to pollinating insects.
These hybrids have a constant colouration.
The cultivar Lantana camara ‘Lemon
Cream’ is diminutive in size. The flower head shown above
is approximately 3.5 cm in diameter, and the plant is 15 cm high.
Two bud-stage flowerheads, called umbels
can be seen in the image below. Notice the ring of green bracts
(modified leaves) beneath each umbel. The bracts form the
Above the involucre bracts, there is a mound composed of smaller
bracts. There is one of these bracts for each flower in the
flowerhead. If you look closely, you can see a white flower bud
above each bract, near the base of the flowerhead.
As time passes, these white, to pale-yellow buds increase in size until
they dwarf their associated bracts. The buds that form the
outermost ring of the flowerhead are the largest, and these have a
darker yellow colouration. Some references describe Lantana buds as having a square
shape, but to me they appear like miniature bow-ties!
When the flowers finally bloom, they do so in order from the outer ring
to the centre of the flowerhead. The fused petal tube, (corolla tube), has, as mentioned
earlier, a yellow ring at the point where the narrow tube flares out to
form the trumpet-shaped flower top.
Two photomicrographs showing the cellular structure of one of the
flower’s fringe “petals” can be seen below. The central cells
appear spherical in shape, while those at the petal’s edge appear
The lower surface of a petal is covered with long hairs that appear, at
higher magnification, to have extremely small projections on their
Different developmental stages can be seen in the flowerheads shown
below. Notice that no reproductive structures are visible in the
fully mature flowers. These are hidden deep within the corolla
tube of the flower and are therefore inaccessible to insects without a
A closer view shows additional details of each stage, from bud to
Viewed from beneath, the ring of involucre bracts can be seen
clearly. Notice the length of each flower’s corolla tube.
Bright lemon-yellow flowerheads contrast with the surrounding green
Positioned deep within the corolla tube is the flower’s pistil. At the top is the stigma which accepts pollen from a
visiting insect. Beneath the stigma is the style that supports it. Older
styles have a red colour (left), while younger ones are pale green
The photomicrograph on the left below, shows a higher magnification
view of the many hair-like projections on the stigma’s surface that
help catch, and retain pollen grains. The image on the right
shows the base of the style, and the swollen ovary (seed producing
Lantana leaves are
lance-shaped (lanceolate), and
have a glossy green upper surface with an attractive vein pattern.
The lower surfaces of leaves are covered with relatively long, sharply
pointed hairs which are concentrated on the prominent veins. In
the last image, pollen grains can be seen clinging to the surface of
Lantana camara ‘Lemon Cream’
has unusually shaped buds, and colourful flowerheads that make it an
attractive garden flower.
Mystery – “The case of the
missing stamens.” Readers may wonder why I failed to
include photomicrographs of the flower’s male stamens in this
article. It was my intention to do so, but I couldn’t find
any! I carefully dissected several corolla tubes, expecting to
find anthers with their filaments attached to the inner corolla
tube. They simply weren’t there!
Approximately half of the photographs in the article were taken with an
eight megapixel Canon 20D DSLR and Canon EF 100 mm f 2.8 Macro
lens. An eight megapixel Sony CyberShot DSC-F 828 equipped with
achromatic close-up lenses (Canon 250D, Nikon 6T, and Sony VCL-M3358
used singly, or in combination), was used to take the remainder of the
The photomicrographs were taken with a Leitz SM-Pol microscope (using a
dark ground condenser), and the Coolpix 4500.
Notes on poisoning – Lantana camara
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
November 2009 edition of Micscape.
Please report any Web problems or
offer general comments to the Micscape
Micscape is the on-line monthly magazine
of the Microscopy UK web
site at Microscopy-UK
Onview.net Ltd, Microscopy-UK, and all contributors 1995 onwards. All
rights reserved. Main site is at www.microscopy-uk.org.uk
with full mirror at www.microscopy-uk.net .