View of the
The beginning of October is a
frugal period when searching for interesting plants at my local garden
centre. The first frost may be only weeks away, and the huge
choice available in the summer has now dwindled to Asters and
Pansies. What a pleasant surprise then, to come upon this
spectacular jewel of a flower! In fact, the Toad-Lily is renowned
for its late flowering, and its ability to grow happily in the
shade. Shady locations delay the start of flowering, and cause
the season to extend into November, if weather permits.
is a genus of perennials belonging to the Convallariaceae (Lily of the Valley)
family. (Historically, the genus was included in the family Liliaceae.) Plants are native
to moist woodlands from the Eastern Himalayas to the Philippines, and
in Taiwan and Japan. The species studied in this article, Tricyrtis formosana, is a hybrid
based upon wild plants growing in the forests of Taiwan.
The Toad-Lily is described as being
a stoloniferous species.
This means that in addition to reproduction by fertilization, it can
also reproduce by producing horizontal stems which grow at, or below
the surface. At the ends of these stolons (or runners as they are
sometimes called), or at nodes along their length, new plants (clones) can begin to grow.
Why is Toad-Lily the common name of
the plant? A Philippine species Tricyrtis
imeldae (named after Imelda, wife of the dictator Ferdinand
Marcos), grows in a region that is the home of the Tasaday tribe.
Tasaday hunters would crush the plant’s parts, and leave the scented
juice on their hands in order to attract frogs and toads for
food. It is now believed that the entire description was an
elaborate hoax, and that the idea that one could attract toads by the
scent of the plant was nonsense. This reappraisal of the
situation has done nothing however to deter the use of the amusing
common name – so Toad-Lily it is! Worse still, the name has
become a catch-all for most members of the genus. (To read the
complete story, see the link at the end of the article.)
Dark Form of Tricyrtis formosana
While looking for a plant to
photograph, I noticed that although two containers were labeled as Tricyrtis formosana ‘Dark Lily’,
the flowers were noticeably different in colouration. It was only
when I brought them home, and did some investigating, that I found that
there are two forms of the species – dark and light. In this
article, we’ll look at the dark form first. The plant shown below
is about 25 centimetres in height and its blooms are approximately 2.5
centimetres in diameter. Leaves are alternately positioned on the
stem, and have an ovate shape.
Buds and stalks are
liberally covered with fine hairs. Notice in the left image, that
another tiny bud is growing from the stalk just beneath the
first. A single leaflet cups this second bud.
Higher magnification reveals the
roughness of the bud’s surface, and that even the tiny bud is hairy.
Each flower possesses three outer
sepals that are wider than its three inner petals. Both are
white, and are liberally covered with irregularly shaped, deep purple
A closer look at a bloom reveals
that the base of each petal and sepal is a deep yellow colour.
(Most references on this species describe the flower’s sepals and
petals as tepals, the collective term used when the two are
indistinguishable from one another. In the plant studied here,
the two are certainly distinguishable, and so I will not use the tepal
descriptor.) One of the unusual structures that can be seen in
the images that follow, is the umbrella-shaped assembly of three forked
styles that rises above the sepals and petals. Beneath this
assembly, several anthers and their supporting filaments are visible.
The two images below show the
structural difference between a sepal, and a petal in the
Toad-Lily. An outer sepal is wider, less spotted on its outer
surface, and has more, but less prominent veining. At the base of
the sepal there is a bi-lobed, bright red, swollen spur. Since
there are three sepals in the flower, there are three of these spurs –
hence the genus name Tricyrtis.
of the narrower petals is spotted on its outer surface, and
possesses a very distinctive, single, raised, rib-like vein.
As we move closer, it is evident
that the petal’s main vein has two less pronounced veins paralleling it.
As we will see later, the dark red
colour of the swollen spur at the base of a sepal is indicative of the
dark form of this Toad-Lily. The images that follow show the
upright position of the sepals at one stage as a flower booms.
Notice the overarching structure formed by the pistils (styles and
In the image below, a couple of the
flower’s flattened, oval anthers can be seen hanging beneath the
Depending on the viewing angle, it
may sometimes be difficult to see that the spur of each sepal does in
fact have two lobes. Even these lobes have very tiny hairs
growing from their surfaces.
The inner surface of one of the
sepals is shown below
At its base, the sepal has a yellow
colour. At the top of the image on the left, the sepal curves to
form a tube which ends in the swollen spur seen earlier. The
image on the right resolves the cellular structure of the sepal’s inner
Closer views from above the flower
reveal that the styles are covered by stalked, spherical, glistening
glands. Note also that the flower possesses six anthers and
filaments – three between the
styles, and three beneath the
The top surface of one of
the anthers (male pollen producing organs) can be seen below.
Anthers face downward toward the base of the flower. The upper
surface is mottled, and has a faint mauve hue.
Two additional images follow,
showing the upper surface of an anther, and the point of connection to
its supporting filament.
Looking up from below at the lower
surface of an anther reveals that it is divided into two raised, dark
pads, by a lighter area. The light brown granular material on the
pads’ surfaces is composed of pollen grains. The white oval seen
in the upper right of each image is the active surface of one of the
flower’s stigmas (pollen accepting organs).
To me, the structure of the
Toad-Lily’s reproductive organs is reminiscent of that of the Passion
Flower. Both have stigmas and anthers raised above the
flower. In the Passion Flower, both are attached to a supporting
central column, whereas in the Toad-Lily, long styles and filaments
hold the reproductive organs aloft.
The three images that follow show
the gold coloured, spherical glands that line the edges of the flower’s
styles. The spheres are composed of sticky liquid droplets
enclosed by thin spherical membranes. Since the droplets are
different sizes, I suppose that the membrane stretches as the gland
forces more liquid into the balloon-like structure.
In the image below of one of the
flower’s six stigma pads, it is possible to see the stubby gland-like
hairs that cover its surface. These hairs increase its surface
area, and thus increase its ability to capture and retain pollen grains
transported to it by visiting insects.
By removing several
obscuring structures, the make-up of the flower’s central ‘stalk’
becomes visible. Six long, columnar, red-spotted filaments
surround the light green ovary.
If some of these filaments are
removed as well, the three-compartment ovary becomes visible. The
ovary ends where the transition to the three styles begins – the
unspotted colourless band.
Here, finally, are several
additional images showing the interesting glandular structures on a
flower’s styles. It is likely that the liquid exuded by these
glands is prized by visiting insects, and thus helps in the
Light Form of Tricyrtis formosana
As you can see from the image
below, the two forms are identical in structure. The light form
however has a pinker colouration, with less intense spots.
In fact, if the two plants are in
the bud stage, they are indistinguishable. Notice the single
leaflet that is positioned on the stem beneath each group of two buds.
As a bud develops, the swollen
spurs appear at a relatively late stage. Notice that this light
form has bi-lobed green spurs instead of the red of the previous
form. The second image shows the very start of the blooming
process where the sepals separate to reveal the petals beneath.
Some of the leaves of this form
have lighter edges, but this might be due to dry environmental
The base colour of the dark form is
white. Here it is pink. Notice that the spots on sepals and
petals are smaller and more numerous.
Other than the difference in
colouration, blooms of the two forms are identical.
Here again, the base of a sepal is
Compared with the earlier form, the
anthers are brownish rather than mauve. Those readers with sharp
eyes may notice that the stalks of the spherical glands are longer here.
The column formed by the flower’s
styles is definitely more yellowish in the light form, while the sepals
and petals tend toward the pink.
This is easier to see in the closer
The green colouration of the
flower’s spurs is the main differentiating feature between the two
Most gardening sites on the
internet suggest planting the Toad-Lily in locations where it can be
examined up-close in order to facilitate viewing of its spectacular
flowers. I hope that this even closer view has whetted your
appetite to investigate the plant on your own!
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 8 megapixel Canon 20D 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 common name Toad-Lily:
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
January 2010 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 .