A Close-up View of the Toad-Lily

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.

Tricyrtis 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 spots.

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. Each 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 stigmas).

In the image below, a couple of the flower’s flattened, oval anthers can be seen hanging beneath the styles.

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 surface.

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 forked lobes.

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 fertilization process.

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 conditions.

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 distinctly yellow.

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 image below.

The green colouration of the flower’s spurs is the main differentiating feature between the two forms.

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!

Photographic Equipment

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 images.

Further Information

Origin of the common name Toad-Lily: http://www.paghat.com/toadlily.html

A Flower Garden of Macroscopic Delights

A complete graphical index of all of my flower articles can be found here.

The Colourful World of Chemical Crystals

A complete graphical index of all of my crystal articles can be found here.

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