A Close-up View of the Torch Lily

Kniphofia uvaria 'Alcazar'

by Brian Johnston   (Canada)

The shape and colour of Kniphofia uvaria’s extraordinary bloom were the inspiration for all three of its common names, Red Hot Poker, Torch Lily, and Tritoma.  Originally found in Madagascar and tropical South Africa, the plant was brought to England in the early eighteenth century, and over the years many cultivars have been produced.  One of these, ‘Alcazar’, is the subject of this article.

Kniphofia  (named in honour of Johannes Hieronymus Kniphof (1704-1763) , a professor of medicine at Erfurt University in Germany), is a genus of plants in the Asphodelaceae family.  Interestingly, the genus Kniphofia is closely related to the genus Aloe of hand-lotion fame.  Translated from the Arabic, the cultivar name ‘Alcazar’ means Spanish fortress or palace.

The first image in the article shows the structure of a Torch Lily inflorescence.  Keep in mind that this colourful flower-head is held aloft by a one metre long sturdy green stem!  Most of the bloom is at the bud-stage.  Only a few flowers have bloomed at the very base of the cone-shaped structure.  Botanists refer to such a flower-head as a “dense indeterminant spikiform raceme”!  This particular cultivar displays shades of yellow and orange, which some describe as “hot coloured” or the colour of “burning embers”.

To show the blooming process, here are two images of the flower-head taken four days apart.  As you can see, its flowers bloom from bottom to top.  The flower-head appears at its “best” near the beginning of the process.  At later stages, the many wilting, dead flowers detract from its striking and unusual structure.  (The leaves seen in the background of the image on the right belong to a second plant that has been raised vertically.  The leaves of the plant don’t grow as high as the flower-head.)

In the image that follows, each elongated bud (~ 2.5  cm) in the lowermost ring has opened to reveal the flower’s six short (~3 mm), rounded petal lobes.  Extending down from the open end of the flower are 6 stamens, and a single pistil.

The two images below show the flowers’ oval, yellow anthers, and their supporting white filaments.  At this early stage, no pollen is present on the anthers’ surfaces.

In this species, the pre-blooming stage is quite simply, spectacular!  The many tubular, almost banana-like buds are slightly grooved, and have attractive grayish highlights.

Closer views reveal the subtle shading displayed by the drooping structures.

In the first photograph below, the stamens that project from the newly opened flowers are immature, and yellow in colour.  In the last two images, flowers that opened earlier (lower in the flower-head) possess anthers that are beige or brown in colour.  These have begun to shed pollen.

Let’s look first at the immature anthers (male pollen producing organs).  Each 6-petaled flower possesses 6 anthers positioned at the ends of supporting white filaments. 

Higher magnification reveals that each anther has longitudinal grooves on its “upper” surface.  Of course, since the flower’s open end faces down, the anther’s  “upper” surface faces in the same direction.

Even higher magnification macro-photographs show that the anther is divided into lobes.  Individual cells can be resolved in the image on the right.

Eventually, each anther begins to shed pollen, a process referred to as dehiscing.  At this point, the anthers are no longer yellow, but have turned a reddish-brown.  (The image on the right shows “younger” anthers that have just begun the process.)  In both images the long, white, rod-like structures that extend beyond the stamens are pistils.

At the limit of the magnification possible with my macro-photographic equipment, individual pollen grains are visible on an anther’s surface.

By using a microscope, we can get a still clearer view of the back of an anther, with its point of attachment to the filament.

A photomicrograph follows that makes use of dark-ground illumination to show several Torch Lily pollen grains.  They appear ellipsoidal, with pointed ends.

To show only the previous image would not give a true picture of the shape of these pollen grains however.  In fact, they are remarkably dissimilar in shape from one sample to the next.  Take for example the six grains in the following photomicrograph.  One is almost spherical, two are ellipsoidal, one is ellipsoidal with a “dimple”, and two are strangely triangular in shape, also “dimpled”.

At a much higher magnification, surface detail can be resolved.

A single pistil, composed of a stigma (pollen accepting organ) and its supporting filament, extends farther out of the open flowers than do the stamens.  Since the flowers face down, the abundant viscous nectar flows to the tip of the stigma and drips from it.  The droplet in the image hides the stigma itself, which can be seen at a higher magnification in the image on the right.  Notice the stocky, hair-like projections that cover the stigma’s surface.  These help to retain pollen grains.

In the image below, the flower-head has reached the age where its lowermost flowers have begun to die, and disintegrate.  Instead of falling off however, they remain in position – glued in place by the thick coating of sticky nectar that has dripped or flowed from higher blooming flowers under the influence of gravity.

On the left below is an image showing the cellular structure of the fused, or tubular portion of a flower’s petals.  Several pollen grains can be seen adhering to the surface.  On the right is a photomicrograph showing the stomata and associated guard cells that control gas flow into and out of a leaf’s underside.

A much higher magnification was used to produce the two images that follow, showing the surface of a fused flower tube, and bubbles that have formed in the coating of nectar on its surface.

Finally, here are two views showing why a Torch-Lily’s flower-head becomes less visually appealing with age.  As time passes, more and more decaying flower material accumulates, detracting from the inflorescence’s natural beauty.  Most gardeners remove dead flowers from the flower-head to prevent this from occurring.

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.

The photomicrographs were taken using a Leitz SM-Pol microscope (using dark ground and phase contrast condensers), and the Coolpix 4500.

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.

 All comments to the author Brian Johnston are welcomed.

Microscopy UK Front Page
Micscape Magazine
Article Library

© Microscopy UK or their contributors.

Published in the August 2009 edition of Micscape.
Please report any Web problems or offer general comments to the Micscape Editor.
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 .