Sinningia defoliata

A fascinating species with a remarkable leaf.  Flowers are borne directly from the tuber, usually after any leaves have fallen.

1. The Leaf
2. ... red
3. The Seedling
4. Where's the Stem?
5. Flowerstalk is a raceme
6. Propagation
7. How to make the leaf stand up
8. Hormones in control
9. Dale Martens grows this species, with closeups
10. This species with other unifoliate sinningias (on a different page)
11. Miami 2007 (picture of Peter's plant and link to picture of Bill's)
12. Feature table
13. External links
14. Publication and etymology

Sinningia defoliata blooms directly from the tuber.  The peduncle appears to arise from the tuber itself, and not from a stem anchored to the tuber (as is the case with most sinningias).  Often, when it blooms, the plant is leafless.

In this, it resembles two other species, S. helioana ("Santa Teresa") and S. stapelioides ("Pancas").

Another similarity: in all three species, the leaves, instead of being borne on a conspicuous stem, appear to sprout from the tuber.  In S. helioana and S. stapelioides, the leaf is at the end of what appears to be a long petiole (but isn't).  In S. defoliata, the leaf barely has anything resembling a petiole either, as the leaf blade looks like it is attached to the tuber.

As we will see below, appearances can be deceiving.

These three species, along with S. tuberosa, often bear just one leaf during the growing season.  A comparison of these four species in unifoliate habit can be seen here.

The Leaf

The leaf in this picture is almost 30 cm [12 inches] long.  That is, it was that long in May 2007.  It has long since been discarded by the plant.  Usually, but not always, the plant drops any leaves it has around the beginning of winter.

By autumn, the leaves of S. defoliata have begun to look ragged, particularly along the margins, very much like the leaf of a unifoliate streptocarpus.  Even under lights, a six-month-old leaf will show wear and tear.

Sinningia defoliata leaves will last a long time (years) when dried, even without any special arrangements at all (no press, no desiccant). See here for a picture.

Some sinningias produce new leaves with maroon or red backs.  This species is not usually one of them.

But here it is.

This species normally drops its leaf or leaves in mid-winter. This plant retained its one leaf until mid-August (mid-summer in California).

Very few sinningias show red on the front of the leaf.  This species is not normally one of them.

But here is the same late-sprouting leaf as in the picture above, photographed within a couple of minutes.  The plant has just finished blooming and setting seed.  The seed has just been harvested.

A new season is beginning.

Leaves and Flowers

No Leaves, Three Flowers

In 2006, the plant bloomed from the bare tuber.  Presumably, the absence of leaves makes the flowers stand out more, as in "resurrection lilies" (Zephyranthes carinata) or many rosaceous fruit trees (like plums) that bloom before they leaf out in the spring.

It is, however, noticeable that the inflorescence of S. defoliata is relatively short.  Unlike bees, hummingbirds are quite a bit larger than the flowers they pollinate.  It may be that the absence of foliage makes it easier for hummingbirds to get down far enough to reach the flower.  I have seen our local Anna's hummingbird (Calypte anna) insert its beak into the opening of a pendant tubular flower and then lift the corolla enough so that it could get its beak all the way in.

One Leaf, Many Flowers

In November 2007, the plant flowered without any indication that it was ready to discard the leaf.  Perhaps in the habitat of this species in Brazil, conditions in winter are dry enough that the leaf has already dropped by the time the plant blooms.

Growing From Seed

The easiest way to propagate this species is by sowing seed.  The seeds usually germinate readily and the plants are not especially difficult to grow under most conditions.  It is also interesting to watch the plant develop.

The Seedling

At first the seedling looks like it could be any sinningia. This picture shows a seedling of S. defoliata in its first year.  It has paired leaves just as most gesneriads from the Western Hemisphere do.

Where's the Stem?

This picture, taken in May 2008, shows a S. defoliata leaf about 11 cm [4 1/2 inches] long.  Note the little sprouts at the base of the leafstalk (on the right side of the leafstalk in the picture).  They look a lot like leaf buds, but it would be unusual for leaves to be coming out of another leaf's petiole.

The apparent petiole of another species, S. helioana, is actually a stem, even though the junction between the stem and the petiole is not easy to spot.  Here, in the case of S. defoliata, the whole assembly, from the leaf blade down to where it meets the tuber, appears to be one unit, that is, the leaf and its petiole.  But is it?

Here is a closeup of the leaf base.  Shoot buds are coming out of the tuber, while leaf buds are attached to the base of the "petiole".  Note the dry stub labelled "old shoot".  This is the remains of the previous year's leaf stalk.  The abscission layer, the point at which the previous year's leaf broke away from the tuber, was not at the junction with the tuber itself, but about 8 mm [3/8 inch] above it.

This stub probably represents the stem portion of the leafstalk.  It is (was) the portion from which the leaf buds emerged.  If this is correct, Sinningia defoliata has a stem, but a very short one.

Sure enough, closer examination of a Sinningia defoliata leaf just starting to expand indicates that it is one of several leaves on the compressed stem.  The leaves are arranged normally, in pairs, and one of the leaves grows while the others remain dormant.

One implication was that it might be possible to propagate S. defoliata vegetatively, by removing the leaf together with the stem portion.  The stem might root and form a tuber, while one or more of the other shoot buds seen in the picture might break dormancy and create new single-leaf stalks.

The Raceme Is On!

Most gesneriads bear their flowers in cymes, specifically, pair-flowered cymes.  Virtually all sinningias do.  The only case where it is ambiguous is when there is just one flower per axil, as with (for instance) S. "Black Hill". However, on the rare occasions where there are two flowers per axil, the second flower is in the standard pair-flower position, showing that these plants too have the pair-flowered cyme pattern.

This picture shows that Sinningia defoliata makes a raceme.  The two bottom flowers have opened first.  The top two buds will open later.  If this species had the normal gesneriad cyme, the top flower would have opened first.

This picture shows a slightly larger raceme. 

I have never observed secondary branching on a raceme of this species.  That is, each side branch from the primary raceme axis is a single pedicel bearing a single flower.

This picture shows a more complex raceme, with the structure somewhat tangled.  Even so, it can be analyzed to show that the bottom flowers open first.

The letters mark the paired flowers along the raceme, opening in sequence from the base of the raceme toward the tip.

A = first flowers visible in picture, now spent
B = next pair, now open, in female phase (stigma just visible in the lower flower)
C = next pair, now open, in male phase (anthers just visible). Male phase precedes female phase, so these flowers are younger than those in (B).
D = next pair, in bud
E = tip of the raceme, with several buds

This picture shows the bracts at the base of each pedicel. For their true size, see the picture at the top of this section.

This shows that the inflorescence of Sinningia defoliata is much like a normal stem.

Propagation

Two efforts at vegetative propagation are documented.

The first, from 2009-2010, is described here.  Experience gained in these trials permitted better results in a later effort, in 2015, which is described here.

Another Way of Growing This Species

In the past few years I have been growing Sinningia defoliata in front of a window, so that the light comes in from the side.  The result is that the primary leaf stands up vertically, with secondary leaves projecting forward.

In 2010 I removed the secondary leaves, while in 2011 I left them on.  In these 2011 pictures, the primary leaf is 38 cm [15 in] long.  The plant is growing in a 5-inch pot.

As shown in the seedling picture above, Sinningia defoliata seedlings have normal stems and leaves.  It is only when they mature that they switch to large single leaves.  The growth pattern is regulated by hormones.

In the case of Streptocarpus, the late Irwin Rosenblum showed that which type of leaf was created was under hormonal control (see references).  Unifoliate streps can be induced to make stems by application of certain plant hormones. 

Dale Martens grows this species

Dale Martens grew a plant from seed that I sent her -- under the name S. defoliata x 'Los Angeles', but (blush) turned out to be a selfing.  She grew it the same way she grows everything else, on a wick, from the moment she transplanted it out of the seedling tray.  Given the constant moisture, it never went dormant for two years and then bloomed.

As shown in the sequence of pictures below, the first bloom was on the juvenile growth, then from the tuber (just like a "normal" defoliata).  Finally, it appeared to be going dormant.

These pictures were taken in 2013.

• Above left: first bloom
• Above right: bloom from tuber
• Left: impending dormancy

Dale also provided me with pictures of the reproductive apparatus (or, to use the scientific term, "naughty bits").

• Right: anthers and pollen
• Below left: style, ovary, and nectaries, with perianth removed.
• Bottom left: corolla split to show the stamens
• Bottom right: back of anthers

At the 2007 Gesneriad Society convention in Miami, two plants of this species were exhibited, both having traveled 3000 miles to get there!  Bill Price's plant is shown on the Gesneriad Society website.  Peter Shalit's was equally striking, with fewer flowers but two large leaves, which makes the transportation accomplishment all the more impressive.

Bill's striking tuber-and-flowers plant brought up an interesting judging puzzle: How do you judge "cultural perfection" if there aren't any leaves?

The picture below is Peter's plant.

In 2010, Bill Price exhibited a sinningia collection which included a large Sinningia defoliata with five leaves.  Pictures of this plant can be seen here.

Feature table for Sinningia defoliata

External link

Publication

Malme, 1937, as Corytholoma defoliatum.  Chautems transferred it to Sinningia in 1990.

Etymology: from Latin de- ("off, down, away") + -folia ("leaf").
Not, presumably, "leafless" but rather "leaf dropper".
While most sinningias drop their leaves at some point, it is the habit of blooming while leafless that inspired the name.