Sinningia defoliata

  1. The Leaf
  2. The Seedling
  3. Where's the Stem?
  4. Flowerstalk is a raceme
  5. Propagation
  6. How to make the leaf stand up
  7. Hormones in control
  8. Miami 2007 (picture of Peter's plant and link to picture of Bill's)
  9. Feature table
  10. External links
  11. 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 another species, S. helioana ("Santa Teresa").  Another similarity: in both species, the leaves, instead of being borne on a conspicuous stem, appear to sprout from the tuber.  In S. helioana, 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.



 

The Leaf

The leaf in this picture is almost 30 cm [12 inches] long.  Or rather, was, 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 rather ragged and ratty, 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.



 

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 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.



 

The Seedling

This picture shows a seedling of S. defoliata.  At this stage, the leaves look like they could be any sinningia.



 

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 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.

It's a Raceme!

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

The full account of Sinningia defoliata propagation, by a couple of different types of cutting, is on a separate page.

One result, in early June 2008, was the observation above about a dormant leaf starting to expand once the "boss leaf" was removed.  This picture shows the base of the stem, with one of a pair of leaves expanding to take over the "boss" role, while the other remains small.  Above the stem is the cratered stub of the previous year's growth.  To the right of and slightly below the stem is the residue of an earlier year's stem.

[This picture was taken 9 June 2008, 12 days after the previous boss leaf was removed.]

I know what you're thinking.  Who cares? Just trust me on this: really cool stuff.



 

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.



 

Hormones in control

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



Feature table for Sinningia defoliata

Plant Description

Growth Determinate, sort of
Habit Extremely compressed stem(s), with only one leaf per stem expanding.  Flowerstalks grow directly from tuber
Leaves Light green.  Upper surface slightly sticky.
Dormancy Leaves deciduous, with compressed-stem stumps remaining on tuber.  Dormancy may be very short -- sometimes blooming lasts until new leaf growth begins.  On the other hand, dormancy may last 6 months.  One must be patient! Some of my tubers do not break dormancy until June (beginning of summer).

Dale Martens grows her plant on a wick, and reports [2013] that it has never gone dormant.

Flowering

Season According to Appendix 1 in Perret et al. [see references] S. defoliata blooms in August-October in Brazil.  This is late winter and early spring there.  Mine usually blooms in autumn or winter.  The plants exhibited by Bill Price and Peter Shalit in Miami 2007 were obviously blooming in mid-summer.  Growing under lights may disrupt the normal blooming schedule.  My plants (whether indoors or outdoors) often don't come out of dormancy until summer solstice (mid-June).
Flower Tubular, red

Horticultural aspects

Hardiness A plant I put outdoors survived 28 F [-2 C] without damage, not even to the leaves.  However, the plant did not bloom, even though it had done so in previous years.
Propagation From seed is easiest, but propagation by cuttings has been done.
Problems and pests Mildew on one plant out of three, one year
Recommended? Highly!  The single leaf appearing to grow directly from the tuber is a great conversation piece, even when the plant is not in bloom.  When it is in bloom, it's even more interesting!  More people should grow this species.  The only downside is that the horizontal leaf takes up a lot of room under lights.  Positioning the plant in front of a window, so that the light comes from the side, can result in a vertical leaf, which is very striking.

Botany

Taxonomic group The second core group of the Corytholoma clade.


External links

Mauro Peixoto's web site has a page on S. defoliata, including a picture of a multi-leafed plant taken by (and presumably grown by) Dave Zaitlin.

Ron Myhr's web site has a picture of a Smithsonian plant blooming with what appears to be four leaves.

Miami 2007

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.

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 this applies to most sinningias, it is the habit of blooming while leafless that inspired the name.