Technical Overview of the Genus Sinningia

For a basic introduction to sinningias, see here.

The Gesneriad Family

Sinningia is a genus within the family Gesneriaceae.  At the risk of vastly oversimplifying, we can say that the gesneriad family belongs to a group of families in the flowering plants characterized by

In almost all gesneriads, the wall separating the two carpels is partially or completely absent, so that the interior of the ovary and resulting fruit is a single chamber, called a locule.  The page which discusses gesneriad fruits has a lot more information and a picture.

Within the Gesneriad Family

The gesneriad family is composed of two subfamilies.  Or three.  Or four.  Or more, depending on what's been published in the last twenty-four hours.

The first traditional subfamily used to be called the Cyrtandroideae.  This was a reasonably appropriate name since Cyrtandra is the largest genus in the subfamily and in fact in the gesneriad family as a whole.  This name was published (in slightly different form) in 1835.

Unfortunately, another name for the subfamily was published in 1832 and promptly forgotten.  The robotic laws of botanical nomenclature require that it displace a name that's been used for a long time, so the subfamily is now named the Didymocarpoideae.  Say what?  Didymocarpus?  Really?

Well, the bright side is that plant subfamily names don't appear on plant labels.

The Didymocarpoideae are mostly confined to the eastern hemisphere (Asia, Africa, Australia, and Europe).  It is distinguished by the accrescent cotyledon.  That is, one of the two cotyledons increases in size, while the other withers and drops off the seedling stem.  In some species, such as the unifoliate streptocarpus, this cotyledon is all the leaf the plant ever has.

The other traditional subfamily, the Gesnerioideae, is mostly confined to the western hemisphere (North and South America and the islands of the Caribbean), plus a few species in the south Pacific.  It is to this subfamily that the genus Sinningia belongs.

Two other subfamilies have been proposed.  See the table of gesneriad subfamilies.

The Sinningia alliance

A tribe is an optional taxon between family and genus.  Plant families can contain tribes, and tribes contain genera.  The genus Sinnningia and its two allies used to constitute a tribe named after the primary genus of the tribe.

However, after what seems to me an arbitrary reranking of various subdivisions of the gesneriad family, this group of genera was demoted to a subtribe.  The unpleasant effect of that was to expose the group to the tyranny of taxonomical nomenclature.  Long ago, a subtribe had been created for this group of species, with a name which is now irrelevant since it references an obsolete and forgotten genus name.

Therefore I do without the word tribe and use the informal word alliance instead.  This alliance contains three genera: Sinningia, Vanhouttea, and Paliavana.


Attribute Usual situation Exceptions
Distribution Southeastern quarter of Brazil A few species (most notably, S. incarnata) outside Brazil (see the description of the Corytholoma clade)
Tuber Most species have a tuber -- that is, a modified stem from which the plant sprouts in the spring. S. schiffneri and S. gerdtiana do not have a tuber
Stem Stems are usually deciduous, breaking off cleanly from the tuber in late autumn. In a number of species, this does not happen if the weather is not cold or dry enough. S. reitzii, S. mauroana, and S. sp. "Black Hill" have perennial stems retained through the winter.  If the stem is cut back, the stump remains.  Even though they have deciduous stems, S. gigantifolia, S. cochlearis, and S. macrostachya have "stump stems" attached to the tuber which get a little longer every year.
Leaves per node The general rule is two leaves per node.  Some species can have three leaves per node (a "whorl").  This can either be the general rule for the species (e.g. S. polyantha) or an occasional variation. A few species, such as S. defoliata and S. stapelioides have just one leaf per stem, and thus one per node.
Nodes per stem Some species have a fixed number of nodes per stem, usually two or three.  A larger number of species have stems with an indeterminate number of nodes. S. defoliata and S. helioana hide their nodes.  The leaves appear to grow directly from the tuber, but in actuality, real stems are present but either inconspicuous or disguised.
Flower placement Those sinningias with a fixed number of leaves bear flowers either at the uppermost node or on a terminal peduncle. Species with an indeterminate stem flower in the axils of leaves or bracts on that stem. S. defoliata and S. helioana flower directly from the tuber.
Pollination Most sinningias are pollinated by hummingbirds.  Most of the remainder are pollinated by bees. S. tubiflora is pollinated by moths.  S. brasiliensis is most likely pollinated by bats.  S. concinna, S. pusilla, and S. muscicola ("Rio das Pedras") are probably pollinated by small butterflies.
Flower color Usually red, orange, or magenta. Bee pollinated sinningias usually have purple flowers or white flowers with purple markings. S. sulcata has yellow flowers.  There is a yellow-flowered form of S. aggregata, and a white-flowered form of S. cardinalis.
Flower organization The petals are always united into a corolla tube (as is the case for the entire gesneriad family). There are four stamens, with the anthers joined into a rectangle.  
Flower shape The most common shape is a funnel-form tube, with or without flaring lobes, with or without a galea. Some bee flowers, including those of the genus Paliavana are campanulate ("slipper flowers").
Anthers Four, combined into a rectangle  
Stigmas One, maturing after the anthers  
Fruit Dry capsule, with one internal chamber. The fruit dehisces (splits open) down the middle of each carpel. Since gesneriad carpels are "top" and "bottom", the openings are along the top and bottom of the fruit. The tip or beak of the fruit is often the last part of the split to let go, so that the seeds do not all get shaken out at once. The fruit of S. gerdtiana opens like a duck's bill, as can be seen in a picture.
Ecology Many sinningias are lithophytic, growing on rocky cliffs or hillsides.  Some sinningias (most of the species of the Corytholoma core group) grow in meadows. S. cooperi and S. douglasii are epiphytic.  S. polyantha grows in sandy areas near the ocean.  A few species (e.g., S. gigantifolia, S. richii, and S. barbata) grow on the floor of montane or tropical forests.

Establishment of the Genus Sinningia

The following passage (with minor spelling corrections) is excerpted from the 1988 Sinningia register of the American Gloxinia and Gesneriad Society.

The genus Sinningia was named for Wilhelm Sinning (1792-1874), gardener of the Botanical Garden of the University of Bonn from about 1818-1846.  He served as instructor in Botany from 1847-1857, and in Horticulture from 1852 until his death in 1874.  In 1825 Wilhelm Sinning, in collaboration with Theodore Friedrich Ludwig Nees von Esenbeck... edited a volume entitled A Collection of Beautiful Flowering Plants.  Table 54 in this book is a colored lithograph of Sinningia helleri Nees.

[The Nees attached to the name Sinningia is Christian Gottfried Daniel Nees von Esenbeck (1776-1858), brother of the above-mentioned Theodore.]

H. E. Moore Jr. proposed in November 1973 uniting the genera Rechsteineria and XGloxinera with Sinningia.  This has been adopted.  All XGloxinera names found in the literature are [...] Sinningia interspecific hybrids.

[The author of the 1988 Sinningia register was the then AGGS Registrar, Jimmy Dates.]

Related Genera: Paliavana and Vanhouttea

The other two genera of the Sinningia alliance are Paliavana and Vanhouttea.  Both are shrubby species with no tubers.  Paliavanas have campanulate (bell-shaped) flowers pollinated by bees or bats, while vanhoutteas have red tubular or funnel-shaped flowers pollinated by hummingbirds.

Unfortunately, it appears from molecular data that these genera may not hold up.  Some of these species seem to be more closely related to some sinningias than they are to one another.  See the discussion for details.  Barring some late-breaking DNA study rescuing the current genera, a revision of the three genera, which nobody is looking forward to, may be required.