The following table shows the primary hybrids (species x species) between those species in the Corytholoma clade most frequently used in hybridizing. This is not a complete list, but it should provide some guidance about what things have already been done. Notes for each species provide additional information about secondary crosses and other potentially useful information.
There is a lot more empty space in this table than in the corresponding Dircaea table, which means that there is a lot more opportunity for hybridizers. While the plants of this clade are not in general as showy, especially in regard to flower size and foliage, there are some new species like S. araneosa and S. nordestina, plus S. bragae, which should offer good material for crosses. Both S. aghensis and S. bragae should be crossed with the micro species, since the molecular data indicate that the micros are closely related to S. aghensis and possibly to S. bragae as well.
Prospects are not so bright for getting anything good from S. richii. It is way out on the very edge of the clade (see the table), so at best any cross would be sterile. The same may well be true of S. barbata.
That being said, it should be mentioned that tetraploidy provides opportunities that strict genetics would seem to preclude.
Crosses between the aghensis/miniatures group and other species in the clade or in the Dircaea clade have proved to be sterile, but fertile tetraploids of those hybrids have appeared in a number of cases. Such tetraploidy may be available in the case of other Corytholoma-clade hybrids too.
In the Dircaea clade, it is quite likely that all primary crosses -- in fact, all crosses whatsoever -- will be fertile. The species in that clade all seem quite closely related. Crosses involving the species most distantly related to the rest (namely S. reitzii) have all been fertile, in my experience, so there is little reason to expect any such crosses to be sterile.
Things are different in the Corytholoma clade, which includes some species (most notably S. richii) that are only distantly related to the rest. Nonetheless, crossing experiments over the years have yielded some good results. What appears to be the case is that hybrids among the species in the Corytholoma core group are at least somewhat fertile. Hybrids in the aghensis+miniature group are or may be weakly fertile. Outside of those clusters, it is unlikely that crosses will be fertile.
Some three-species crosses have been done in the Corytholoma core group. See the S. 'Apricot Bouquet' page for an example.
In the 1960s, Carl Clayberg did a set of crossing experiments between species of Sinningia (and Rechsteineria). He included four members of the Corytholoma clade: S. aggregata, S. tubiflora, S. warmingii, and S. incarnata. For the complete results, see the crossing chart. For our purposes here, it suffices to note that he showed that all six possible combinations (considering A x B and B x A to be the same) produced fertile hybrid plants.
Key to the table:
|06||one of the Clayberg 6 (fertile hybrid)|
|X||hybrid of unknown fertility|
|w||weak plant that did not bloom|
As we did on the early-crossing page, we can rearrange the order of species in the table to group species which form fertile hybrids with one another.
The result is not as dramatic, but we can still see the block of about 60% of the species (down through S. nordestina) that constitute the Corytholoma core group, plus a smaller block in the lower right corner containing the aghensis/miniature group.
Sinningia aggregata [yellow-flowered form] x amambayensis was created by Dave Zaitlin. See Dave's picture to the right. This hybrid should be fertile.
Sinningia aggregata x brasiliensis yielded a fertile hybrid according to Wiehler and Chautems.
Sinningia aggregata x concinna yielded a sterile hybrid in Clayberg's experiments. This is the hybrid Sinningia 'Tinkerbells', known for its small size but sprawling habit.
Sinningia aggregata x incarnata yielded a fertile hybrid in Clayberg's experiments.
Sinningia aggregata x richii yielded a sterile hybrid in Clayberg's experiments.
Sinningia aggregata x sellovii was done by Leong Tuck Lock of Malaysia, who reports that he has selfed some of the flowers. See a picture.
Sinningia aggregata x sulcata: Ruth Coulson had a plant of this hybrid in the 1980s, and reports that it is/was fertile. The two-tone yellow/pink flower sounds similar to the amambayensis x sulcata flower mentioned below. John Boggan, on Gesneriphiles, wrote that S. aggregata and S. sulcata were among the ancestors of the hybrid S. 'Krezdorn Yellow'.
Sinningia aggregata x tubiflora yielded a fertile hybrid in Clayberg's experiments.
Sinningia aggregata x warmingii yielded a fertile hybrid in Clayberg's experiments.
Sinningia aghensis x brasiliensis yielded a hybrid of unknown fertility according to Wiehler and Chautems.
Sinningia aghensis x bragae: Dave Zaitlin made this cross, and he and I sowed the seed and got seedlings. However, they remained small and eventually did not come out of dormancy. This is may be evidence that the two species are not as closely related as they appear to be.
Sinningia amambayensis x nordestina was created by Alan LaVergne. The hybrid is fertile, and F2 seedlings have been obtained. See the discussion on the S. amambayensis page.
Sinningia amambayensis x sulcata was created by Alan LaVergne with pollen from Jon Dixon's S. sulcata and has bloomed. It is unclear at this time [October 2008] whether the hybrid is fertile. See the discussion on the S. amambayensis page.
Sinningia nordestina x araneosa was created by Alan LaVergne. This hybrid has its own page.
Jon Lindstrom has done the cross Sinningia araneosa x tubiflora and reports that it is fertile. It now has its own page.
Sinningia barbata x warmingii yielded a weak plant which never bloomed in Clayberg's experiments.
Sinningia brasiliensis x incarnata yielded a fertile hybrid according to Wiehler and Chautems.
Sinningia brasiliensis x warmingii yielded a fertile hybrid according to Wiehler and Chautems.
Sinningia concinna x pusilla was apparently created more than once in the 1960s. Carl Clayberg crossed it with Sinningia pusilla to get Sinningia'Bright Eyes' in 1964, and Lyndon Lyon registered the primary hybrid as Sinningia 'Wood Nymph' in 1966. See also the miniatures page. According to Peter Shalit, "the F1 ('Wood Nymph') is only weakly fertile and cannot be selfed. Carl Clayberg got seed by applying pollen from Sinningia pusilla and ultimately bred Sinningia 'Bright Eyes'. But I would call the original species cross weakly fertile."
Sinningia concinna x muscicola was created by Jim Steuerlein, and given the name "Li'l Georgie". He reports that the F1 is fertile and that he has blooming plants of the F2 generation.
Sinningia concinna x sellovii was created by Dave Zaitlin, and given the name "Deep Purple Dreaming". See its page.
Sinningia incarnata x richii yielded a sterile hybrid in Clayberg's experiments.
Sinningia incarnata x tubiflora yielded a fertile hybrid in Clayberg's experiments. Ruth Coulson reports that she has this hybrid (labelled as tubiflora x incarnata) and that it has pink flowers of the tubiflora shape, but unscented.
Sinningia incarnata x warmingii yielded a fertile hybrid in Clayberg's experiments.
Wu Jui-Jung of Taiwan did the cross Sinningia pusilla 'White Sprite' x aghensis. For a picture and some description, see this page. Since Mr. Wu has back-crossed this hybrid to S. pusilla, we can infer that it is fertile.
Keith Hussen of Canada did the cross Sinningia pusilla 'White Sprite' x muscicola.
Jon Lindstrom did Sinningia pusilla 'White Sprite' x bragae, and has crossed it with S. insularis and S. pusilla, so it is obviously fertile. He has named this plant Sinningia 'Arkansas Royalty'.
Vincent Parsons did Sinningia muscicola x bragae in 2007, and the resulting plant had flowerbuds in January 2009.
Sinningia pusilla x helioana was created by Dale Martens, using pollen from Karyn Cichocki, and named 'Heartland's Flashlight'.
John Beaulieu did the cross Sinningia nordestina x sellovii and got flowers -- as far as I know, the first S. nordestina hybrid to bloom.
Sinningia richii x warmingii yielded a sterile hybrid in Clayberg's experiments.
The cross Sinningia sellovii x sulcata: Ruth Coulson had this and reports that its flowers were pink with yellow lobes; the latter trait appears to be characteristic of S. sulcata hybrids.
The cross Sinningia sellovii x tubiflora has been done by Dave Zaitlin. It is fertile.
It was also done by Jon Lindstrom. According to its publication in the 2011 Q2 issue of Gesneriads, he made the cross in May 2003 and it flowered in May 2004. A picture shows a shrubby plant with numerous pendant pink flowers. Jon named it S. 'Arkansas Bells'.
S. sellovii x tubiflora goes back a long way. Seed from this cross was offered in the (defunct) American Gesneria Society's seed fund listing in 1971 (in Gesneriad Saintpaulia News).
Jon Lindstrom crossed it with S. guttata. Since the latter is in the Sinningia clade, the hybrid should be sterile.
Sinningia tubiflora x warmingii yielded a fertile hybrid in Clayberg's experiments. This plant may or may not still be around. A plant with the same two parents is in circulation under the name Sinningia 'Carolyn', named after Carolyn Ripps of the Gesneriad Society's seed fund.
Bruce Dunn, Jon Lindstrom's graduate student at University of Arkansas, has crossed S. piresiana (Dircaea clade) with S. aggregata.
Sinningia amambayensis hybrids have so far looked much like S. amambayensis. However, because of the central position of this species in the clade, the hybrids may well be fertile and thus provide opportunities for further development.
Sinningia bragae: Bill Price crossed this with S. eumorpha 'Saltão'. Jon Lindstrom crossed this with S. conspicua, and with his hybrid S. araneosa x tubiflora.
Sinningia barbata: Frances Batcheller crossed this species with her hybrid S. 'Ramadeva' to get S. 'Benten'.
Sinningia pusilla has been crossed with a number of species outside the clade. John Boggan reports that one of his earliest crosses was S. pusilla 'White Sprite' x schiffneri to create S. 'Paper Moon'. He says that Frances Batcheller had done virtually the same cross a few years earlier (using the standard form of S. pusilla), but didn't name it.
In this picture can be seen the schiffneri-like markings in the throat of the corolla, which is white with just a tinge of lavender. Corolla shape and size are roughly the same as both parents.
Sinningia muscicola, which has similarities to S. pusilla, has been used in several hybridization projects. Jim Steuerlein crossed it with S. conspicua and S. bullata. The conspicua cross has its own page.
Jon Dixon created at least one S. sulcata hybrid several years ago.
Sinningia sellovii has been crossed with many species, including S. elatior.
Ruth Coulson did the cross S. warmingii x carangolensis.
Answer to your first question: they were both in bloom.
Sinningia richii: Frances Batcheller crossed this species with her hybrid S. 'Ramadeva' to get S. 'Kore'.