Hybridizing Petrocosmea - A Family Portrait

A Family Portraint showing P. rosettifolia #3 in the back, the seedpod parent of my first two hybrids...P. 'Keystone's Bantam, in the front, left and P. 'Rosemary Platz' on the front right.


With Petrocosmea season in full swing here in southwestern Pennsylvania, I'm enjoying an abundance of bloom. Yesterday I counted 58 Petrocosmeas in bloom, with almost as many still forming buds and yet to flower. But, no matter how many Pets I have in bloom, or how many are yet to come into my collection, two will always remain special in my heart...my first two hybrids. Petrocosmea 'Rosemary Platz' and P. 'Keystone's Bantam' are now currently in flower along with one of the parents P. rosettifolia #3. I had to take this occasion to take a photo of the three together for comparison.


P. 'Keystone's Bantam' with it's white flowers, each larger than it's leaves, and P. 'Rosemary Platz', which seemed to inherit all of the best features of both parents of the cross. I still have such a clear memory of the morning in October, 2007 when I made the cross, by applying pollen from P. sericea to the flowers of my favorite form of P. rosettifolia...the form I labeled #3. Within a couple of weeks, the seedpods were forming, and I remember thinking that they would probably contain no seeds, or if they did have seeds, they would not germinate. But, those three pods DID contain viable seeds and they were planted the following January, 2008. First flowers appeared in October and November of that same year. Through the whole process, I remained in disbelief that I had been able to finally produce seedlings after ten years of failed attempts.

Little 'Keystone's Bantam' was the oddity of the cross. It remained tiny from the very beginning. While it's siblings all grew quickly, it reached about 1.5 cm and stopped getting larger for months. Finally, that tiny green button of foliage did slowly get larger until it was 2 inches in diameter, when buds began to form. That original plant, shown above, remains under three inches today...more than three years later. This is it's third year of bloom. The tiny leaves are deep green, almost black at times, with the lighter yellow central veining of its P. rosettifolia parent. This was also the only white flowered seedling in the batch of more than thirty that I have flowered to date. The only 'tiny' one. I chose the name in honor of my dear friend and fellow Petrocosmea enthusiast, Paul Kroll. In addition to growing spectacular Petrocosmeas, as well as most other gesneriads, Paul grows, shows, and judges Japanese bantam chickens. The fantailed appearance of the flowers on 'Keystone's Bantam' reminded me of Paul's little chickens. Paul grows tiny little chickens, but his Petrocosmeas are gigantic.... I often say the Paul Kroll can grow a 12 inch Petrocosmea in a bottle cap! He phoned me this evening to tell me that his own plant of 'Keystone's Bantam' is now in bud also!!

The star of my first hybrid cross is indeed P. 'Rosemary Platz'...my very first named hybrid Petrocosmea. I named this hybrid in honor of another cherished friend - Rosemary Platz from Long Island, NY. Everytime I see this plant flower, I am reminded of how lovely my friend is. The flowers on this hybrid have a pleasant yellow throat with white and silver lavendar lobes on the corola. Flowers most resemble the P. sericea parent. Leaves are glossy, intermediate in shape and size between both parents, and with good culture, often show a subtle lighter veining. I have been very proud to see this hybrid showing up an winning some blue ribbons in shows when exhibited by other growers.

The Difference a Year Makes.... Petrocosmea cavaleriei

One of the interesting points I'm learning from the study of a single genus, day to day, for several years now is that Petrocosmea plants clearly evolve and change over time. One theory I'm starting to consider is that Petrocosmea may indeed progress through different "phases" or stages in development over time, as the plants mature. I've seen this with most of the species now. As young plants the leaves, flowers, pedicels or cymes, ...almost every characteristic of the plants, seem to change over time. Recently, I've been studying this, and have found a number of articles that discuss the molecular changes that the leaves of various plants go through as they mature.... I've begun to wonder whether this is truly what I am seeing with Petrocosmea, or if they are simply "growing up" and it takes more than a couple of years for them to mature.
I guess that is a topic for another post at another time...but the second annual flowering of a relatively new species to my Petrocosmea collection just makes me ponder my theory even more.

You may recall a post from October of last year, where I first introduced you to this species. While flowering is a bit later this year, the plant is putting on a spectacular, and more impressive show than it did last year. I also mentioned last year that I had begun sharing leaves of this species with a few friends. It has been fun, and rewarding, to get email and calls from those friends over the last few weeks, as the plants they propagated from those leaves are also flowering for them.



The photo above shows the same plant as the one in the photo below....it's just a year older now... Do you see a difference? Dramatic isn't it? The rosette really isn't much bigger with regard to diameter...but it does have more leaves. The plant remains in the same pot as it was a year ago when it first flowered. The plant now has a diameter of exactly four inches. Flowers are larger, and are dancing on the ends of purple pedicels. For such a small plant, it is making a dramatic show, and I am thrilled to have it in my collection. I've maintained three plants, and all three are nearly identical.

Just to refresh, my label reads : P. cavaleriei 'ABG 2005-2221' TT04. This label tells me that the plant came from the Atlanta Botanic Gardens, was collected in it's natural habitat in 2005. The 2221 is the ABG's accession number, and the TT04 is my own accession number, which ties to the records I keep of all of my Petrocosmea species. I make sure to pass these numbers along to anyone who I share leaves with. The species was collected in southwestern China.

The same plant flowering in the first photo, as it looked a year ago upon it's first bloom. Don't measure your Petrocosmeas by how they perform the first year or two after you get them...they must mature to show true potential. I am still amazed at some of my plants as they grow into the sixth, seventh, even the tenth year in my collection.. They impress me more each year.

An individual flower of P. cavaleriei shows that it fits easily into Petrocosmea Section Anisochilus. DNA studies show that it is very closely related to P. sericea and P. sp. 'HT-2'. I also detect a faint fragrance from the flowers of my plant, although not as much as I can smell from sericea or 'HT-2'. While sericea does not produce branched cymes for me, cavaleriei and sp. 'HT-2' do produce branched cymes with maturity. Like it's close relatives, this species likes to be grown a bit drier with regard to watering and drainage of the soil. It also seems to look best with a bit more light. Leaves, if kept too humid and splashed with water, will form the bleached spots often seen on African violets. P. sericea and sp. 'HT-2' also show leaf spotting, while I don't see this phenomenon on other Petrocosmea species.

An additional note regarding propagation... this species, as do other Pets with heavily felted leaves, will rot easily if the rooting medium is kept too wet during rooting. I avoid this by not burying the petioles, but simply laying them gently on top of the rooting medium such that the tip of the petioles just barely touch the medium. I've often had these species form plantlets when the leaves broke off and fell onto the acrylic matting I line my trays with.

I hope that with time, this species will get wider distribution among Petrocosmea enthusiasts, and that we will see it more often in plant shows. Since it does not have particularly ornamental foliage, however, it would likely do best in a show as a flowering specimen. Still, it is a fascinating new species to have in one's collection.

Fertile Forresttii Does It Again!

Little Petrocosmea forrestii is a mother again! While there are still some species that refuse to hybridize at all for me....like P. parryorum, and P. kerrii, and P. sp. 'China 2005', the species P. forrestii is taking up the slack for those species. So far, P. forrestii hybridizes more than any other species...having served as a mother in at least a half-dozen crosses for me. This year, I'm watching buds on P. forrestii crosses with sericea and minor.

The first of the forrestii x sericea seedlings flowered this week. I only got five seedlings from the cross. All five seedlings are showing buds. Foliage shows variation with some leaves narrow and cupped, like sericea and others showing rounded, flat leaves more like forrestii. All are quite small so far. I have them growing in two inch condiment cups, that have a capacity of two ounces...(I think.) Most are about the diameter of the cups...around two inches, with the largest, the first to flower...being about 2.5 inches in diameter. This seedling basically looks like a tiny P. sericea, with rounder leaves and very little of the cupping seen on sericea.


See the first flower to open below:


The first flower on P. forrestii x sericea..... can you see both parents in the flower? The flower is about the size of P. sericea, with a bit more of an upper lip to the corolla. A prominent white spot on the three lower lobes clearly comes from P. forrestii...although, sadly, none of forrestii's yellow came through. The dark purple blotch seen deep within the throat of P. sericea did come through in the progeny, and is just visible in this photo. Lower lobes are a bit more narrow and longer....more like forrestii.

The first seedling to flower from the cross looks much like a tiny P. sericea, although leaves are not as cupped as sericea.

This photo was a challenge....and my lack of photography skill didn't help anything. But, here is my best effort to show "MOM"...P. forrestii (left), "DAD", P. sericea, (right) and the seedling in the center. A side by side comparison shows the characteristics of both parents in the first flower.

I wonder, and wait, for the flowers on the other four seedlings. (P. forrestii x minor is just now showing buds peeking above the foliage.)

Petrocosmea 'Keystone's Bluejay'

"Just living is not enough - one must have sunshine, freedom, and a little flower". Hans Christian Andersen



I'm enjoying a beautiful day at home, with brilliant sunshine outside, and the beginning of Petrocosmea's peak bloom season inside. My spirits really got a boost this morning when I went down to my basement growing area to find the second flowering of one of my hybrids in full glory underneath the lights. The hybrid was one of the most challenging to produce. The only seedling that I kept from around tewnty that I grew from a cross between P. sericea and P. minor veined leaf form. I have named this hybrid Petrocosmea 'Keystone's Bluejay'.

P. 'Keystone's Bluejay' is one of my largest hybrids, and certainly one of the most challenging to create. P. minor had been particularly reluctant to hybridize. This cross was my first success with that species as a parent. The large blue flowers show an attractive ruffled texture, are significantly larger than either parent's flowers, and are distinctly fragrant. The scent is a spicy rose fragrance to my nose.

The plant is large, with rounded glossy leaves overlaid with a frosty silvery hair from P. sericea. The plant looks like a very large, frosted version of P. minor veined leaf form. The plant in all of its characteristics, is larger than either parent. The plant shown above is two and one half years old, growing in a five inch pan pot, with outer leaves 2.75" in diameter. The flower count is a nice surprise, since both parents can be shy bloomers with regard to flower count. The outer leaves are showing the yellowing of both age and neglect, which the plant suffered during this past summer. It tolerated the neglect well. Once flowering is complete, the plant will get some fresh soil and a little more tender loving care as a reward. Some dimensions on this plant are as follows: Total diameter of rosette is 11.75" (30 cm). Largest leaf diameter is 2.75 " (7 cm) and flower width is 1.25" (3 cm).

A close-up of a flower shows the ruffled texture of the flowers. The coloring in the photo is accurate and was taken in natural light.

This photo, from a previous blog post, shows P. 'Keystone's Bluejay' as a younger plant, when it won Second Best in Show and first place in New Hybrids' at the African Violet and Gesneriad Society of Western New York show last March in Buffalo, NY. I have been really happy with the performance of this hybrid. The extra effort was worth it!

Here they come!!!! The Year's Crop of New Hybrids Begin to Bud

"Take thy spade...it is thy pencil. Take thy seeds, thy plants...they are thy colors." William Mason


When it comes to artistic talents, as the quote above implies, I definitely have to rely on my little collection of plants to showcase my "creative" talents.... Assuming of course, that I have any talents. But, for reasons not fully understood, Petrocosmeas have finally decided to hybridize for me. After ten years of attempts and struggling to get even a single seedpod, or a single seed for that matter, the last few years have allowed me a bit of luck.

Last year, I harvested seeds from 14 different hybrid crosses. Of course, I don't have the space to grow them all, but I did plant a few, and the rest are stored in the freezer for another season. The cross which I am most excited about is shown below...P. forresttii x P. minor smooth leaf form.


The largest, and first, of eleven plants from the cross to make buds! P. forresttii x P. minor smooth leaf form was a cross that I made with the goal of getting the round, glossy leaves of P. minor on a small, neat plant like forresttii. So far, the plants look a lot like P. forresttii, but the leaves are rounder, and that lovely glossiness of P. minor is certainly showing up in varying degrees among the seedlings. A couple show very little of it...and look much more like P. forresttii...but the majority do show the clear influence of P. minor in the leaves. Some are staying quite small, others growing larger. The largest, pictured above, is now 4.25 inches in diameter.

While the seedlings are showing great promise of meeting my goals for the foliar characteristics hoped for in this cross, the final test with this, as with ALL of the P. forrestii crosses so far is.... "will the inflorescences, or pedicels, be short and strong, like P. minor (lets hope!!!) or will they be long, wiry and untidy...as with P. forrestii ( boo, hiss, hiss...) . P. forrestii, unfortunately, has proven to be dominant with regard to the thin, wiry, messy, tangled pedicels. While I do like the individual flower characteristics of P. forrestii's flowers, I am clearly NOT a fan of the habit of those pedicels it produces. One last concern for this cross will be the flower count. P. forrestii can be quite easily flowered, and quite floriferous, while P. minor often can be a bit shy to produce a heavy bloom count. Thankfully, both of these species very rarely produce suckers, so that standard goal of my hybridizing program will hopefully not be an issue with these youngsters. Still, one of the joys of hybridizing for me has been....that....one never knows what the combination of genes from two gesneriads will produce.

I'll keep you posted!

Petrocosmea parryorum....an update....

"A garden is never so good as it will be next year." Thomas Jefferson


The quote above, by one of my favorite American Founding Fathers, reminds me of my experience in studying the genus Petrocosmea for the past few years now. And, P. parryorum is a prime example.

I posted a couple of months ago, how my original specimen of P. parryorum, which has spent a decade with me now, is still teaching me lessons and revealing its secrets with each new season. This year, it bloomed twice...once in January and again, starting what has been a very long and productive season of bloom in August. It continues to flower its last few remaining buds, three months later. That means that to date, this glorious species has been in flower for me nearly one half of the year! And, it is still going!

Pictured above, the now quite ragged and tired plant is still supporting the last few buds, remaining on the final 11 inflorescences. Here's the progress report so far.... it began with a rosette of leaves that was well over 14 inches in diameter when the first buds opened. Now, it has dropped the outer ring of leaves...likely due to the redirecting of energy into the flowers. It has produced 14 inflorescences, with as many as 57 buds on each inflorescence!!! Yes, that's correct...I removed one, pictured below, so that I could count the buds and also to preserve it in my private little "Petrocosmea herbarium" where I press and dry the various structures of each species Petrocosmea in my collection. SO, at around 50 buds each...I estimate that this plant has now produced around 500 flowers in one flowering season!!!! I've been amazed at this plant!

A dried Petrocosmea parryorum inflorescence. Some of the buds in this photo are underneath other buds, and a couple accidentally broke off, as can be seen on the left of the photo...but this one, and one other that I removed, each sported over 50 buds...the one above had 57, the other 54. I would surely love to get this influence incorporated into some Petrocosmea hybrids, but alas, I have not yet found a single flower on the plant that had pollen!! Attemps to pollinate it's flowers with other Petrocosmeas has resulted in no success. I have to wonder if the fact that it flowered during the late summer, when we were quite warm, might have affected the pollen production. I've consistently had better pollen production and better success with hybridizing in the middle of winter when temperatures were quite cold.... The flowering of this plant last January did produce pollen in the flowers.

A close up of a few of the current inflorescences on the plant above...showing a mix of spent flowers, open flowers, and a last few remaining buds.

I wonder what next year will reveal about P. parryorum...the Petrocosmea from India.

Autumn, and Petrocosmea season begins!

"My green thumb came only as a result of the mistakes I made while learning to see things from the plants' point of view" H. Fred Ale



Petrocosmea flaccida 'ABG 1998-5551' a new clone of this old, dependable species.




Petrocosmea season always really gears up into full swing for me in the autumn. Those cool, damp nights make the cool-loving Petrocosmeas very happy. It always amazes me that even though they are growing indoors, under lights on timers, and all of this is done independent of the weather outdoors, the plants always "know"...they know what the climate outdoors is doing.

This year, I'm especially enjoying a darling little plant that I acquired about three years ago as a gift from a friend at the Atlanta Botanic Garden in Atlanta, Georgia.... A new collection of Petrocosmea flaccida. This clone was collected in 1998. I was delighted to get some "new blood" in the form of a new collection of Petrocosmea flaccida. I am growing, and have distributed this plant under the clonal designation 'ABG 1998-5551', which is the ABG's accession number.

I first wrote about this clone on this blog last year, when it flowered for me for the first time. Now, with another year of maturity, I've had the chance to watch how it performs when grown under identical conditions to my original P. flaccida, which I've had for years. I find this clone superior for a couple of reasons. First, it does not sucker nearly as much as the original clone. Those of you who follow my blog know how I dislike this pesky trait of some Pet species...so finding a clone which has less of a tendency to sucker is a positive characteristic in my opinion. Secondly, it shapes nicely and remains quite small....about half the size of it's larger sister, my original clone of P. flaccida. Leaves are quite small...more like the size of P. forrestii leaves. I would love to hybidize with this clone to see if it contributes to smaller Pet hybrids. I've tried several times to cross it with the original P. flaccida and to self it...without success. I think this may be due to the fact that both forms bloom early in the season...when it is still pretty warm...and I have much greater success with setting seedpods with the temperatures are much colder.

An overhead shot of P. flaccida 'ABG 1998-5551' shows what a lovely habit this form has. I have not trained it or removed suckers...and this is what it has done in it's second year of bloom from leaf cuttings. The diameter of the plant shown above is just under 4 inches diameter. This plant is potted in a three ounce shallow condiment cup where it has now remained for two years.