Petrocosmea Hybridizing - Harvesting Seeds

Having tried to successfully pollinate Petrocosmea flowers hundreds of times over a period of tens years, it is difficult to describe the joy of being able to say "I'm harvesting Petrocosmea seeds today!" This is my third annual seed harvest and the crosses this year have me excited about the potential for attractive, new foliage and flower characteristics...and maybe even some new colors or at least new "shades" of color. This season, so far, if my counts are accurate, I've applied pollen to 323 flowers. I've collected 21 seedpods so far, all with seeds inside, although some had a precious few seeds. I accuse me of being a bit of a fanatic about Petrocosmeas, I guess. But it is harmless fun and very exciting. I'm learning so much about this genus.

So what am I learning? Here are some observations about hybridizing Petrocosmeas and successful seed set. First, I must say again, that for me, the two key factors in my success, I believe, are making the crosses and allowing the flowers and seedpods to develop in cool temperatures (cold by some definitions) and high humidity....(100% if I can get it). Most of the failures this year, also served to prove this point for me. The early bloom season this year began in summer, when we were quite warm. The plant room was in the mid-70's F. The plants were growing out in the open shelves with the humidity at about 60%. All of those attempts failed. I did get seedpods to form on some P. begoniifolia flowers that were covered, but again they were growing in warm temperatures. All of those seedpods were empty when they ripened. As the plants continued to flower, and the temperatures began to drop with the arrival of autumn, I did not begin to have success until November 29, when I made several crosses in temperatures in the 40's F and most all took! These plants were all enclosed inside my humidity domes, so humidity was 100%. Since then, with the cool temps, I've had nearly 90% success with all species EXCEPT the P. minors...which still refuse to be seedpod parents. I have limited success with this species as a pollen parent and got one more cross this year with P. minor veined leaf form as a pollen parent onto the species P. rosettifolia #3. That was it. Excluding this species, I'm now having excellent results with high success rates if I observe the rules above.

In the photos above and below, you see the seedpod of Petrocosmea rosettifolia #3, which I feel in many ways, is the showiest of all of the forms of this species. The seedpod ripened in 62 days and was FULL of seeds, which can be seen in the second photo below. The seeds are large and plump, so I'm hoping they germinate! This exciting cross using P. rosettifolia as the seedpod parent and P. minor veined leaf form as the pollen parent, was made in the hopes of getting the darker green, and bright yellow veining of the leaves of P. rosettifolia #3 crossed onto the highly glossy, deeply veined leaves of P. minor veined leaf form. Also, I'm hoping that the purple flowers of minor will get some of the deep yellow in the throat of P. rosettifolia #3. I'm also hoping the ease with which P. rosettifolia #3 accepts pollen and sets seed will come through in fertile progeny to be used for further breeding. Who knows what I'll get, but then, therein lies the fun of hybridizing!

A bountiful seed harvest from P. rosettifolia #3. Other forms of this species are reluctant to hybridize or self. This form is almost always successful as a both a pod and pollen parent. Note that the seedpod splits along opposite sides from tip to base.

The large, showy, snow white petals of P. rosettifolia #3 surround a bright lemon yellow throat. Happily, it is a great parent. Flowers on this form are the largest of any form of P. rosettifolia.

The mother plant of the seedpods shown above. This photo was taken on the day that I began to make crosses with the plant. I'm hoping that the deep green, yellow veined, and glossy leaves come through in the hybrids. This form also is reluctant to form offsets, whereas other forms of the species form them quite readily. Flowers are large and showy, and present in an attractive fashion over the well-shaped crown of leaves....In many ways, a perfect parent for hybridizing.

The pollen parent of the cross which produced the seedpods above. This is the flower of P. minor veined leaf form..... a fragrant flower! This species has consistently been reluctant to serve as a pod or pollen parent with other Petrocosmeas, or it's siblings, or when selfed. It just doesnt' want to cross. Likely, the problem is that I have not yet discovered some peculiarity about it's fertility. You can bet that I'll keep trying. It has been successful as a pollen parent only twice before....crossed onto P. sericea, P. forrestii, and now P. rosettifolia #3. I'm hoping that the latest cross will infuse some yellow into the clean white throat of this flower for some tricolored flowers in the next generation. If it passes the fragrance along, I'll be happy with that too!!

Other things I've learned..... Petrocosmea crosses seem to take a minimum of 60 days for seedpods to ripen. A couple of crosses have taken up to 80 days to ripen. The two top species for successful crosses have been the prolific little P. forresttii in the number one spot, and P. rosettifolia #3 in the number two spot. P. sericea and sp. 'HT-2' would be in the number three spot. All of these have been successful in most all of my attempts to use them as parents. This year, I tried P. parryorum, which bloomed for me with lots of flowers. Not one attempt was successful, and I tried! Believe me I did~~!!! Attempts to use P. parryorum as either pod or pollen parent were all unsuccessful. The pollen was often rotted. I'm wondering now, if perhaps this species does not like the high humidity to pollinate? I'll be trying again next year with plant in both the uncovered and covered areas to see if by lowering humidity I preserve the pollen and maybe have some success? P. kerrii was also unsuccessful, in all but one attempt. Again, little P. forrestii came through for me and produced two tiny seedpods with a few seeds....Now if they will only germinate. P. begoniifolia seems to be the most flamboyant species for producing full, round flowers, with nice ruffling and coloration on the petals. I've used it in several crosses this season in hopes of some breakthroughs in the flowers.

One last observation that I'll mention about hybridizing. Use flowers that have been open for at least four days. It seems to take that long for the pistil to enlongate and the stigma to be mature and receptive. I've gotten to the point that I can tell by looking at the stigma when it is mature. Use pollen from freshly opened flowers, as it seems to lose viability quickly in the high humidity. But, it loses viability much quicker in the low humidity...high humidity rots it, low humidity dehydrates it. I tried storing it in the refrigerator and the freezer...so far, no success using stored pollen.

SO, a fun day, harvesting seeds and getting filled with the anticipation of the new Petrocosmeas to come along as these seeds begin to grow and show their stuff! Stay tuned.......

And you MUST try hybridizing!

Winter's Wonders

Winter is a beautiful time of year here in southwestern Pennsylvania. The icy scene outside the window of my upstairs sunroom from a couple of weeks ago as we were under the effects of one of the coldest periods in the area since the 1700's is a testment to the wonders of nature. (The largest of those icycles are over 5 feet long!) While the temperatures dipped outside, I have been using the time to work with my gesneriads inside. It was a great excuse to stay indoors and enjoy those other wonders of nature - Petrocosmeas!

I decided to post some random comments about what was going on in the plantroom. While we are squarely in the middle of winter here, I am seeing the final days of the flowering season for the Petrocosmeas. This has been an atypical season for flowering this year. Usually, the Pets begin flowering for me in October and conclude around March. This year, they began flowering in early August! P. barbata, as usual, was the first to flower, and P. duclouxii and P. sp. 'Yumebutai' are rounding out the season as the last to flower...again, it is typical that these are the last, but they are much earlier than normal. We had a cooler and wetter summer, much cooler and wetter, last year, so I feel that the lower temperatures during the summer triggered an earlier season for the Pets.

The last of the seedlings from the P. 'Asa Blue' x begoniifolia cross are now blooming. The one above I had pulled out of the batch and named P. 'Keystone's Whipporwill'. It produces a large flower, with wide petals, giving the flower a nice, full appearance. The petals have a ruffling and notching that I find different and pleasing. This photo actually shows the color accurately, but the focus is poor...I apologize. The photos with better focus had the coloration all wrong. Many of the flowers show extra petals too, as does this one. I am evaluating it another year or so, and will perhaps release it if it meets my two main criteria....heavy flower production, and a reluctance to form offsets. So far, it looks quite promising. The negative is it's long peduncles, from the 'Asa Blue' parent. It was grown in low light this year, so I hope that with better light, they will be shorter and heavier. They did always support the large flowers, so that is good, but I just wish they were a bit shorter for a neater presentation of the plant as a whole when in flower. We'll see what another year of growth and another flowering season does for the plant.

Another species that tends to bloom later in the season for me is P. forrestii, seen above. This species has, for two years now, been the easiest species to use as a seed pod parent. So, if you want to try your hand a hybridizing...start with this species! So far, only two attempts to use it as a seedpod parent have failed. It has worked with species that would not cross with anything else. It's a prolific little species! It's positive qualities for hybridizing are it's neat, compact, perfectly symmetrical leaf habit. It forms a perfect, round, flat rosette. It is also very floriferous, over a long season, and flowers at a young age...all good traits for hybridizing. It's primary negative trait is the long, weak, wiry peduncles. They tend to get long and often form a tangled mess when the plant is in heavy flower. It has been recessive for the flower shape and the yellow blotch on the lower petals...neither of these qualities have shown up in a single seedling! It is dominant for the leaf shape, and the perfect symmetry of the rosette. Thankfully, those long, weak peduncles are about 50/50 in the progeny.

Finally, I thought I would throw in a couple of photos the "other" gesneriads! I actually DO grow gesneriads other than Petrocosmea! I have quite a large collection of other species from various other genera within the family. A couple of nice, uncommon species are in flower now.

Columnea raymondii is showing it's very first open flowers for me. This species is fairly new to my collection. I have always been a fan of the upright Columneas. This one came into my collection as a small cutting last July. It has been growing nicely on the windowsill of the upstairs sunroom, where it gets both eastern and southern exposure. I wish you could see these flowers! They are dramatic, striking, and very large...at least they seem large to me. The flower above is about four inches from base to tip. The petals are a deep, glossy bright maroon/red color with a very heavy substance. The outside of the petals and the tube are greenish yellow. The flowers are underneath the large green red-veined leaves. If you can find this one, you MUST try it!

And last, but certainly not least....a coveted plant for me. I've been trying to find a source for the species Smithiantha aurantiaca for more than ten years...with no luck. When I mentioned this to a friend last spring, she promised to bring a plant to me at the Gesneriad Society Convention in the past July. The first thing I did was to remove a leaf and put it down to propagate. From that leaf I got three more plants. Now, I had insurance! The original plant went into a four inch pot under the lights on the light bench, and was wicked into a reservior of dilute fertilizer water and never allowed to dry out. It grew quickly into a large plant with bronze leaves covered in rusty red hairs. A couple of months ago, the first buds began to appear on a tall, upright central spike. The coloring of the flowers is nearly impossible to capture, but it is intense. This plant is the first thing my eye goes to everytime I enter the room. The blooms seem to be illuminated from within...a bright, cheerful orange color with red spots inside the throat. I'm so happy to have this rare beauty in my collection. I've been attempting to self pollinate the flower, with no success so far...perhaps that explains it's rarity. I'm hoping that it produces lots of scaly rhizomes, but as I said, I am also having good luck propagating it from leaf cuttings. Again, a must have if you ever have the chance to grow it.

So, even with the cold, crystalline, wintery world outside, my home is bright, colorful and filled with it's own versions of the "wonders of winter". I hope that yours is too!

Good growing!!!!!

A New Year and New Discoveries

First, I have to say Thank You! to all of those who have read my blog this year! I cannot express how much I appreciate the comments I've received about it from many of you. It was a bit of a self-indulgence on my part, but I hoped that it would find an audience among others who loved Petrocosmea as I do, and that it might be helpful for those who are learning about them and wish to know them and grow them better...as I do. Today, after only four months the blog has had over 900 visitors from 34 countries. I am amazed!! It has been a lot of fun to put together and I will forever be appreciative to all of you for reading it. I hope that 2010 is a wonderful year for all of you!

The new year is bringing still more new discoveries for me about Petrocosmea. First, the one species which I have found the greatest challenge to flower, finally is beginning to flower! What a great way to start a new year and a new chapter of exploring the wonders of the genus Petrocosmea! Petrocosmea sp. 'Yumebutai' came into my collection as a gift from a great friend and expert Petrocosmea grower, Paul Kroll of East Aurora, NY. This plant was first grown by a grower for the Yumebutai Nursery in Japan and was given to an accomplished gesneriad grower, Mr. Toshijiro Okuto. Mr. Okuto then gave the leaves to growers here in the USA and one of them was Paul. The plant appears as a large form of one of the Petrocosmea rosettifolia group, and initial DNA studies are showing that it is a close relative to that group. Leaves are quite thick and have a heavy substance. They are deep forrest green, with a lighter center. The hair on the leaves is bristle-like and stiff, giving the leaves a very rough texture. The leaves, for me, have not gloss to them, the have a dull appearance. Leaves tend to cup downward.

As I said, it has been a reluctant bloomer. Blooms are quite unique....the resemble those of the rosettifolias, but have only four petals as opposed to the usual five. Flowers are purple, with a creamy white throat. The two upper petals form the typical short hood of members of the Section - Anisochilus. Peduncles are purple, with up to five buds each. It is forming lots of buds, so it appears it will be floriferous. Mr. Okuto's photo of a plant in bloom does show a heavily-flowered plant, however, I cannot see the flowers well enough to determine petal count. I have not used it in hybridizing.....YET!


Petrocosmea sp. 'Yumebutai' finally flowers. Bud and bloom count appears to be high. Flowers have only four petals, making them appear elongated.





Another surprise came this morning, very early, as I went down to the plant room in my basement to check on the Pets. I have been growing two plants of P. minor veined leaf form under humidity domes, in preparation for using them for hybridizing. This morning, as I lifted the dome from the tray, a spicy floral fragrance wafted up from the tray! WHAT? A fragrant Petrocosmea?!? Sure enough, several more "sniffs" of the flowers confirmed that they were indeed quite fragrant. I then began to smell other Petrocosmea in bloom. I also detected a similar, although fainter fragrance on P. sericea. A seedling from a cross between P. sericea x P. minor veined leaf form also has a mild fragrance. Admittedly, I have never checked for fragrance on the flowers of Petrocosmea, so had not noted it before. I will be checking more Pet flowers in the future. If you have these species in flower now, you must check them for fragrance. I suspect that the fragrance was intensified by the humidity dome covering the tray, but I could still detect it later in the day after the tray had been uncovered for a while. A new discovery!

Petrocosmea minor veined leaf form....the flowers of this species have a spicy floral fragrance...at least to my nose. If you have this species...give it a sniff!

Last evening, as I was examining some dissected Petrocosmea flowers under a microscope, I noted that the flowers of P. rosettifolia #3 had four stamens. Most Petrocosmea flowers have two stamens and two staminodes...or no staminodes. This species clearly had four. I checked the flowers of P. rosettifolia #1 and #4 and they two had three or four anthers each. I then went back to double check flowers of several other species...begoniifolia, flaccida, duclouxii, minor, sericea...all of these species have two stamens. What does this mean? I don't know. But it found it interesting. The stamens of rosettifolia constrict to form a "beak" as the anthers are all attached to each other. This is a trait of the species in Section - Anisochilus.

I have sketched the flattened flower of P. rosettifolia #3 below to show the arrangement of the four anthers...pardon my rather crude artistic skills.

A quick sketch of the flowers of P. rosettifolia #3 shows the four stamens encircling the base of the ovary and pistil. The filaments on this species are often crooked with an "elbow" at the midpoint of the filament. The filaments of most other Petrocosmea species are straight.


Last, I would like to honor and pay tribute to a dear friend to all who love gesneriads.....Frances Batcheller. Sadly, in November , 2009, we lost Frances at the age of 96. I was honored to have met and become friends with Frances in 2000 when I attended my first Gesneriad Society (then the AGGS) convention in Tampa, Florida. I had read articles by Frances Batcheller for years. She was a self-taught botanist, and form many years, was THE expert on them. Frances was also an active and accomplished hybridizer of gesneriads and established the judging program for the Gesneriad Society. She was the first Judges Chairman of the Society and many judges remember judging with Frances and learning from her. I was so excited to finally get to meet Frances face to face. We became friends and exchanged letters by mail for several years after that. She always treated me as if she'd known me for years.

Frances Batcheller, in earlier years.

Touring the showroom of the 2000 AGGS convention with Frances Batcheller. I tried to absorb everything Frances said...when Frances spoke, everyone listened!!!!

While at my first Gesneriad Society convention, I won the coveted "Tour of the Showroom with Frances Batcheller" ....an traditional item in the live auction. I wasn't going to pass up the opportunity to "learn from the Master". I still recall trying to absorb every word Frances said about every plant she discussed as we toured the showroom. Frances had a knack for summing up the key points about any exhibit in the gesneriad show with a few, well-chosen words. She had a great sense of humor and was such a wealth of knowledge about every plant. The thing I admired about Frances was that on the rare occasion when she encountered a gesneriad that she did not know, she would turn and immediately admit that it was a new plant to her and she would begin to ask questions about it from anyone who she thought might know the plant. She was always eager to learn more about gesneriads. She always said that a good judge should not fault the exhibitor for the judge's ignorance about a plant.

As Frances' health began to fail in the last few years, a convention never felt the same without her. Frances taught me that I should always strive to learn everything I could about the gesneriads I love. I think of her often as I work with and study my gesneriads. Rest in Peace, Frances.

Angora and a Little Rascal

With the flowering of each new cross, I get more and more excited about the potential for hybridizing within the genus Petrocosmea! I often think back to what it must have felt like for those very first hybridizers of African violets and then reflect upon the myriad of flower and foliage variations available today within that genus. Looking at a collection of species Saintpaulia, one might never imagine the variety that would have evolved from those charming, but fairly simple and uniform flowers and foliage types among the species in that genus. Oh, the things that are yet to be within the world of Petrocosmea!!!!! ( I can dream, can't I???)

The subject of my current adoration is the offspring from a cross between P. forrestii (as the seed parent) and the magnificent, and quite unique P. duclouxii. Both very different from each other in a number of ways. I was on Cloud Nine when I saw those seedpods developing! Now, ten months later, the babies have grown up and are showing first flowers. I've selected two from among the twenty that I flowered to name,and one other one which is remaining unnamed for the moment. P. duclouxii was clearly dominant form flower type in every seedling. P. forrestii was dominant for foliage type among all but one of the seedlings. Flower size was a mixed bag, with about nine having smaller flowers like forrestii and 11 having larger flowers like duclouxii. Peduncle length was clearly influenced more by forrestii...which I was not so happy about. Now, here are the "kids"........


Petrocosmea 'Keystone's Angora' was the first selected and named. It was chosen for it's magnificent foliage, which appears as a large P. forrestii, but the leaf texture is outstanding. I wish you could touch the screen and feel these leaves! They are literally as soft as angora! I HAVE to pet them everytime I see this plant. Hence, the name! The plant is showing more buds to come. I'm hoping for a bit more bloom with maturity, since both parents are quite floriferous.

The flower of P. 'Keystone's Angora' ...a smaller version of it's P. duclouxii parent, but a bit pinker, due to the influence of forrestii. Petals are rounder and more obtuse on the tip, making the flower less "starry" than those of P. duclouxii. Anthers are deformed, producing no pollen, but the pistil appears normal. I'm hoping it will be seed-fertile.

The second seedling names is P. 'Keystone's Little Rascal'. Leaves are more like duclouxii in shape and texture, with some veining, but size of the foliage is more like forrestii. It was chosen for it's heavy flower count and small size. It was the only seedling to inherit the shorter, sturdier peduncles of P. duclouxii. All other seedlings have the long, unruly peduncles of P. forrestii...and undesirable trait in my opinion. This plant did form two offsets, which I was not happy about, however, it's positive qualities of heavy bloom count, peloric flowers, most with extra petals, and the sturdier peduncles won out. The flowers on this plant are quite small, among the smallest of all it's siblings. I'm happy with it's reduced size and compact habit.

Most of the flowers (92% of them) were near-peloric and had extra petals. Again, as with all of the flowers in this cross, the anthers are deformed and produced no pollen. Pistils appear normal.

One other trait from this cross which I was very happy about, was that it produced three very small, almost "miniature" seedlings. This is the third Petrocosmea cross, involving larger parents that has show a tendency to produce a few "miniatures". My first cross, P. rosettifolia #3 x sericea produced one miniature plant, which pure white flowers (P. 'Keystone's Bantam'). By using P. 'Kesytone's Bantam' in a cross with P. forrestii (the most compact of the species), I got 100 miniature seedlings...all MUCH smaller then 'Keystone's Bantam'. None of these have flowered yet, after 11 months, and most all are producing HEAVY offsets, a trait which I am attempting to select out of the hybrids that I release, so I am not sure that I will ever release any of these. These miniatures do, however, give great hope to me that miniature Petrocosmeas are a real possibility and likely not too far in the future. Just one more exciting and mysterious trait tucked away within the genetics of this genus.

A photo showing the difference in the size of the flowers of P. 'Keystone's Little Rascal' (on the right) and one of it's siblings....(which I have not named so far). Both of these are smaller than the parent P. duclouxii. Petal shape, petal width and length all were quite variable, as can also be seen in the photo The petals of the larger flower on the left are more oblong and narrow, giving the flower a more "star-like" appearance. The petals on 'KLR' on the right are shorter and more ovoid in shape, making the flower appear rounder and fuller.

And, as must be done, the remaining 17 seedlings all went into the trash bin...... Rest In Peace!

A "Child" Grows Up... Petrocosmea 'Rosemary Platz'

In a recent post, I promised that I would post a photo of my first named hybrid P. 'Rosemary Platz' as it came into full bloom this season. This was the hybrid that heralded the beginning of what has been an incredibly rewarding, enjoyable, and educational experience for me. It happened by accident, really.

A couple of years ago, after having tried for nearly ten years to get Petrocosmeas to set seed, I made yet another attempt. Due to impending long days and heavy weeks ahead with my shifts at work, I had placed several of my Petrocosmeas that were showing buds underneath a humidity dome in my basement light stands. In early October, two species were sitting side by side underneath one of those domes, and both were in flower. P. rosettifolia #3 and P. sericea. So, on a whim, I took the pollen from both flowers and made reciprocal crosses between the two species. I then put it out of my mind, assuming, as had always been the case, that both would fail. A month or so later, when I had a chance to check on my plants in between shifts, I noticed seedpods forming on both species!!! WHAT?!! It couldn't be! But, yes, there they were...five seedpods... three on the rosettifolia and two on the sericea! I don't recall how many flowers on each species I had pollinated, but some had indeed worked. Sixty-seven days later, I harvested the seedpods from P. rosettifolia, and then about two weeks after that, the seedpods on P. sericea were harvested. There were seeds inside of all of them.

Eight months after sowing the seeds, the first seedling from the rosettifolia x sericea cross flowered...it was on what had been the most vigourous seedling all along....that plant later was named P. 'Rosemary Platz' after a dear friend. That first year, the plant had five flowers, but the foliage was really nice, and it shaped up very nicely.

Petrocosmea 'Rosemary Platz' in it's third season of bloom...now a mature plant. It has exceeded my hopes and represents three qualities that have now become standards that I select for in all of my Petrocosmea hybrids.....floriferousness, reluctance to form offsets, and attractive, ornamental foliage.

A mature plant of P. 'Rosemary Platz' just coming into flower. This hybrid has attractive foliage, showing the glossiness and lighter yellow veining of it's P. rosettifolia #3 parent. It gets it's leaf shape and size from it's P. sericea parent. An additional plus is that after three seasons of bloom, the original plant has never yet formed a single offset...a trait that I select for in my hybrids. The tendency to offset at flowering ruins many showplants...and is a nasty trait of the P. rosettifolia species used as a parent. P. rosettifolia #3 is the form with yellow veining that is least likely to offset. Form #4 offsets very heavily and is the form of this species that, for me, is the most reluctant to flower. By chance, I used form #3 in this cross.....that was purely an "accident"...but was a happy "accident".

My friend and hybridizing mentor, Dale Martens, took this photograph of a dissected flower of P. 'Rosemary Platz'. This photo shows the attractive purple stigma at the tip of the pistil, and the feathery white furriness of the filaments supporting the anthers.... both traits that neither of this hybrid's parents have. SO where did these traits come from???? ("Thank you" Dale, for allowing me to use your photograph!)

As my third year of Petrocosmea hybridizing comes to a close, I've been very happy with my first hybrid. I've been delighted at the response I've gotten from Petrocosmea growers and gesneriad enthusiasts in general about this hybrid and I hope that it will become a welcomed addition to the world of gesneriad hybrids. This year, I've attempted to take things to the next generation, as I've begun using P. 'Rosemary Platz' and it's siblings, as parents in new crosses. They are now forming seedpods....indications that they may be both pollen and seedpod fertile. I'm excitedly looking forward to the future to see how my "child" behaves as a "parent".

The Winter Solstice

Today marks the Winter Solstice in the Northern Hemisphere. That means that beginning tomorrow, the days will grow longer. Even though I grow my Petrocosmeas primarily in a basement room with no windows, and the lights are timed the same year round, the plants always have a way of sensing this natural cycle. It always amazes me that they know, but somehow they do.

Some species of Petrocosmea have an annual growth cycle that involves what I have come to term a "semi-dormancy". Right after the autumn and winter flowering period, the plants begin to decline. The outer leaves begin to yellow and will eventually wither. In the center of the plant, the crown of new leaves become thickened and tight...almost as if the plants have an infestation of cyclamen mites. They don't. This cycle repeats every year for some species, and they always burst into rapid, lush growth each spring. The species that exhibit this pattern of growth, for me, are: P. nervosa, P. sp. 'vittatae', P. barbata, P. formosa, P. flaccida, and P. rosettifolia forms #1 and #2. Some hybrids involving these species in their parentage will also show a modified "semi-dormancy". The hybrids exhibiting this modified semi-dormancy are: P. 'Momo', P. 'Asa Blue', P. 'Imperial Butterflies', P. 'Short'nin' Bread', and P. 'Fluffer Nutter'.




One of my two mature plants of P. sp. 'vittatae' after a heavy flowering period. I allow the plant to dry out more between waterings and keep the plant cool. I will groom the dead leaves and flower peduncles off the plant, and will not fertilize it again until I begin to see new growth from the tight silvery center crown of the plant next spring.

The tight, silvery crown of P. sp. 'vittatae' as it retreats into it's annual semi-dormancy. I allow the plant to 'rest' until this center crown begins to expand with lush new growth next spring.

A mature plant of P. barbata 'Keystone'. This plant has been a workhorse of bloom all summer and was the parent of two hybrid crosses when it produced seven full seedpods. It's is deserving of a winter rest. Note how the outer leaves are beginning to yellow. The center crown is taking on the tight, gnarled appearance of it's semi-dormancy. This plant is NOT dying, but resting. Allow it to stay cool, drier, and give it no fertilizer over it's rest. When the new growth begins to emerge next spring, it will make rapid, lush growth. By keeping the roots drier, you avoid rot and root loss. This preserves that large, mature root system, which will support a large, full head of leaves next season. This large rosette of leaves, will nourish a heavy bud and bloom set next season.

The tight, silvery center crown of a P. barbata that is entering it's annual semi-dormancy. The plant is not dying, merely resting.

As the Petrocosmeas wind down from a heavy season of bloom and enter this annual semi-dormancy, it is important to realize that they are not dying. This is a nature response to the changing seasons, shorter days and cooler temperatures of winter. The key to saving these plants is to recognize what is happening and to provide the proper care when this occurs. It is easy to rot the root system if watering is not adjusted. As the plant drops it's leaves, it requires much less water and nutrients to support life. Watering schedules should be adjusted to allow the plants to remain drier, with only enough water to support the very tiny center crown which remains. If done correctly, the mature rootmass will be preserved. This larger mass of roots, next spring, will support a much more lush, and rapid return to full growth. The rosette will be renewed in a shockingly rapid growth spurt. Once growth resumes, I remove any additional offsets or crowns and repot if needed. I DO NOT repot all plants. If a single crown remains and the plant is otherwise happy, I will simply remove the top quarter inch or so of soil and replenish it, add systemic pesticide granules and give the plant a weak fertilizer until new growth is well advanced. Then, I resume my normal care patterns.

Lastly, I will mention that plants grown on reserviors of fertilizer water using the wick watering method, and plants that are kept in a constantly warm environment may not experience this semi-dormancy as markedly as my plants. I attempt to grow my plants as close to what I think their natural habitat provides as possible, so I allow my plants to get quite cool, even cold by some people's standards. I also allow plants to dry out between watering and reduce fertilizers to the point that I am using only plain water for non-blooming plants at this time of year. This is why, I feel, my plants exhibit this pattern.

The Rosettifolia group - Part IV - Still One More!

In this post of the series on The P. rosettifolia Group from my collection, I will discuss the most reluctant to bloom of the four forms I grow. This form of P. rosettifolia is the one that I label #4 in my collection. It is most similar to form #3 in several ways, but is easily distinguished from form #3 when the two are compared side by side. This form has a tendency to form offsets more than any other form of the species. It's foliage can be the most ornamental, however it's reluctance to bloom and it's tendency to form offsets can make it a challenge to produce a beautiful, blooming plant of this form. In fact, this form never flowered at all for me last year. I had three mature, large plants in my collection and not one flower. They were all grown on the same shelf as the other three forms, all of which flowered heavily. This makes it unlikely that I will use it much in hybridizing. I maintain it in the collection for it's genetic diversity and scientific value.


The flowers of this form of P. rosettifolia have curled petals, deep green "hoods" formed by the upper lip of the corolla and a slight purplish blush to the lower petals.
The flowers of P. rosettifolia #4 have pistils that point upward, due to a curve at the midpoint of the pistil. All other forms of P. rosettifolia present the pistils horizontally and straight.

While the ligthing in this photo is too bright, one can still see the shape of the leaves of P. rosettifolia #4. In this form, the leaves have the attractive yellow central and lateral veining, however, the green is deeper, almost black with good lighting. Leaves are more narrow and the teeth along the margins are present only along the distal half of the leaf. The lower portion of the leaf at the base has smooth margins, without the teeth.

The pistil of the flowers of P. rosettifolia #4 has a curve at the midpoint. This causes the tip of the pistil to be pointed upright, looking almost like the horn of a unicorn emerging from the flowers. The pistil on the other three forms of P. rosettifolia in my collection have straight pistils, which present horizontally from the base of the flower.
The cymes of P. rosettifolia #4 have three bracts, as does form #3. Forms #1 and #2 have only two bracts. The bracts on form #4 are longer and more linear than those of the other three forms.

So there are at least four distinct forms of the species labeled P. rosettifolia in cultivation. I have also seen photos that may indicate there are still other forms of this species out there also. Each species has distinct morphological differences, and DNA testing done on the four forms in my collection does confirm that they are unique individuals within the same species. Judges should keep this in mind when judging this species, as the size and ornamental value of each form can be quite different, as can the propensity towards forming offsets. The amount of bloom for each form can also vary quite a bit.

I will likely be making a couple more posts in this series in the near future. As additional plants that I lump into this group come into flower, I'll review them. The "P. rosettifolia Group", so far, promises to be the largest grouping of individual clones of species and close relatives, that my, with time, be shown to be additional forms or varieties of this species. I place them all within this "group" due to morphological and DNA data. Admittedly, this is a group the I alone, have created, and more learned minds than mine may have different opinions on the subject. Still, other species being grown currently under other names, such as P. sp. 'Chinese #2' , sp. 'China 2005', and the species 'Yumebutai' are the current focus of some study in an attempt to identify proper placement of these individuals within the genus.