Mendelian miracle in the garden

Orange-pink ruffly double is the resulting hybrid of (yellow-orange) hibiscus rosa-sinensis x (red) double hibiscus rosa-sinensis.
Yellow-orange pod parent
Double red pollen parent
Double red pollen parent
Zooming in on the frosty pink colour in the centre of the flower in its eye zone.
Zooming in on the frosty pink colour in the centre of the flower in its eye zone. The pink rays out into the veins of the petals. This seems to explain the undertone of pink in the flower’s dominant light orange colour. But a strange thing happens to this flower’s colour palette in sunlight. The flower petals, as in this pic, seem to reflect some of its pod parent’s yellow colours.
In sunlight
In shade

Imagine this. His name was not Gregor. It was Johann, the name his parents had given him. The Mendels were farmers who wanted their son to take over their farm. But Johann Mendel was depressed because what he wanted from life his family could never understand. He was sensitive and liked the quiet. Left to himself in his own private world, he was free to ponder the mysteries hidden in his parents’ garden and the wider cultivated world of their farm. He read, studied and saw minute things in the plants that no one thought important enough to notice. To others he was strange, his interests and studies wasteful, costly and unprofitable. The strain of breaking away from the people he loved so much, the people who couldn’t understand him, proved too much. He had to break down and remake himself again to find his own path in life as a scientist.

As he was not upper middle class or an aristocrat, where could he find the resources to pursue science? He  decided to join a monastery as that was the only way in those days that an ordinary man like him would find the resources to conduct his researches. He became an Augustinian monk and received the name Gregor. His new life began. The monastery funded his education at the University of Vienna. Later, he began teaching and went to work in the monastery garden among snow peas and his experiments in genetics started in earnest. Things he had noticed in his rural childhood now combined with the expert botanical knowledge he had acquired at the university.

Pod parent in shade, flower still not all the way open: Hints of pink here too, but it is more strongly expressed in the hybrid double flower offspring. Here in the parent, the orange colour seems to rise out of its eye zone into the veins of the petals. In its offspring, in contrast the frosty pink is what you get in the eye zone of the flower.

In school, we learned evolutionary biology in a dry classroom setting with drawings in text-books not conducive to imaginative empathy. Despite this, to me the subject was fascinating. I kept crossing the various characteristics on paper for days—Rr, rr, rR, RR and on and on it went for all the different alleles in so many different permutations: tall-short plants, smooth-wrinkly peas, yellow-green peas and flower colours. Only now after all these years, can I picture him—Gregor Mendel—strolling through his garden finally at peace, soaking in the mild scents and the silence he treasured. He is surrounded by pea plants, their curling tendrils reaching toward him as he passes.

I grew snow peas in 2013, and I know it requires skill, which I did not possess, to cross them. Pea plants keep their mating structures inside a keel petal, which has to be carefully, delicately sliced open to cross pollinate. And you have to know just when to do this, before the flower self pollinates. I did not have the patience to attempt it then. Hibiscuses are easier to attempt crossing on, using little paint-brushes to paint pollen on their stigmas, which have evolved into landing-pads to welcome visiting insects.

I waited more than a year for my little hibiscene garden miracle. As I am not an organised record keeper, and I only wield my paint-brush pollinator if my two parent hibiscuses happen to flower on the same day, I can’t really be sure of the dates. Fickle memory tells me the cross pollination via paint-brush happened in December 2013 (Decembers in Pune are dry and cool), the seeds were collected around March-April 2014. The plant doesn’t always set seed. It’s fussy, the conditions have to be just right for pod formation: an older plant is more likely to make pods, they need a lot of good quality compost, when making pods they like cool weather, and the plants hate harsh sunlight. I got about two seeds from one pod, and three from another. The plant, in pic number 3, is the only one that made it through the extreme heat of June and early July 2014 here in Pune, followed by a heavy monsoon and other travails and absences in my apartment garden.

The offspring that survived all this is now displaying signs of that famous F1 hybrid vigour. Its leaves are a leathery over-sized green, the long-awaited, much longed for first flower that played dice with my patience is large and showy, and it bloomed out a delicately orange ruffly petal frock with some frosty pink at the waist, I mean, its eye zone. Hibiscus flowers are usually bisexual. But the flowery product of my cross is most likely sterile as it seemed to be missing its style and stigma. After the flower dried and fell off during repotting, I slit it open to discover its ovarian aspect undeveloped making it almost male. I scanned the internet looking for reasons and hit a few scattered paragraphs in different places.

Some hybrids are indeed sterile, and the double flowered hibiscus rosa-sinensis has genes that turn stamens into extra petals or even smaller petaloids in some cases. Lo and behold, in my ruffly orange wonder the upper half of the stamen tube or the whatyoumacallit seems to have transformed into extra petals, the lower half did yield some anthers upon closer examination and the entire upper half of the pistil, with those marvellous insect heli pads, is missing. I don’t know if those genes responsible for both stamens and extra petal formation in a double flower somehow also hindered the development of the gynoecium or the female parts in this flower. Remember not all double flowers are sterile. The pollen parent of this one is a red double hibiscus, which had all its female parts intact. Given good compost, a better, bigger pot, and the right conditions it can make seed. Its offspring, however, may have received a few extra genes due to polyploidy (explanation in last paragraph) so now it will have to be propagated via cuttings.

Hairy hibiscus seeds from my yellow-orange hibiscus collected in 2012. These seeds were a result of self-pollination. Only plant managed to survive from this grouping but it didn't survive a shift from one terrace to another, dropped all its leaves, then  died from overwatering in my absence.
Hairy hibiscus seeds from my yellow-orange hibiscus collected in 2013. These seeds were made most probably by self-pollination. Only one plant managed to sprout from this triad in 2013, but it didn’t survive a shift in its position.
The 2012 seed sprout.
The 2013 hibiscus seedling, its seed leaves vaguely reminiscent of Ginkgo leaves.

Anyone who keeps plants knows this—fussing amongst them is a kind of focused meditation. When you are with them they connect you to the earth and it’s poetry without words, mystical reverence without religion. Sometimes that’s all you can ask for from this life in the midst of self-seeking melodrama and mindless noise, to be able to listen when all the leaves of all the trees in your neighbourhood play softly in the breeze under a baby blue sky.

This particular species of tropical hibiscus, the rosa-sinensis, seems to be polyploid in its gene structure. In other words, during cross pollination gene combinations from the two parents result in more than the usual two gene sets. Instead of making the normal two sets from the immediate parents, all the genes from all previous generations seem to become available as add-ons leading to multiple sets of genes and incredible variety. It’s nature’s lucky draw. But this often leads to sterility as in the sunset-hued wonder in my garden, though sometimes not, if you are a fortunate gardener. Apparently, you never get the same flower type twice upon crossing. Each cross makes each seed in the resulting pod unique, with a brand new though related plant and flowering type just waiting to happen. Imagine this, if each of my five seeds had survived to maturity, they would have produced five different plants and five quirky flowers. Fact would have been stranger than any fiction I could have come up with.

My golden sweet snow pea from last year. This makes me feel ever-so distantly connected to Mendel's garden.
My golden sweet snow pea plant from 2013. This makes me feel ever-so distantly connected to Mendel’s garden.

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