No sibling rivalry for Petunias

NOTE: THIS WAS ORIGINALLY PUBLISHED ON APRIL 1, 2013!

Petunias grown in a nursery together with their sibling petunias thrived much better post-separation than did a single petunia grown on its own. This conclusion jives with numerous studies which show that puppies kept with their litter-mates for at least 8 weeks develop better than puppies separated from their siblings soon after birth, and also fits with accumulating evidence showing the importance to human development of keeping a baby in physical contact with people, rather than isolating a baby in a crib.

Seeds of Petunia hybrida were germinated in two different environments. In the green house termed “Petunia Patch”, the seeds were sown 5 cm from each other.

Petunias in the "Petunia Patch"

In the second green house termed “Onion Patch”, individual petunias were planted at least 50 m from each other. 5, 10, 20 and 45 days post-germination, individual plants from the Petunia Patch were transplanted to the Onion Patch. Control plants remained in each plot from germination until the end of the experiment. Each plot received the same watering and fertilizer regimen. Growth parameters (germination rate, height, leaf number, flowering time, flower diameter, seed set) were gathered daily over a two-month period.

The results were astounding. The longer the petunia stayed in the Petunia Patch, the more the individual plants thrived (see graph on left). The effect was especially significant for the first 10 days. Most of the petunias germinated in the Onion Patch, or transplanted early in life, failed to thrive. When asked to comment on the flowers that didn’t bloom, Drs. John N.Kamano, William E. Faber and Maurice Merl  said, “They were just lonely little petunias in an onion patch”.

These results have implications for home gardeners who are asked to purchase neighboring petunias in their local nursery so as to lessen the separation stress of plants upon leaving the nursery.

Guest Blog: Yunal Sapir and The Shy Red Bride

Anemone coronaria

Dr. Yuval Sapir is Director of the Tel Aviv University Botanical Gardens

The red-crowned anemone, Anemone coronaria, is one of the most common and beloved wildflowers in Israel. It's Hebrew name, Kalanit, is from the Hebrew word for bride, dressed beautifully in a red dress. From January through March, red carpets of anemones cover the hills in the Mediterranean region, with beetles buzzing in and out the flowers. These are glaphyrid beetles that are adapted to forage pollen and to mate on the red, bowl-shaped anemone flowers. The beetles are attracted by the large amount of pollen in the numerous anthers of the flower. While eating or mating inside the flowers, their body is covered with pollen grains that transferred on to the next flower.

Anemone flowers live for two weeks, but only in the start is the stigma receptive to accept pollen grains. Although the flowers are hermaphrodite, containing both sexes in the same plant, the female (stigma) is matures earlier than the male (pollen), effectively mandating that sex has to be between two different flowers. When the male function is active in the flower, there are other younger flowers that have their stigma ready. Interestingly, during its two-weeks life time, the anemone's flower keeps growing. Young, female flowers are small and perfectly red. Later on, the male flower is larger and also develops white ring around the center where the pollen is available for the pollinating beetles. Of-course, the male function of the flower benefits from being prominent on the white background. The more seen, the more visits and the more pollen grains spread out to females. The female function, on the other side, needs very little number of visits, because one pollen grain fertilizing an ovule is enough to make a seed. So no need to be prominent like the male; the small red flower is just enough to get pollen. The shy female will get what it needs soon enough.

Guest Blog: Yuval Sapir and 50 Shades of Pink

A field of wild anemones flowering in early January.
Note that most of the flowers are not red.

Dr. Yuval Sapir is Director of the Tel Aviv University Botanical Gardens

The crowned anemone, Anemone coronaria, is well-known for its red flowers. But its flowering season, January to March, is also characterized by non-red anemone flowers, particular early in the season. 

While the red flowers are pollinated by glaphyrid beetles, the non-red ones are pollinated by any possible insect hovering around in the winter. All except beetles. But no worries - beetles are anyhow not around in this early period of the winter (January). Indeed, the non-red anemones flower earlier than the red ones, even where they grow in the same place. 

Another difference between the two types (red and non-red) is that while the red ones are common everywhere, from extreme desert to the northernmost Mediterranean parts of Israel, the non-red anemones are unique to humid Mediterranean ecosystems. This is probably due to drought tolerance trait linked to the red-color allele. The genetic system for the color of the anemone includes two possibilities (alleles): red, or non-red. Red is recessive, this means that a only if both alleles are red, the flowers are red. If one of the alleles is non-red, the flower will be any other shade of pink, from white to purple. Despite the superiority of the non-red alleles, they are non-exist in the southern populations, in the dry Mediterranean and in the desert. This linkage between flower color and environmental adaptation is interesting, and has not been extensively studied.