It was another beautiful sunny day in
Israel and I had
decided to go outside Jerusalem to see the Dead Sea like all well behaved tourists do. Just before I
get there, I have decided to walk around in that inspiring desert environment
that surrounds the area, right close to Ein Gedi. After passing by a family of
wild gazelles that made me company for few minutes, I stopped by a wonderful
tall shrub. I was standing by a stunning member of Apocynaceae. The plant was Calotropis procera and their flowers, as
usual, took the breath out of me! They were fleshy, big and colourful and the only
thing I wished was to have someone with me so I could share all my thoughts
about those flowers. But there was nobody passing by for as long as I stayed in
the area, and the gazelles wouldn’t understand my excitement about their food,
so I stay just admiring them for while. In such a harsh environment, the last
thing I was expecting to find was such showy purple flowers – that shrub was
just like an oasis of beauty in the desert.
|On the left side: the gazelle happy family; on the right side: the shrub with the Dead Sea on the background|
My astonishment was nothing but the proof of my infinite ignorance: these plants are actually quite common, especially the
Dead Sea region. They are
commonly called the “Apple of Sodom” because of the characters of the fruits,
which are as big as apples and because of their dehiscence. The fruits are described
as “exploding” or “dissolve into smoke and ashes” when you try to pluck them,
possibly remembering the biblical scriptures of the destruction of Sodom and Gomorrah.
This happens only because the fruits are hollow, but unfortunately didn’t have
the opportunity to see them “dissolving” on my hands as the plants were not
fruiting yet. The seeds produce silky strands which can be used as wicks for
oil lamps, except in Jewish Shabbat lamps, according to the Mishna. These
strands may also be used as natural textile fibers for other purposes. This
biblical plant, as a member of Apocynaceae, produces a toxic milky sap, so be
careful while handling it!
|Fruits of Calotropis procera (Source: Flowersinisrael.com)|
Unfortunately I didn’t dissect any flowers, so I don’t have good pictures to show morphological characters, but I will try to make it understandable. In Asclepioideae (old Asclepiadaceae family, today a sub-family of Apocynaceae) there is a structure called gynostegium. The gynostegium is the fusion between stamens and stigma and it is only known to be found in this family, however it resembles another structure appearing in a totally different family: Orchidaceae. The structure described in Orchidaceae is the gynostemium, and is also described as the reproductive structure of Aristolochiaceae. But the difference between a gynostegium and a gynostemium is not easy to detect, it is a matter of timing of fusion during the development of the flowers. While in Orchids and Aristolochiaceae the fusion between stamens and style is congenital, in Apocynaceae the same fusion is postgenital. But the problem now is to understand the difference between congenital and postgenital fusions.
|Flower detail of Calotropis procera|
These terms might be confusing to explain and understand, so to make it simple I would just say that the real fusion is the postgenital fusion, as we can identify it as a fusion. In postgenital fusion the organs develop independently until a certain point where they start fusing to each other by marginal adhesion. In congenital fusion you cannot see this for the simple reason that the organs are actually growing and developing together since the beginning.
It seems sometimes that botanists like to make up random names just to make other people, but terminology is a useful tool. In this case the names are so similar that they can without a doubt become a misunderstanding problem easily! The truth is that humans try to understand Nature the best they can by inventing names to communicate with other people, share knowledge and think together. But then we have to interpret the words we’ve created to try to understand plants – at the end it seems that botanists just like to play word-games. And it is much more fun to use words hard to pronounce.