Boissier’s Barbbell – Trichodesma boissieri

01 Jan

How many light-blue flowers do you know? And we do not mean  violet-blue or dark blue, but real light-blue! Our plant of the month – Boissier’s Barbbell – is laden with unique and beautiful light-blue flowers, which you can see in the desert section of the tropical conservatory.

Trichodesma boissieri
Trichodesma boissieri

Boissier’s Barbbell is a rare plant that grows only in the Jordan Valley and the Dead Sea Valley. It is a perennial herbaceous plant, whose leaves are covered with delicate silvery hair. This is the plant’s way of adapting to the hot sun – the light hairy cover helps reflect the sunlight, and allows the Barbbell to absorb less heat and loose less water.

The Barbbell’s flower is unique: 5 petals, arranged in the shape of a star, with a delicate kerchief texture. Their color, as mentioned, is beautiful light-blue, and in the base of each petal is a pattern of brown-yellow triangles, so it looks like a necklace of triangular beads in the flower’s center, surrounding the style and stamens.

Trichodesma boissieri
Trichodesma boissieri

The flower blooms “upside down”, like the Cyclamen’s flower: the petals are rolled up backwards, while the style and stamens are seen below. The pollen is capsuled inside the stamens, it does not disperse and is not available to every insect that comes to the flower. So how is this flower pollinated, and how does it produce fruit with seeds? The bee that approaches the flower holds on to it with its mouth and rapidly vibrates its wings with a strong buzzing sound. This buzz creates resonance that shakes the stamen and make the pollen pour down (just like salt from the holes in a salt-shaker). Some of the pollen drops on the bee. When this bee will visit a new flower, it will touch its stigma, and thus pollinate it. This pollination method is called “Buzz Pollination”. The bees that specialize in this method are mostly large and strong, such as bumblebees. There are other flowers that use this pollination strategy – the most known ones are those of tomatoes, eggplants and potatoes.

Note also the fruit, in the fruiting stage the bell-shaped flower is much enlarged, in it is the fruit that is composed of four mericaprs – each is plate-like, ovate.

Trichodesma boissieri
Trichodesma boissieri

Boissier’s Barbbell is named after Pierre Edmond Boissier, a Swiss botanist, who researched the Middle Eastern Flora in the 19th century. Boissier was an important botanist, who published the five volume “Flora Orientalis”, that contains information about approximately 12,000 plants from our region, half of which were described as new to science.

We planted the Boissier’s Barbbell in the desert section of the Tropical Conservatory, and it adapted well, blooming continuously all year! You are welcome to visit the Conservatory, which is open daily from 9:30 to15:00, and is full of wonders and surprises!

Written By: Yael Orgad, January 2020

Top