1. Yellow & Purple Lady Slippers
Yellow and purple lady slipper flowers are native to the UK and other countries in Europe, including Spain. Although single-colored yellow lady slippers are common, there is now believed to be only one place where the yellow and purple variant is growing - a hidden spot on a golf course somewhere in the north of England. Efforts to protect these last remaining examples in the wild are so intense that the exact location of the flowers is a secret and they have been under police protection for decades.
The Middlemist Red is often considered to be the rarest flower in the world, with only two known examples existing anywhere - whether in the wild or in a protected environment. One is found in New Zealand and the other at Chiswick House in West London, and plenty of visitors are keen to get a glimpse of its beautiful pink petals (the red in its name is something of a misnomer).
Jade vine is a very rare flower found mostly in the rainforest of the Philippines and a few other locations. It has claw shaped flowers, which vary in color from blue to light green. The vine's stem can grow up to 18m (60 feet) in length and the flowers droop down to be pollinated by bats who hang from the trees that host the plant. The wonderfully colored petals become particularly special at night, when they radiate with a luminous glow in the dark forest.
4. Kadapul Flower
The kadapul flower is found mostly in Sri Lanka, and is often considered to be the most expensive flower in the world, for two reasons. Firstly, it only blooms at midnight, before withering again by dawn, and secondly, it dies pretty much as soon as it is picked. This means they can't really be sold, and are essentially priceless. Not many people in the world get to see this rare flower bloom, or smell its wonderful scent. It is held in high regard in Sri Lanka and has various nicknames including 'Flower from Heaven' and 'Queen of the Night'.
5. Youtan Poluo
The existence of the youtan poluo was for many centuries believed to be nothing more than a myth, until a Chinese farmer called Mr Ding found examples of these tiny, white flowers, which measure no more than 1mm in length. The flowers are mentioned in Buddhist scripture but only bloom once every 3000 years, so you have to very lucky to see them. It is native to China and Taiwan, as well as the Koreas, where it has been found growing on a statue of Buddha at the front of the Chonggye-sa Temple in Seoul.
6. Ghost Orchid
The ghost orchid, so named because of the shape of its petals, is most commonly found in areas of Cuba and Florida and is extremely fussy about where it grows. It requires very specific host trees to grow properly, and conditions need to be perfect for it to flower. This ensures that its flowering times are very unpredictable, so not many people are lucky enough to see this odd flower in all its ghostly glory. The few examples that exist in the UK are protected, and anyone caught removing one can face a jail sentence!
7. Chocolate Cosmos
The chocolate orchid is endemic to Mexico, but is now sadly believed to be extinct in the wild. The plant is so named because the odor it releases when it blooms smells of chocolate. There is only one example of this unique, maroon flower in existence today, a clone grown by scientists using a technique called vegetative propagation.
8. Corpse Flower
The corpse flower also takes its ghoulish name from the smell it releases when it blooms. Unlike the chocolate orchid, it is not an odor you would normally seek out, as it is often compared to rotting flesh. They are parasitic plants, which attach themselves to hosts to obtain water and nutrients, and the odor they emit does serve a purpose because it attracts flies and other pollinators. They can grow up to 3 feet (1 meter) tall and weigh up to 15 pounds (7 kilograms).
9. Parrot's Beak
The parrot's beak is another flower named after a visual resemblance, and is endemic to the Canary Islands. However, it is now believed to be either extinct, or close to extinction, in the wild, because the sunbird - its only pollinator - has long since gone from the islands. They have rarely been found since the 19th century and only bloom in full sunshine, revealing fiery oranges, reds and yellows when they do.
10. Gibraltar Campion
The campion can only be found on Gibraltar. In 1992 it was declared extinct but it has since 'come back from the dead', after being discovered growing on a nature reserve in 1994. Hearty efforts have since been made to preserve the remaining examples and reintroduce it to other areas so that its subtle scent and bright flowers that range in color from white to pink, can continue to be enjoyed.
11. Kokia Cookei
Last but not least is the kokia cookei, the flower of a small deciduous tree found only in Hawaii. There has only been one wild example of kokia cookei found in the last century, making it one of the rarest plant species in the world. The example that did exist was destroyed in a fire in 1978, but a branch had been removed earlier and was grafted onto a related plant to ensure its survival. There are now around 23 grafted examples of the plant in existence.