1. Dragon's blood tree — Socotra, Yemen
Much like the Galapagos Islands or Madagascar, the Yemeni archipelago of Socotra is home to some of the strangest flora and fauna on Earth due to its many years of geological isolation. As a result, about 37 percent of the 825 plant species on Socotra are endemic, including the famous dragon's blood tree (Dracaena cinnabari).
While this odd, umbrella-like tree has an ominous name (a reference to the dark red sap it produces), the only thing spooky about it is its conservation status.
Currently, the tree is listed by the IUCN (the International Union for Conservation of Nature) as "vulnerable" due to the increase of development and tourism on the island. However, recent local and international conservation efforts to protect this strange yet gorgeous tree are an encouraging sign that this is one species that won't go the way of the dodo.
2. Grandidier's baobab — Madagascar
Of the nine different species of Adansonia (commonly known as a "baobab") found throughout the world, six of those species are endemic to Madagascar. Sadly, three of Madagascar's baobab species are listed as endangered on the IUCN Red List, including the largest and most famous of them all, the grandidier's baobab (Adansonia grandidieri).
So what is threatening these grand, bulbous monoliths? A variety of things, though the main culprit appears to be the rapid transformation of the surrounding environment. What was once a rich, diverse ecosystem of Malagasy forests has given way to agricultural fields that divide and separate baobab populations, making it difficult to sustainably propagate future generations.
As Scientific American reports: "Many baobab trees currently reside in Protected Area Networks (PANs) established to preserve Madagascar's biodiversity, but the areas outside many PANs have been almost completely converted to agriculture or cattle grazing areas, leaving no room for the trees to expand their distribution. In addition, the large animal species such as elephant birds, which may have eaten baobab fruit and carried the trees' seeds several kilometers from where they first fell, have all now gone extinct."
3. Monkey puzzle tree — Chile and western Argentina
These peculiar South American evergreens are often likened to pine trees (one of their common names is the Chilean pine), but Araucaria araucana is not a true pine. It's actually in a family all its own — an ancient family, as a matter of fact. Araucarians like the monkey puzzle tree are often described as "living fossils" because they haven't changed much compared to their ancient ancestors.
The quirky "monkey puzzle" name came about in the mid 19th century when Sir William Molesworth, who acquired one of these trees for his garden in Cornwall, showed off the novel specimen to a group of friends. One of Molesworth's friends, a barrister name Charles Austin, noted the strange, spiky trunk and branches and commented that "it would puzzle a monkey to climb that."
For many years, the main threat to the monkey puzzle tree was logging, and while that practice was made illegal in 1990, the 60 percent of trees that remain in the wild continue to struggle due to other threats like seed collecting, animal grazing and unique issues stemming from their geographic locations.
"There are severe threats to Araucaria araucana in the north of its range in Argentina, due to the establishment of plantations of exotic tree species within these native stands," according to the monkey puzzle tree's IUCN Red List entry. "In Chile, the main threat is anthropogenic fires: large areas in several national parks have been destroyed within the last 25 years."
Sadly, with their poor rate of regeneration, it can be difficult for these gorgeous trees to make a sustainable comeback.
4. Quiver tree — South Africa
This strange-looking tree, which belongs to the aloe family, is primarily found along South Africa's Northern Cape region as well as in select parts of southern Namibia.
Although Aloe dichotoma is known to the indigenous San people as "Choje," the English "quiver tree" name references the way these hunter-gatherers hollow out the branches to create quivers for their arrows.
There are three subspecies of quiver tree — dichotoma (pictured above), pillansii and ramosissima — and all three are listed on the IUCN Red List as a result of climate change.
The species with the most dire situation is A. dichotoma pillansii, which is critically endangered. There are estimated to be fewer than 200 pillansii individuals left in the wild, and with little recruitment of younger plants coupled with older dying plants, the future of this subspecies is bleak.
One of the best places to see a quiver tree in person is at the Quiver Tree Forest near the Namibian city of Keetmanshoop. The forest, which was declared a national monument in 1995, is spontaneous, which means it was propagated naturally. The tallest trees in the forest are between 200 and 300 years old.
5. Candelabra tree — Southern Brazil
Candelabra trees, also known as Parana pines or Araucaria angustifolia, are striking, chandelier-esque evergreen trees native to southern Brazil.
As yet another living fossil from the Araucariaceae family, the candelabra tree split off with its nearest relative, the monkey puzzle tree, back when Australia, Antarctica and South America were a single continent.
Despite its long history, the exquisite tree species may not be here for much longer. Due to logging, agriculture and over-consumption of its fruit and seeds, the tree species has lost a staggering 97 percent of its population within its 90,000-square-mile natural range since the beginning of the 20th century. As a result, it is listed as critically endangered by the IUCN.
Even as the trees continue to disappear from the wild, their unusual appearance and symmetrical growth patterns make them a popular tree for inclusion in subtropical garden landscaping.
6. Cucumber tree — Socotra, Yemen
Characterized by its pale, bottle-like trunk, the cucumber tree (Dendrosicyos socotrana) is a species endemic to Socotra — the same Yemeni archipelago where dragon's blood trees are found.
Like many species that develop on isolated islands, the odd tree species is increasingly threatened by man-made forces — in this case, agriculture. Non-native animals such as goats are often allowed to graze on the tree, which impedes germination and growth. In addition, the trees are often cut down in times of drought and used to feed livestock. This kind of agricultural pressure has led the IUCN to list the species as "vulnerable."
Thankfully, not all cucumber tree individuals are threatened. When
they're surrounded by a patch of dense shrub vegetation — such as fellow
endemic species, Lycium sokotranum and Cissus subaphylla (pictured above), the trees are more protected from the grazing of goats.