In Chile, there are nearly 6.000 species of vascular plants (with a basic structure of root, stem and leaves), from which more than 700 are introduced plants dispersed across native ecosystems. It’s important to highlight that about 50% of native species are endemic, which means they naturally grow exclusively in Chile. In comparison to other South American countries, the whole of species is not very high, but the level of endemism is one of the highest in the continent, partially due to a mark geographic isolation, like the Atacama Desert by the north, the Andes Mountains by the east, the Pacific Ocean by the west and, finally, the Drake Passage separating Chilean Patagonia from the Antarctic Peninsula by the south.
Because of its geographic isolation and particular geoclimatic history, Chile has a large diversity of ecosystems, from which many have extreme conditions. Some examples of this are the Flowery Desert phenomenon in the north, and the cold and hostile high Andean landscapes where there’s barely little vegetation. How did a large amount of endemic species make it to settle in these habitats?
Among angiosperm (flowery plants), is the Orchidaceae family, one of the largest in the world with around 25.000 species. Orchids make one of the most grown groups in the world, but little is known about their strategies and ecological adaptations. In Chile there are more than 70 native species recorded, found from Tarapacá to Magallanes and Chilean Antarctica regions. Among them, a little more than a half are endemic, with one particular species only found in the Alejandro Selkirk Island from the Juan Fernández Archipelago.
These plants have a unique morphology that distinguishes them from other angiosperms, as they have roots, leaves, and also, modified flowers reflecting their evolutionary history. One of the pollination mechanisms from these flowers is by aroma (the most evolved one), pretending to be nectar producers. But most orchids use a method where they deceive pollinating insects to think that the flower is a female insect ready for mating. One single orchid can produce thousands of microscopic seeds without cotyledons, they only have a core. In the absence of energy to germinate on their own, they must build symbiotic relations with specific fungus in order to germinate and grow. They keep this relation until the plant is able to create chlorophyll on its own (being autotrophic), and that is the place where the fungus is fed by the plant. It is important to indicate that, in nature, the birth of an orchid would not be possible without the presence of a supporting fungus, nonetheless, for these fungus, orchids are not essential for living.
The roots of orchids have an internal filament covered by a mass of spongy cells called a velamen, whose role is preventing loss of water in dry environments and a better absorption of water and nutrients. Not all leaves from orchids are the same, they range from succulent and spongy to thin and fragile, which are normally covered by a dense layer of cutin (cuticle) that protects the plant from excessive evapotranspiration and defoliators (insects, larva or animals eating leaves). The flower from orchids is their most distinctive morphologic characteristic and it normally consists of three external parts and three internal parts. The three external parts are sepals and they are organised in one on the upper section and two on the lower section, while the internal ones are petals organised as two at each side of the flower and one at the bottom or lower part, called lip and highly modified in order to assist in pollination.
Finally, another highly specialised structure is the pillar, which is succulent and is about the merger of the flower’s female part (gynoecium) and male part (androecium).
These plants are constantly threatened by road construction, stamping caused by livestock, plough for crop soil preparation, and change in the use of soil, among others. Also, it must be added the competition for the use of valuable available resources (soil, water and light) with introduced species of flora. Given the large quantity of anthropic threats and natural difficulties for these species to adapt, it’s our duty to protect and look after our native orchids, which are a patrimonial treasure and have managed to adapt to the extreme environmental conditions we have in Chile.
Authors: Josefina Arce (Bachelor of Environmental Science, jsfnrc@gmail.com), Gustavo Morales (Native Orchid Researcher, glasspalacechile@gmail.com), and Hernán Retamales (Forestal Engineer, PhD in Botany, hretamalesr@gmail.com). Photography: Gerald Poblete (Nature Photographer, gerald.poblete91@gmail.com)