Natives and Exotics
By Donna Porter
It is no exaggeration when we say that Costa Rica is a plant paradise. We, literally, live in the wonderful world of plants. Costa Rica contains over 5% of the world’s biodiversity of flora and fauna, while encompassing only .025% of the earth’s land mass. To put the country more into perspective (at least for those who know U.S. geography) it is about 4/5 of the area of the state of West Virginia, which is the 9th smallest U.S. state. Costa Rica consists of 12 different, eco-climatic zones, which range from the coastal lowlands to the cloud forests. Within these twelve zones grows over 11,000 species of native, vascular (has a xylem and phloem – not including mosses, lichens, etc) plants, including 1,500 species of trees, 1.300 species of orchids, 800 species of ferns and 200 species of bromeliads. These very impressive numbers have been attributed to the location of the country. It has been defined as a “bridge” between North and South America, which links these two continents together. For this reason it is believed that Costa Rica has inherited an astonishing diversity of plant (and animal) species from both continents.
Along with these astounding numbers of native plant species that arrived in the country thousands of years ago, there are thousands of more of exotic plants from other parts of the tropical world that grace the country and flourish here. These plants have managed to traverse the globe without the use of any movable appendages or abilities to navigate machinery (at least not that I am aware of). They have also managed to be discovered, uplifted and then transported, as far as half-way around the world, by plant explorers of past and present centuries.
It is estimated that at least 75% of the ornamental plants that are typically used in our gardens and landscapes are “exotics”, meaning that they have originated in other parts of the tropical world and have, one way or another, found their way here to Costa Rica. Some of these exotics were introduced during times of New World explorations by Europeans, four to five hundred years ago, and have “naturalized” in the forests and along roadsides, but are not, technically, considered native/indigenous species.
A native plant is a plant that existed in an area before the arrival of foreigners – the same as native or indigenous people. Scientists and plantsmen have researched and documented this information for centuries. All plants are native somewhere, unless, they are hybrids or grafts which are created by the intervention of man. Hybrids are hand-pollinated crosses between two parent plants, which results in seeds that produce plants with characteristics of both parent plants. These “crosses” are usually performed in greenhouses or other areas with controlled conditions. Grafted plants are plants produced by splicing and interconnecting a stem (called the scion), or even just one mere bud, to another desirable plant’s roots (called the rootstock). Many fruit tree varieties (mangoes, citrus, apples, avocados) are produced in this manner, and again, result in a tree with the desired characteristics of both parts.
A weed is defined as “a plant that is growing where it is not wanted and can potentially overgrow desirable plants”. In their place of origin, many beautiful garden plants that we consider desirable, pay good money for at the nurseries and use in our landscapes are considered weeds. Interestingly enough, this is what we call our native plants. As the saying goes, “what’s one man’s trash is another man’s treasure”, is true with plants also. What our local gardeners consider weeds and call “monte” are more than likely a native plant and chop these down without thinking twice.
Maintaining or re-introducing native plants into your garden or landscape, in combination with your exotics, is a good idea. The problem is that very few nurseries offer them for sale, at least not here in Costa Rica. Digging native plants from the forest to incorporate into your garden should only be done when there is an abundance of that species, or the species is very common and you are only going to be removing a very small fraction of a colony.
Being a Horticulturist and a garden designer, I simply adore the wide variety that the exotic plants bring to my palette for use in designing. I also understand and appreciate the grand importance that the native plants play in maintaining the balance of the ecosystem and the problems that can arise when exotics become invasive. Exotics can become invasive when the growing conditions to which they have been introduced, are more optimal for growth than where they originated from.
Maintaining a balance of the area’s native flora in the landscape is important because the native fauna (insects, animals, reptiles) are more accustom to sustaining themselves on the native flora, although in time some adapt to the exotic species. The native flora, obviously, is also more adapted to this climate and therefore requires less water to maintain. A few of the popular natives (for this region of CR) are: Heliconia latispatha (which is prolific), Heliconia wagneriana (photo) – both are called Platanillo in Spanish, Calathea lutea/Bijagua, Aphelandra scabra/Pavon, Brassavola nodosa/Huelenoche – an orchid and Muntingia calabra/Capulin -a great tree for attracting birds.
Among the most troublesome invasive exotic plants in our area is Thunbergia grandiflora/Jalapa Azul, which has origins in India. This vining plant has clusters of large, lovely blue flowers and will rapidly cover a fence, wall or other plant. If planted in an area near the forest, it can become a problem by smothering out and overtaking neighboring native plants. It is best to confine it to your landscape or garden or remove it altogether and replace it.
The future botanical garden will be a testing ground for new exotic arrivals to reveal if they “behave” themselves in our climate before they are released to the nursery trade for propagation and sale. The Native Plants garden will showcase the indigenous plants of our coastal lowlands and provide a safe source for propagating natives which we can then offer for sale to the public in our garden gift shop.
Donna is a Horticulturist and has been living and working in Manuel Antonio for 8 years. She consults, designs, installs and maintains gardens for private homes and hotels and also develops botanical trails. Donna is the founder and first Director of the Botanical Garden of the Ozarks and is pursuing the development of a botanical garden in, and for, the Quepos area. [email protected], 2777-5149.