In the last article, plant hunter Seijun Nishihata described the unique plants and beautiful scenery found only in cold countries. In this third installment of the series, he talks about the plants of hot countries. So, what are the characteristics of plants that live in hot and humid environments, and how do they noticeably differ from those in cold regions?
Plants Continue to Grow When Temperatures Remain Optimal
As it is getting warmer now, I would like to pivot and talk about plants in hot countries, which include tropical, subtropical, desert, and arid regions. If we were to group the tropical and subtropical regions together, we would see a diversity in plants that is so great that it accounts for the majority of all land plants on Earth, both in terms of species and population. The exceptions to this are desert climates, arid regions, and savannas, where there is precious little rain and almost no plant diversity.
From a Japanese perspective, plants go through distinctive changes between growth and dormant periods as seen in the cycle in which plants form buds and bloom in spring, grow into lush greenery in summer, change colors and are harvested in autumn, and lie dormant in winter. However, plants in the tropics and deserts do not undergo this type of cycle. Because of the stable temperatures in tropical and subtropical regions, plants always remain in a growth phase. In other words, they continue to grow without rest from the moment they emerge into the world until the moment they die and have offspring. I think this is what makes them completely different from plants in other climate zones.
One particular aspect of plants in deserts and savannas is how they may have to wait months for just one rain shower. When rain finally does fall, thousands, tens of thousands, hundreds of thousands, or even millions of buds suddenly appear, transforming the land into a grassy green field. This dramatic occurrence could be said to be one of the characteristics of these types of plants.
Coexistence with Others in a Competitive World
Unlike the plants of cold countries, plants of tropical regions give a colorful impression. In fact, their appearance closely integrates with their survival strategy. To preserve the species, plants must have someone, or something, carry their pollen. This is accomplished by one of three ways: wind pollen, in which wind carries the pollen, bird pollen, which is carried by birds, and insect pollen, which is carried by insects. However, in tropical regions, there are huge varieties of trees and plants, and it can be difficult to get noticed.
This is why the plants must have a conspicuous trait such as generating flowers that attract birds, having brightly colored fruit, or releasing a sweet fragrance. These qualities entice birds and insects into tasting the nectar and carrying seeds off in the distance. Because tropical regions are home to an array of insects, birds, and other creatures, plants can gain suitable partners in a variety of ways. This leads to colorful sceneries of different shapes that people see and stands in stark contrast to the monochromatic vegetation of cold countries.
Importance of Humidity to Plants
Conditions that are comfortable to humans are the same for plants and include not only temperature, but also humidity as a major factor. Some tropical plants of hot countries have adapted to living on trees and can survive on humidity without having to absorb water from the soil. The air plants sold in local neighborhoods are the best example of this. Most of them hang from trees, have no roots, and live by absorbing moisture from the air. The same is true for epiphytes. Ferns are the most common of these plants and exist by clinging tightly to trees. Instead of absorbing moisture from soil dampened by rain, these hot country plants grow from the humidity in the air, which makes them totally dependent on humidity to live.
So, how does a cactus survive in the desert when rain only comes once in several months and there is no humidity? As you may know, a cactus has spines that serve multiple purposes including protection from being eaten by animals and providing shade, but the spines actually have another important function. Fog in the desert is unique because of the extreme temperature differences. When it rises in the morning, the cacti collect moisture from the fog and gather it on the tip of their spines to yield a single drop of water on the plant stem, and the cacti survive by repeatedly collecting this single drop many times. In this way, the rainwater-dependent cacti use humidity to survive in the harsh environment of scarce moisture, proving once again that humidity is a very important factor for plants.
Important Things Learned While Traveling
Because my life's work is based on traveling, I travel the world viewing plants and natural environments, but the more I travel, the more that I realize the importance of appreciating the world that we inhabit. There are billions of commonplace settings and ways of life in the world, and this is the same for humans, plants, animals, and insects. In Japan, we may think it is only natural to wake up in the morning, put on our clothes, and take the train to work because that’s commonplace to us, but people in desert countries may start their day by waking up and thinking, "Where should I take my camels to eat weeds today?" That is what commonplace for them.
As a person born and raised in the natural environment of Japan, I have an innate concept for what is commonplace in nature based on my experience. However, when I learn and think about plants in cold countries, as in the previous article, or when I think about plants in hot countries, as in this article, that concept completely changes. What I have accepted as a commonplace no longer applies. Learning the natural characteristics of plants in other climates, we gain a sense of the unique seasons and the natural environments that we take for granted while living in our own countries and enables us to see things from a broader perspective. That leads us to having greater appreciation for the good things surrounding us and is probably the most interesting part of what I’m talking about in this series.
