Ensuring sufficient food for its growing population is a major challenge faced by humanity. An additional challenge is the increasing need for diverse plant products for fuel, fibers and chemicals. Plants sustain the life on Earth. They are the basis for terrestrial ecosystems, have a profound impact on atmospheric chemistry, and support other organisms by using sunlight to convert water and carbon dioxide into organic matter.
Plants live just about everywhere on Earth. Adaptations were evolved to allow them to survive and reproduce under a diversity of conditions. They have overcome many challenges during the whole period of evolution.
All plants regardless of habitat they live, share common needs. They are Sunlight, Water, Air and Nutrients. All growing plants face the challenge of obtaining adequate amount of those needs for their optimum growth.
Tropical climate is a real challenge faced by growing plants which cause lack of proper amount of sunlight due to thick canopy, water logging and nutrient lacking soil due to nutrient fixation by large plants. They have overcome deficiency of sunlight by evolving different leaf arrangements which helps maximum exposure to available sunlight. They also have very dark green leaves with high density of chlorophyll for maximum utilization of sunlight. In addition some plants show aerial growth on forms of epiphytes, lianas and creepers such that they receive more sunlight than ground plants.
Most tropical plants have slick waxy cuticle to allow rain to run off. Since soil is very moist shallow roots are present. Buttress roots or stilt roots keep stability in loose soil. To overcome lack of available nutrients most of tropical plants show symbiosis with nitrogen fixing bacteria.
In contrast to tropical climates, desert and dry climates shows excess of sunlight and lack of water for optimum plant growth. Due to excess sunlight plant face many challenges like evaporation of water, bleaching of chlorophylls, increased temperature etc. Sandy soil makes it very difficult for water availability.
In order to overcome these challenges these plants have reduced leaves or modified leaves into thorns. Instead they have thick, fleshy and green “accordion” stem with sunken stomata. It involves in photosynthesis and water storage and prevent water loss. Plants are covered with thick waxy cuticles which reduce evaporation and also reflect sunlight. Their prominent feature is succulent which allows storing water in specialized tissues. In addition they have an extensive root system which runs deep into the ground in order to absorb as much as water available.
Unlike both Tropical plants and Desert plants, Temperate plants face a completely different problem during their growth. That is seasonal changes. Due to shifting of seasons drastic changes in temperature, humidity, water content and sunlight availability takes place. These directly affect the growth of plants.
As adaptation to temperate climate, most plants have adopted an annual life cycle. If perennial they show deciduousness or else leaves show needle shape protected by thick cuticle. Also a thick bark is a characteristic of temperate plants to survive harsh winters. These plants also have developed dormancy in seeds in order to continue growth in most favorable weather conditions.
In addition to above mention challenges and adaptations for them, some plants show very unique and specific adaptations against particular challenges faced by them. As an example some plants which live in Nitrogen deficient soils have adapted to become carnivorous. They capture small insects to satisfy their Nitrogen requirements.
Similarly aquatic plants face challenges like lack of sunlight and air. Thus those plants are usually consist of stems with airy spaces inside. Water repellent nature on leaf surface and roots attached to ground against water current are another few mechanisms they have adopted.
On the other hand all the plants consider fertilization, pollination, dispersion and germination as challenges irrespective to the environmental conditions they live in. Hence they develop many mechanisms to ensure maximum, efficient and proper reproduction. Adaptations for cross pollination instead of self-pollination using various pollinating agents is one such mechanism. Plants have developed some surprising adaptations to attract animals as pollinating agents, such as nectar, colorful flowers, scent and mimcry etc. Also dispersal methods like covering of seeds with edible fruits, floating mechanisms for water as well as air are some other adaptations.
Some plants show adaptations against the challenges of various environmental threats and predators. Showing mimicry and developing defense mechanisms like poisons and sharp spines are such mechanisms.
Plants don’t have an immune systems. However they do respond to diseases. Usually, the death of cells surrounding infected tissue is their first line of defense and prevent spreading of the infection. Many plants produce hormones as well as toxins to fight pathogens. Willow trees producing salicylic acid to kill bacteria is a good example in that regard. Thus many acne products use same compound. As suggested by exciting new research plants may even produce chemicals that warn other plants of threats to their health, allowing them to prepare for their own defense.
As proven from these, plants may be rooted in one place, but they are far from helpless. They swim against the up current and have overcome major challenge of surviving they have been provided with. Hence plants have able to survive many eons on earth. They will continue to thrive unless mankind rend them helpless and let them doom.
Image Courtesy :
- Title Image : https://bit.ly/2Ne9ozw
- 1st Content Image : https://bit.ly/2sc7wzY
- 2nd Content Image : https://bit.ly/2NeIEiy
- 3rd Content Image : https://www.flickr.com/photos/nico_bees_wasps/5810854825