Bromeliad: Characteristics, Danger Of Extinction, Reproduction

Bromelia  is a genus of plants native to a tropical area of ​​the American continent called the Guiana Shield in Venezuela, belonging to the Bromeliaceae family. However, plants of other genera of the same Bromeliaceae family are commonly called bromeliad.

Plants of the genus Bromeliad are distinguished by having leathery, ribbon-shaped leaves of green and red color, showy panicle flowers, and berry-like fruit. The vast majority of bromeliads fulfill an important ecosystem function due to their ability to store water in a tank-like structure that they form with their leaves.

These water tanks represent an interesting mechanism of adaptation and survival of the plant and fulfill the function of providing a microhabitat for communities of plant and animal microorganisms (aquatic insects, spiders, mollusks, amphibians, small reptiles and small birds).

Classification

Depending on where they live, bromeliads can be classified into:

Terrestrial: if they grow on the ground,

Rupicoles or saxicoles: if they live on stones or rocks, and

Epiphytes: if they live on other plants.

Geographical distribution and habitat

The Bromeliaceae family is made up of approximately 3,170 species distributed in 58 genera, located in the American continent from the southern United States in Florida to Argentina, but mainly in Mexico, Belize, Guatemala, Panama, the Antilles, Venezuela, Colombia and a only existing species in West Africa, Pitcarnia feliciana.

Bromeliads are a genus with a large number of terrestrial and epiphytic species, which inhabit a warm tropical climate from 0 to 2,900 m above sea level, in coastal dunes and humid tropical forests.

These plants have managed to adapt to tropical rainforests, the peaks of the tepuis, the Andean highlands, xerophytic areas of the coasts of the Caribbean Sea and swamps of the American Florida.

Due to their high degree of endemism, bromeliads constitute one of the most important genera within their habitat, most commonly humid tropical forests.

Evolutionary origin

There are two theories about the origin of bromeliads. The most widely accepted affirms that in the Early Oligocene -stage in the geological evolution of the planet 33 million years ago, in which the continents had already separated-, a small group of plants, in the tepuis of Venezuela, began their diversification, dispersal and colonization in the American continent.

Tepuis

The tepuis (plural of Tepuy), are particularly steep plateaus, with vertical walls and practically flat peaks, located on the Guiana Shield, in southern Venezuela. They are the oldest exposed geological formations on the planet, originating in the Precambrian.

The word Tepuy comes from a word from the Pemón indigenous language, which means “mountain home to the gods.”

The tepuis do not form a chain but are isolated individually. Due to this isolation characteristic, the tepuis have very particular environments where unique plant and animal life forms develop.

Morphological characteristics

The genus Bromelia was initially described by Carolus Linnaeus, Swedish botanist and zoologist (1707-1778), creator of the classification of living beings (taxonomy). The name Bromeliad was assigned in honor of the Swedish botanist Olof Bromelius (1639-1705).

The species belonging to the genus Bromelia are bushy plants with a certain structural complexity and persistence of habitat.

Below is a simplified general morphological description of the plants of the genus Bromeliad .

Root

In epiphytic bromeliads (which live on other plants) and rupicolous (live on rocks), the rhizome or stoloniferous roots are small and must have the maximum capacity to grip their substrates different from the soil.

Stem

They are acaulescent (stemless) or slightly caulescent (short stem) plants. This phenomenon is called vegetative reduction.

Leaves

Bromeliads have long, narrow, ribbon-shaped leaves that are bright green and red, leathery. The leaf margin is serrated, the edge has thorns.

The leaves are numerous, erect, and in the vast majority of bromeliads, they are arranged very tightly, overlapping in the form of a rosette.

This fact allows them to have an almost unique morphological characteristic of the Bromeliaceae family: the development of a tank-like structure (fitotelmata), where rainwater and organic matter are collected , which creates a habitat for microorganisms, insects, arachnids, mollusks, amphibians, in addition to serving as food for small reptiles and birds.

flowers

Bromeliad flowers have fleshy petals, they grow in groups, on a short axis or panicle. They are very attractive flowers to look at. The inflorescences vary greatly in shape, size, and color.

Fruit

Berry-like fruits, of various colors, yellow or pink, fleshy and with flattened seeds.

Ecophysiological characteristics

Adaptive radiation

Bromeliads are said to be successful plants for having survived and colonizing many different areas of America. This success is explained by its high adaptability.

Adaptive radiation is a process of biological evolution that describes the rapid speciation of one or more species, filling available ecological niches. The tops of the tepuis are places with very adverse conditions for the development of plants.

The precipitations are abundant, the rocky soil does not allow infiltration or retain water. The solar irradiation is very intense (since the Guiana Shield is crossed by the Earth’s equatorial line) and the fluctuation in temperature between day and night is very high.

The plants that grow in the tepuis must be able to develop in environments that are poor in nutrients, high solar irradiation and humidity, but low availability of soil water. For these reasons there are large areas devoid of vegetation in the tepuis.

Adaptation mechanisms

Bromeliads overcome all these difficulties that the vast majority of plants cannot overcome, through the following adaptation mechanisms.

Existence of specialized trichomes

Trichomes are epidermal appendage structures, in the form of papillae, hairs or scales. They can serve as protection from ultraviolet radiation. In addition, they secrete substances that serve as defense against predators, attract pollinators, are antibacterial or antifungal.

In epiphytic plants of the genus Bromelia , the trichomes of the leaves have the important function of absorbing water and nutrients from the phytotelm. In some tankless bromeliads, the greyish trichomes absorb moisture and nutrients and protect from excessive tropical solar radiation by reflecting incident light (eg, bromeliads of the genus Tillandsia) .

Fitotelmata

The fitotelmata are constituted by the set of bodies or reservoirs of water in non-aquatic plants. They are formed in structures such as modified leaves, foliar axils, flowers, perforated internodes, cavities in the trunks, among others.

The genus Bromelia has a large number of fitotelmata species, which trap water in a central tank and / or in the foliar axils. These small bodies of water can function as microhabitats for a wide variety of aquatic organisms.

In this way, through their fitotelmata water tanks, a good part of the bromeliads offers ideal conditions of humidity, temperature, food and protective shelter against predators, supporting complex communities of associated organisms.

Among these are algae, bacteria, fungi, microscopic unicellular animals, small crustaceans, spiders, aquatic insects, mollusks, nematodes, frogs, lizards, iguanas, among others.

The advantages of having water tanks for species of the Bromeliad genus are the availability and reserve not only of water, but of nutrients such as simple chemical compounds already degraded by decomposers (bacteria and fungi), which live in the phytotelma and which they are absorbed by the foliar trichomes directly.

Terrariums in bromeliads

The foliar axils of many species of bromeliads do not retain water but are humid places with decomposing organic material.

These axillary places transform into terrarium microhabitats that provide shelter for small land animals such as scorpions, worms, snakes, and assorted reptiles.

CAM metabolism

The acid metabolism of Crassulaceae or CAM (from the English: Crassulaceae Acid Metabolism), is a special type of metabolism that some plants present.

Most plants absorb and fix CO 2 during the day. In plants with CAM metabolism, these two processes – absorption of CO 2 and its fixation in organic carbohydrate compounds – occur separately in two phases.

In CAM metabolism, the CO 2 required for photosynthesis is absorbed overnight and stored in cellular vacuoles as malic acid. The next day, the CO is released from the malic acid and used in the production of carbohydrates mediated by sunlight.

This mechanism allows the adaptive advantage of saving water, since during the daytime hours of greater solar irradiation and maximum temperatures, plants can keep their stomata closed and therefore can minimize the loss of water through perspiration.

Reproductive adaptations

Plants of the genus Bromelia have two mechanisms of reproduction, one sexual and the other asexual.

Sexual reproduction

Sexual reproduction carried out through flowers and sexual gametes is an ineffective process in bromeliads, since their flowering occurs in periods of 2 to 10, 20 and up to 30 years, and there is the possibility that the plant will die before reproducing.

To compensate for this apparent disadvantage, bromeliads have several mechanisms that function as attractors for pollinating agents, which are generally hummingbirds and insects.

Synchronized with the hummingbirds’ most active and foraging stages, bromeliads secrete a more concentrated and attractive nectar.

After the stage of greatest activity of hummingbirds, part of this nectar descends through the axis that supports the flowers and functions as an insect attractor.

Through these mechanisms, the plant promotes an increase in the number of pollinators and cross-pollination or transport of pollen from one plant to another is guaranteed.

Asexual reproduction

Asexual reproduction occurs through vegetative forms such as daughter plants, leaves, or other plant parts.

The daughter plants are exact replicas of the adult parent plant (clones), which it can produce. Relative plants produce daughter plants in varying numbers just after flowering.

When the children or leaves of the plants fall on a substrate, they produce roots, fix themselves and grow, developing another plant with the same genetic load as the relative plant. The daughter plants grow in the same place where the relative plant has grown, with a very high probability of survival.

These two reproductive mechanisms of bromeliads are reinforced and lead to a successful outcome.

Associations with animals

The type of fauna associated with bromeliads depends on the degree of exposure to land and aerial predators, extreme environmental factors such as strong winds or intense solar radiation, among others.

The bromeliads that grow in the middle canopy (2 to 4 m high above the baseline), are those that offer the best living conditions for amphibians and reptiles.

Myrmecophilia

The term myrmecophilia literally means “love for ants” and refers to mutualistic associations with ants. There is a close relationship between bromeliads and ants.

Bromeliads provide a safe habitat and food for ants; the ants defend their place of establishment energetically, but additionally their waste – feces and dead ants – dumped in the water tank, serve as nutrients for the plant.

Danger of extinction

Several researchers have reported the danger of extinction to which bromeliads are exposed. This is because most of these plants are epiphytes and grow on trees, many times they are considered invasive parasitic weeds and are exterminated by farmers and gardeners.

We have already seen that epiphytic bromeliads only use trees as a point of support and support; its roots do not have nutrient and water absorption functions. They are not parasitic plants.

The destruction of bromeliad habitats, such as coastal mangroves and tropical cloud forests, due to deforestation, logging and mega mining, and the indiscriminate use without conservation measures, of their flowers, leaves and the entire plant as ornamental, causes the extinction of these plants .

Care for its cultivation

Bromeliads should be grown on tree trunks with medium sun exposure and their tank should be kept full of water. The temperature should fluctuate between 20 to 35 degrees Celsius, depending on the particular species.

Very dilute solutions of compost, nutrient salts and algae can be added to the tank, but growing outdoors generally does not require much care.

In addition to animal detritus, the fall of leaves, twigs and other plant parts from the upper canopy in the water tank, produces enough nutrients for the plant.

References

  1. Armbruster, P., Hutchison, RA and Cotgreave, P. (2002). Factors influencing community structure in South America tank bromeliad fauna. Oikos . 96: 225-234. doi: 10.1034 / j.1600-0706.2002.960204.x
  2. Dejean, A., Petitclerc, F., Azémar, F., Pelozuelo, L., Talaga, S., Leponce, M. and Compin, A. (2017). Aquatic life in neotropical rain forest canopies: Techniques using artificial phytotelmata to study invertebrate communities. Rendus Biologies . 341 (1): 20-27. doi: 10.1016 / j.cvri.2017.10.003
  3. Dejean, A., Talaga, S. and Cereghino, R. (2018), Tank bromeliad sustain high secondary production in neotropical forests. Aquatic Sciences . 80 (2). doi: 10.1007 / s00027-018-0566-3
  4. Frank, JH and Lounibos, LP (2009). Insects and allies associated with bromeliads: a review. Terrestrial Arthropod Reviews . 1 (2): 125-153. doi: 10.1163 / 18748308X414742
  5. Hietz, P., Ausserer, J. and Schindler, G. (2002). Growth, maturation and survival of epiphytic bromeliads in a Mexican cloud forest. Journal of Tropical Ecology . 18 (2): 177-191. doi: 10.1017 / S0266467402002122
  6. Texeira de Paula J., A., Figueira Araujo, B., Jabour, V., Gama Alves, R. and Campo Divino, A. (2017). Aquatic invertebrates associated with bromeliads in Atlantic Forests fragments. Biota Neotrop . 17 (1): 1-7. doi: 10.1590 / 1676-0611-bn-2016-0188
  7. Wagner, K. and Zotz, G. (2018). Epiphytic bromeliads in a changing world: The effect of elevated CO 2 and varying water supply on growth and nutrient relations. Plant Biology J. 20: 636-640. doi: 10.1111 / plb.12708

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