Blade or lamina. The petioles grow with the blades in a peltate fashion

Дата канвертавання17.04.2016
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Colocasia esculenta information

Colocasia esculenta frequently grow up to 2 meters under ideal conditions, although some are capable of becoming larger. This height is based only off the petioles (the stem-like structures connecting the corm to the leaf (known as the blade or lamina)). The petioles grow with the blades in a peltate fashion (the ‘stem’ connects to the leaf somewhere in the center). The large leaves are often heart-shaped or arrow-shaped, growing up to 2 feet long under ideal conditions. There are several major veins that grow prominently on the bottom side of the leaf, forming a y-shaped pattern with branching veins (this is known as reticulate or ‘net-veined’). The front half of the

leaf curves in slightly, forming a concave bowl-like shape once the leaf begins to die off.

It is very typical for old leaves to die off in place of newer leaves (which, unfortunately, is very wasteful and sometimes warrant fertilizer use). While it is typically beneficial for dead parts of plants to be removed, the plant uses hydrolysis (a method of breaking down polymers into monomers) to break up nutrients. These nutrients are then transported to the “HQ” of the plant, where most of the nutrients are stored, known as the corm. The process of senescence, or as it commonly known as aging, allows for elephant ears to live quickly at the expense of dying young. The petioles turn in an attempt to reach sunlight if the plant has insufficient light (heliotropism is the main agent behind this movement). It is common for petioles to droop a bit during night in order to conserve energy.

Flowering in C. esculenta in rather rare (especially in areas where this type of plant cannot grow outdoors year-round). Inflorescences (clusters of flowers) grow up from either leaf axils (the area between the leaf and the top of the corm) or from a group of immature, unraveled leaves. A small peduncle (the stalk of an inflorescence of solitary flower), a spadix (a fleshy, bumpy ‘spike’ bearing tiny flowers that is usually protected by a spathe), and a spathe (a leaf-like bract (a usually small, leaf-like structure that tends to surround a flowering structure) that encloses the spadix) make up a single inflorescence. The spadix is around 6-14 centimeters in length, with female flowers at the base, male flowers around the edges, sterile flowers in between the two aforementioned, and no flowers at the extreme tip or ‘sterile appendage’. The sterile appendage differs in size depending on the type of C. esculenta, eddoe or dasheen. The spathe encompasses the entire spadix, connecting to it at the base before forming a concave shape as it goes higher. Although not excellently understood, it is believed that flies often pollinate C. esculenta plants. When fruit production begins, the fruit (in the form of tiny, 3-5 millimeter round berries) grows at the base of the spadix and contains many seeds. Each seed contains embryos (fertilized eggs further along in development than zygotes), endosperm (the nutritious tissues that are absorbed by the embryo they surround), and a hard testa (a thick outer coat of a seed).

As for the center of the plant, corms are responsible for storing energy and growth both above and below the soil. They are composed of the thick brownish periderm (the outer layers of woody roots and stems) and a starch-filled parenchyma (unspecialized plant tissue made of thin-walled cells with empty space in between them for air) inside the corm. Corms can also have auxiliary buds, which some leaves may grow from. The corm often sends out stolons (known as horizontal ‘runners’, strawberries reproduce asexually through this manner as well) to create ‘cormlets’ (genetically identical (asexually reproduced) ‘daughter’ corms). These daughter corms store energy in other areas under the soil, but they don’t begin notable growth until the older mother corm has passed away or until the cormlets have stored enough nutrients and energy. Often, these cormlets will produce a fibrous root system within the first meter of soil beneath the surface, just as the center corm has, once proper conditions have been met. It is vital to note that the entire underground section of this type of plant has cells with calcium oxalate crystals in bundles (known as idioblasts). These calcium oxalate crystals can cause major skin, tongue, and throat irritation if digested, unless the plant has been thoroughly cooked and cleaned.

While very popular in Pacific islands, southern oriental countries, western Africa, and many other areas, growing conditions must be tropical (or near tropical) year-round for successful yields. Temperatures can rarely, if ever, slip below 21 degrees Celsius (70 degrees Fahrenheit) for a plant to remain healthy (which means that taro are recommended solely as a low-land crop). Taro require between 1500-2000 millimeters (59-79 inches) of rain each year to grow prosperously. Taro prefer full sunlight, although they will thrive in partial shade under intense heat. Taro are extremely resilient to heavy soils and intense flooding, although fields will need to be occasionally aired to prevent poisoning or drowning). A pH of 5.5-6.5 (up to 7.0) is required for positive growth. Even under ideal conditions, it is uncommon for C. esculenta to flower. To alleviate this problem, researchers developed multiple solutions.

Gibberellic acid (GA) is an unusual chemical. Through a process known as “pro-gibbing”, where Gibberellic acid is applied to plants at different times in a plant’s life and at certain quantities, scientists have found a way to cause taro to flower. Once the taro flowers and is pollinated either by insects or manually, the researchers take the seeds from the spadix and place them in Petri dishes. Once the seeds germinate, they are moved to a very warm and humid greenhouse, where the plants will grow until they are ready to be planted in the field. Breeders pick the ‘best’ specimens (those with the most advantageous qualities) to carry on their genes to the next generation.  Alternatively, meristem culture can be used for genetically identical ‘cloning’. Meristem culture is a process where a microscopic tip meristem is extracted from a living plant, sterilized, and grown in a nutrient-rich Petri dish. The single meristem quickly creates tissues of callus (which is done because the plant automatically tries to block the wound from infection). Bits of the callus tissue can be used to subculture (cultivating individual types of cells) to create new plants which will give rise to leaves and a root system. This method is used to have genetically ‘elite’ plants grow in mass.

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