Answers and reviews about Biological characteristics of orchids

The Orchids is a sub-family (dermis) that hangs on other trees. Lean wood types are long, short, fat or slender, which take the body away or cluster into thick dust.

Scientific Name: Orchid sp.
Orchid family: Orchidaceac
Orchid set: Orchidales
Monocotyledoneac layer
Biological characteristics of orchids

1.1. Root orchid

The orchid family includes herbaceous plants, perennial, living in the soil, cliffs or secondary, decaying ...

When living in the soil, they often have fake tubers, have plump and luxuriant roots or have long or short root legs. However, the uniqueness of the orchid family is its attached lifestyle, suspended from the trunk of other trees. Orchids develop long, short, fat or slender rhizomes (depending on the species) that move the body away or cluster into thick bushes. The more or less developed the root system depends on the general shape of the body. Many orchid species are very small, ugly in shape, difficult to get them in the cracks of the bark of the tree, on the branches and branches. The root system is also small, woven into tufts, in contrast, in orchids with large or medium sizes, the pneumatophores develop in abundance, grow very long, fat, strong and keep the body from being blown away by the wind. swing, just make a support column for the body to rise high.

To absorb nutrients, they are surrounded by a thick, moist absorbent tissue, including layers of dead cells filled with air. With that spongy tissue layer, the roots are not only able to absorb rainwater running along the bark, but also get water suspended in the air (morning mist or steam).

Many species have intertwined, intertwined root systems that collect humus as a source of nutrients for plants. In contrast, there are species that grow long, the root system sometimes dangling down along the stem segments, hard or slender, suspended in the air extending to the ground and root-destroying activities of other plants. In some orchids with stems, leaves are underdeveloped (even completely reduced), the root system develops dense and concurrently plays the role of photosynthesis. The roots are flattened, crawling very long, green like leaves.

Especially, the saprophytic orchids, the root system has a unique shape and structure. It is in the form of a small bundle with short, dense suction nozzles that extract nutrients from the clumps of plant matter through the action of fungi. However, there are a few species that live decaying, but the tree can be several tens of meters long, it is capable of climbing and crawling very high.

1.2. Body (practitioner)

- Lan has 2 types of body: multi-body and single.

- In the secondary orchid species, there are many large bulges to form fake bulbs (practitioners). It is the part that stores water and nutrients to feed plants in drought conditions while living on high altitude.

- The tuber is very diverse: Spherical or oblong shapes stacked together or regularly scattered or cylindrical stacked into a fake body.

- Structure of fake tubers: Including many soft tissues filled with mucus, the outer layer is the epidermis with thick, smooth, protective cell walls, avoiding water loss due to hot sun. Most of the fake bulbs are shiny green, so with the leaves they act as photosynthesis.

Stems are short or elongated, sometimes branched, leaf-bearing or non-leafy. According to M.E. Pfizer (1882) (cited by Tran Hop, 1990), orchids have 2 types of stem, most of them belong to axial growth type (non-stem group). This body consists of a system of many perennial branches, with horizontal parts, crawling on the base or hidden deep in the ground, called the rhizome. Conversely, very rare species of orchids that grow unicorn (group with stems) means the growth of the spindle is not limited, making the body very long, the body is difficult to maintain a straight posture. Standing, it has to rely on the supporting roots to rise, otherwise, it will have to crawl or climb. Sometimes the stems of some orchid species are very short, obscured by a dense bushing of leaves or roots.

In the secondary orchid species, there are many large phlegmon segments, forming fake bulbs (onions). It is the part that stores water and nutrients to feed plants in drought conditions while living on high altitude. The bulbs are varied, either spherical, oblong, spaced or scattered, regular (Bulbophylum) or cylindrical, piled up into a pseudomembrane (Dendrobium). The size of fake bulbs is also very variable, from a very small bulb that is only as large as the bulb's head (Bulbophylum) to the size of an adult hat (Peristeria elata). Most fake bulbs are glossy green, so along with the leaves it also acts as photosynthesis.

1.3. Orchid leaf

Most orchids are autotrophs, so they fully develop a leaf system that is soft, graceful and attractive. Leaves grow solitary, or dense at the base, or regularly arranged on stems, on fake tubers. Leaf shape varies greatly, from succulent leaves, lean, needle-long, long cylindrical, rounded or grooved, to thin, long glossy, dark or light green leaves depending on location. The life of the tree, especially very rare, the leaves are round, oblong and elongate to hug the stem. The leaf blade spreads or folds along the arched veins (such as a fan or just folds along the midrib, V-shaped), the lower leaves close to the base are usually reduced to only the sheaths without blade or completely reduced to scales.

In terms of color, the leaf blade is usually shiny green, but sometimes the two sides have different colors, the lower surface of the leaf is dark green or purple, the upper side of the leaf is mosaic more colorful. Many orchids have pink leaves and embossed white lines in beautiful veins.

Orchids, especially in the tropics, often shed their leaves during the dry season. At this time, the tree will flower or live in hiding, wait for the rainy season to come to give new buds. Some orchids that live in the soil have a very special life cycle, alternating the leaf season with the flower season. When the plant is flowering, all the leaves will die and when the flowers die, the fake tubers will give new buds and leaves.

The structure of the orchid is extremely rich and attractive. We can encounter many species that each season only one flower or there are many clusters of flowers that each cluster only blooms, but most orchids are blooming with many flowers, gathered in clusters (sometimes branching into cycle) distributed in the apical or axillary leaves.

Although there are many shapes and variations, if we observe the general flower of any orchid, there is a homogeneous organization of flower pattern 3 which is a typical flower type of the single-cotyledon layer, but has changed. very much so that the flower is symmetrical across a plane. Outside there are 6 petals, in which 3 outer petals are called 3 sepals, usually with the same color and same size, one sepals located on the top or back of the flower is called sepals. the other two wings are located on either side called the side sepals or the side sepals. The three sepals should be small and green like other flowers, but in orchids they are large and colored, the same size as the petals. Located next to the inside and interspersed with 3 sepals are 2 petals, usually the same in shape, size and color, so it is called 2 side petals, the other one is above or below the flower. often have a distinctive color and shape that differs from the other two, called the lip wing or tongue wing. It is the lips that determine most of the aesthetic value of the orchid.

In the middle of the flower there is a prominent pillar, which is the genitals of the flower, helping to maintain the strain of the orchid plant. That column includes both male and female genitals, so it is called the axis - the stigma. The male part is located on the upper part of the shaft, usually with a cover, the inside contains yellow chalk, the amount of chalk ranging from 2,4,6 to 8 is oblong or crescent, sometimes elongated. , with tail. The chalk mass is caused by many sticky pollen grains. The number, shape and size of chalk mass varies depending on the variety and species of orchid.

Orchids have lower gourd, elongate along the stalk (it is difficult to distinguish between gourd and flower stalk). The twisting of the whole flower during growing is a characteristic of the gourd. Flowers are often twisted 1800 so that the lip when the flower begins to bloom, facing the outside, at the bottom, makes a favorable place for insects. Very rarely see 3600 twisted flowers like Malaxia, Paludosa or do not turn anything because the flower stalks down like Stanhopea, when the flower blooms, the lips are pointed upwards, it adapts to insects that like to turn their heads down when entering the flower. .

The orchid gourd has 3 cells called the 3 centers or mesoderm (in primitive orchids) or attached to the lateral ovule in more evolved orchids. In the bulb contains a multitude of tiny particles called oocyte located on 3 lines, along the length of the 3 margins of the dermis. After fertilization, the oocytes will change and develop into seeds, while the large ovule will develop into fruit.

1.4. flower

- The flowers are symmetrical over a plane.

Outside, there are 6 petals, of which the outer 3 are 3 sepals, usually of the same color and size. A sepals located above or behind the flower are called sepals, two sides are called sepals next. Located next to the inside and interspersed with 3 sepals are 3 petals, they are similar in shape, size and color. The other wing is located above or below, having a different shape and color from the other wings called the lip. The lip determines the aesthetic value of orchids.

- In the middle of the flower there is a prominent pillar, which is the genitals of the plant, helping the plant to maintain the race. Head consists of stamens and stamens. After pollination, the petals wilt and flower stalks form an orchid.

1.5. Fruit and seeds

- The orchid is a capsule, which blooms in 3-6 longitudinal fissures, ranging from a long radish (Vanilla) to a short, bulging cylinder in the middle (in most other species). When ripe, the fruit expands and the remaining peels stick together at the top and base. In some species, the ripe fruit blooms in 1-2 longitudinal grooves, not even cracking, but the seeds only come out of the pod when the bark is rotted.

- The seeds are a lot, tiny (hence the orchid family is called the horoscope family). Particles are made up of an undifferentiated mass, on a small, porous, air-filled network. It takes 2 - 18 months to ripen seeds. Most seeds usually die because the symbiotic fungus needed to germinate is difficult to find. So a lot of seeds can travel very far in the wind, but it is very rare to germinate into a tree. Only in wet old forests, the tropics are eligible for orchid seeds to sprout. The mass of all seeds in one fruit is only 1/10 to 1/1000 milligrams. In which the air accounts for about 76 - 96% of the volume of the particle. Apparently, the orchid seeds have almost no mass.