Coffee Plant Botany

Class: Dicotyledoneae
Subclass: Sympetalae or Metachlamydeae
Order: Rubiales
Family: Rubiaceae
Genus: Coffea
Species: Coffea Arabica, Coffea Robusta

Coffea Robusta, left, is a shrub type plant. The Robusta coffee plant grows similar to a bush, in that it has several trunks. Although, the coffee plant may have one trunk, it tends to have more. Additionally, this characteristic of trunking is different among the various coffee species. Coffea Arabica, right, is a tree type plant. The Arabica coffee plant drives a straight up trunk with branches paired off outward and lower branches tend to drupe downward.

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	Coffee Leaf Kind: abrupilypinnate. It is a bipolar leaf structure, where two leafs grow from the stem opposite each other. The distance between leaf pairs an the stem is about 1 to 3 inches. The leaf pairs generally are at 90 degree rotation for each pair on the stem. It is an evergreen.
		Coffee Leaf Margin: entire - undulate. The edges of the leaf have a ripply look to them. However, younger plants have an even edge look to them. This varies among types.
		Coffee Leaf Shape: oblong - ovate. Typically, the plant types are more ovate than oblong. This varies among types.
	Coffee Leaf Base: acuminate. This characteristic is fairly common among types.

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	Coffee Leaf Tip: acuminate. This also is pretty much common among types.
	Coffee Leaf Venation: midrib to margin. This varies among types.

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	3 by 6 inch leaf. Typical Lengths: 4 to 6 inches.
	Typical Widths: 1 to 3 inches. Color: is a deep green with a waxy surface.
	The flower is white, are produced in dense clusters, and formed in the axils of the leaves. (Where the leaf protrudes from the stem.)
	The flowers have five-toothed calyx (outer wall of the flower), a tubular five-parted corolla (inner wall of the flower).
	Five stamens (pollen bearing organ) and a single bifid style (one piece pointed and divided in two equal parts). The flowers last only a few days. The plan blooms shortly after a rain. The flower has a strong pleasing smell. Also different for each plant type.	Sexually, the Coffea arabica is autogamous, in that it can pollinate itself, where as the Coffea Robusta can not pollinate itself.
	After pollination, a small green berry appears called a drupe. This berry grows to about 15-35 millimeters (0.5 inch to 1.25 inches) depending on species. The berry grows in clusters. When the berry is ripe it turns red. At maturity, the berry is bright red. After what is considered ripe, the berry turns brown to reddish brown and falls off the tree. Many growers allow the berry to fall to the ground, but most pick it when it is red.

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Like a walnut, there are typically two seeds per berry packed with the flat end facing each other, but that is not always the case. A special case which is common is called peaberry which is a single seed. But, there can be more than two in a berry also.   The outer skin is generally tough and can withstand handling. The inner pulp is generally mushy. In a few types of coffee plants, the pulp is more valuable than the bean itself. This is because the pulp has a high sugar content and can be fermented. The parchment is fairly tough. This is taken off in the last processing stage. However, the silverskin is so thin and attached so well it tends to stay with the bean right up to roasting. When roasted, the silverskin can, and usually does, crack off. The silverskin cracks off because it does not expand like the inner bean does when roasted. This posses a problem in two ways. First it is a thin messy chaff which is undesirable and must be removed from the batch of roasted beans for cosmetic reasons. Second, it can easily catch fire.

Cultivation

Cultivation of the coffee plant over a period of several hundred years has brought about considerable variations to grow in various types of climate and soil conditions. The color and chemical content of the "green bean" typically reflects these different types of the coffee plants.

Typically, the geography of the coffee plant is in a tropical 25 degree latitude belt on both sides of the equator. The Arabica coffee plant grows best at altitudes between 3000 and 6000 feet. Coffee plants can be grown at lower altitude but attack from various parasites cause problems which make low altitude cultivation hard.

Desirable temperature averages between 65 to 75 degrees Fahrenheit. The Arabica coffee plant will grow in hotter areas but is not well suited for higher temperature. The Robusta coffee plant is typically located in hotter and more humid areas at lower altitudes around 600 to 1500 feet. Frost will kill every variety of coffee plant known. Such freezing temperatures only takes minutes to start killing the coffee plant too. Thus, it limits the altitude which this plant can thrive and the latitude. The coffee plant is susceptible to changes in temperature. Temperature affects the color of the leaf, the hotter the lighter the color green. The longer periods of deep green, the healthier the coffee plant.

Generally, the coffee growing area takes at least 75 inches per year. The rainfall should be spread over a 9 month period, with about 2-3 months of only a few inches of rain. The dry spell is needed to allow buds, flowering, and new growth. Erosion aside, the coffee plant will grow well with much more water so long as it does not sit in water. In areas with less than 75 inches per year, careful irrigation will provide adequate water.

The soil should be humus, generally porous, and a slight tendency toward acid but more or less a neutral pH. Coffee plants can grow in slightly base soil. But too much acid or base will kill the coffee plant. Additionally, there is a preference for pH which depends on the type of coffee plant. Mulching the surface with grass, compost, or vegetable refuse is desirable. Preferably it should be a soil that is heavy to work and not too loose and sandy. Very generally speaking, the planting conditions of the coffee plant are similar as for a camellia. The coffee plant doesn't like hard pack soil or sitting in water for long periods of time. The subsoil should stay moist but not soggy as to promote rot. The roots breath and actually need some air. Thus, constant water cause the leaves to turn yellow, young shoots wilt, and the tree dies.

The coffee plant likes humidity of about 90 percent. The humidity in the air performs two functions, one is to keep evaporation from the plant at a minimum, the other is to diffuse the light. Humidity is microscopically small water droplets in the air. These droplets lightly disperse the light. Again, this varies with the type of coffee plant.

Coffee plants like filtered to moderate lighting. Coffee grows on sides of mountains best which it is said makes for natural partial lighting conditions. However, many types of coffee plants can take direct sun light without overhead shade trees or a mountain cutting off a half days light. And again, this differs with coffee plant types. There are four kinds of shade; temporary, permanent, forest, and soil shade. Bare soil loses its richness and character by being baked by the sun and beat on by the rain. If the sun bakes the top soil too much, the roots die. Therefore, for most coffee plants, the soil should be shaded as much as possible. Both mulch and the way the coffee plant is cropped accomplish this task. In some places cover crops as Leucaena glauca are planted between the coffee trees to keep the soil in good shape. Depending on plant, the leaves may need shade too. The coffee plant generally requires direct sun light for a portion of the day, so absolute permanent shade is not a good practice. Forest shade has a problem with the type of plants surrounding the coffee tree. The wrong type of forest plants can take nutrients from the soil or actually strangle the coffee plant. On the other hand, the nature of the shade is ok.

The coffee plant does not take well to wind either. Wind dries the leaves out too quickly. A cold wind is one where the air is cooled by low temperatures and snow in the distant mountains. If a chill hits the coffee plant, it starts dying right a way. Additionally, windy areas bring in grasses and weeds from a distance. The plant does not do well if surrounded by the wrong type of grass or weed. The plant really doesn't take a joke when it comes to chemical grass and weed killers. Consequently, the drying effect, quick temperature changes, and the transportation of unwanted seeds makes windy conditions undesirable.

Typically, the coffee plant can produce berries for about 60 years but most commercial coffee operations limit the life of the coffee plant to about 20 years. Some coffee growers feel earlier termination is appropriate. Although the coffee tree produces berries at the age of 3, it starts producing at about 5 years old.

The two basic propagation methods both work with the coffee plant, grown from seeds, or cloned from cuttings. Seeds take about 5 to 6 weeks to germinate. Tender shoots require more shade. Generally, the cuttings, or seedlings are nurtured in a nursery before being planted in the field. A general rule of thumb is plant the seedling when it has more than four and less than eight branch pairs, which tends to be 5 to 6 months. Coffee plants can be grafted. Grafting tends to adapt a plant for growing conditions and disease resistance. The coffee plant has been worked over almost as much as dogs and cats, so grafting is not as important as choosing the right subspecies. It should be noted that the coffee seed will not remain fertile for long periods of time. Due to the pulpy nature of the berry, the seed either starts to germinate when it is removed from the tree or it ferments. The coffee bean, after being removed from the berry can grow but has sever problems.

Coffee growers refer to pruning as training. Exactly how the plant is trained depends on the type of plant, the environment, and the labor. The branches can become so heavy with berries that they break, so it is important to train the plant such that it is strong enough. From time to time, the coffee plant gets too large of root system for the soil conditions or the middle lateral branches become damaged, so the plant is trunked. Trunking the plant is cutting it way back, right down to where only two branches near the bottom are left on it. These branches are shorten to where only the nearest to the trunk leafed section is left. On good reason two branches are left is because one may not make it and it the second branch hopefully will.

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DISEASES

The coffee plant is very prone to weather conditions, deceases and attack from parasites. The Robusta plant being better adapted to resist such attacks which is how it got it's name "Robust." The Mediterranean fruit fly is a serious problem. The stephanodores leaf-miner is referred to as the coffee-plague. The Hemileia Vastatrix has destroyed the whole know world's crops, and can easily wipe out a plantation.

A note from one who is not a botanist. Plants do not take their nutrients from the soil. No plant takes it's nutrients from the soil. Plants get their nutrients form the fungus in the soil. Thus, although the plant looks as though it is getting it's nutrients from fertilization, it actually is not. The fungus is getting it's food from fertilization and the plant is getting it's food from the fungus. Interesting!

The point being, funguses are very susceptible to attack from other funguses. Since funguses are microscopically small and proliferous, they can be found on everything including nuclear power plant plutonium rods. They can be carried easily by accident without anyone being aware of their presence. Since coffee is shipped around the world, worldly people travel to coffee producing areas, it is easy to transfer a fungus. Thus, it is possible that attacking funguses can be imported easily. Such was the case with Hemileia Vastatrix. Around 1870's the Hemileia Vastatrix wiped out a whole hemisphere of coffee crops. Additionally, it is very difficult to eradicate a fungus.

Due to the ease which funguses travel, it is no wonder why these paranoid plantation owners guard their crops with guns. How do you stop something you can't see?

Worse yet, every coffee plantation has a disease problem all the time. Diseases can be sever, mild, attack only part of the plant, or all the plant. Some types of coffee plants a predisposed to some types of diseases. Healthy plants, like healthy humans resist diseases, conversely, unhealthy plants, like unhealthy humans are much more susceptible to diseases. A coffee grower must be aware of the diseases and take immediate defensive action when one shows itself. Everyone who works in the field is usually trained in spotting diseases. Because coffee disease spread easily, coffee growers commonly bond together in associations to defend the crop.

Generally speaking, the coffee plant is very fragile and can't take a joke.