Learning about coffee

The growth of the branches is possible due to the action of the buds, which are regions consisting of cells that haven’t differentiated themselves yet and that, by means of hormonal stimuli, form the vegetative and reproductive structures of the plants.

The apical bud, located at the apex of the branch, is responsible for the vertical growth of the plant, called the main stem or orthotropic branch.

The side buds, located in the leaf axils of the orthotropic branch, will differentiate into leaves and mainly, into plagiotropic branches - which emerge from the stem and grow laterally.

The buds, usually five to six in number, are called series, and the first bud of the set is called head of series. The head of series buds will mainly originate plagiotropic branches.

When they are on the orthotropic branches, these buds will originate "naked neck" branches, which are the result of plants that are poorly managed after pruning or lack of pruning. These branches will compete with the natural branches for the products of photosynthesis.

Coffee trees are shrubs of continuous growth and reach a height of 2 to 4 meters, depending on the weather conditions of the region. The stem is the main orthotropic branch, which is cylindrical and can generate two types of branches: other orthotropic and plagiotropic branches.

In the stem, vessels called xylem carry the raw sap - composed of water and mineral salts absorbed from the soil - and vessels called phloem carry the elaborate sap - composed of water and products of photosynthesis performed in the leaves - towards the rest of the plant

They are present on the plagiotropic branches and are responsible for photosynthesis. The epidermis, or outer layer, is covered by a cuticle that reduces water loss.

They also contain a great diversity of cells, such as the stomata, which are responsible for the plant's gas exchange and transpiration.

The coffee tree’s root system is formed by a poorly developed pivotal root, a characteristic of the seedling formation system, because at the time of planting in the field, the seedling’s container is cut and consequently, so is the main root.

The root is the part where the most intense exchange of substances occurs between the plant, microorganisms, and inorganic particles. It is critical for the absorption of water and for the fixation of the plant in the place where it’s developing. 

The buds that will become flowers go through an induction process, which is characterized by stimuli that signal the plant to change its development program.

After induction, the differentiated buds go through a dry spell during autumn-winter, leaving the buds dormant. Between 7 and 15 days after the first spring rain, it resumes its development.

Após a indução, as gemas diferenciadas passam por um período de seca no outono-inverno, deixando os botões dormentes. De 7 a 15 dias depois da primeira chuva da primavera, ela retoma o seu desenvolvimento.

At this time, the water and temperature are ideal for the vegetative growth and fructification of the coffee tree.

The flowers are pentamerous and white in color. When the flowers open, more than 90% have already been self fecundated, because it’s hermaphrodite, i.e., it has both sexual organs, its male part will fecundate the female part.

The flower is composed of the androecium, where the male gametes are produced, and the female gametes are called gynoecium.

The anthers, belonging to the androecium, will produce the pollen grain that will fertilize the ovule.  

Another pollen grain will fertilize the polar nuclei, located inside the female gamete as well, forming the endosperm that will feed the embryo until it finds suitable conditions to germinate.

Because they have already been fertilized, the flowers have a very short lifespan. A few hours after opening, the petals begin to dehydrate, wither, and dry up.

The next day, the flower detaches itself from the plant and falls, leaving behind the fertilized ovary that will result in a fruit, usually taking about seven months to ripen and ready to be harvested, and are called cherries.

The fruit is composed of three layers until it reaches the seed:
 - Exocarp: corresponds to the fruit's shell, which is red or yellow when ripe, depending on the species.
 - Mesocarp: a sweet gelatinous substance that protects the seed, and attracts animals.

- Endocarpo: envolve cada semente, atrasando a germinação, mas sem inviabilizá-la. Deve ser retirado pelo beneficiamento.
- Semente: é o óvulo maduro e já fecundado, a partir do qual a planta crescerá quando encontrar as condições apropriadas.

The seeds are composed of endosperm, spermoderm and embryo. The first is the largest tissue in the seed, and its function is to nourish the embryo ("coffee seed") during germination, and is the part that will be roasted and ground for human consumption.

The second is the silvery film that surrounds the endosperm. Finally, the embryo, which is composed of the embryonic axis and two cotyledons, which will originate the first pair of leaves on the coffee plant, and will determine the presence of two seeds in the same fruit.