Biology of a coffee plant

How do we call the various parts of a coffee plant?
Rows of Coffee Plants
04
Sep

The biology of a coffee plant

Seed growing up

Figure 1 -Biology of a coffee bean: names of various parts from a seedling (Wintgens, 2009).

The biology of coffee plants is not different from other plants. Nonetheless, here the various parts in the life of a coffee plant will be named, starting off with the seed. A coffee seed develops a radicle (If it is not used to make coffee at least). This radicle if growing out into the hypocotyl, which compromises the stem and roots. Meanwhile the stem is growing the cotyledon (A leaf like structure) start unfolding. When the cotyledon is large enough it will shed the seed-shells and the stem will continue growing. The bit of stem following the cotyledon is name epicotyl. From here, the first two leaves will start growing. Lastly, at the very top of the plant a new leaf-like structure will occur which is called the plumule (See figure 1) (Wintgens, 2009).

Coffee plants are either named bushes or trees. The coffee-pragmatist looked into the truth and found out that both are true. How is this possible? It has to do with the place the plant is growing. Naturally, coffee plants grow in the understory (Below other trees). Here there is only enough light for the coffee plant to small heights at which you would call a plant a bush. However, in the right conditions with enough light the trees will grow higher and can be classified as trees (Coffee-Pragmatist, 2019).

A plantation of coffee trees

Figure 2 – A plantation of coffee trees or bushes in the mountains (Coffee-Pragmatist, 2019).

 

Botanical drawing coffee plant showing the leaves, flowers and berries

Figure 3 – A botanical drawing of a coffee plant that dates from around 1880.

The leaves of a coffee plant are relatively large and at a tree typically a mixture of dark green (older) leaves and new light green leaves can be found (See figure 3). When in flower, a whole branch will be filled with small white flowers which afterwards turn into green unripe berries. Those berries will ripen to a bright orange color later on when they are ready to harvest. Within the berry a small seed that is light brown of color, not at all like the coffee bean most people know. It will only get the black color and cracked structure after roasting in.

The seeds of a coffee plant, normally referred to as coffee beans, are the most used part of the plant although other parts are edible/usable as well.  We do not use the entire coffee bean, only the inner parts of the coffee bean are used to make coffee. A coffee bean consist of 7 parts (See figure 4). The first layer is the outer skin, also called pericarp or exocarp. This layer is very thin and underneath lays the mesocarp and the pectin layer. All of this will be peeled of before using a coffee bean for coffee. Then there is the endocarp, epidermis, endosperm and the clear cut. Those layers together make up of how we usually encounter a (roasted) coffee bean (Wikipedia, 2019).

Figure 4 – 1: Center cut; 2:endosperm; 3:Epidermis; 4: Endocarp; 5: Pectin layer; 6: Mesocarp; 7:Exocarp (Wikipedia, 2019).

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