Coffee

Morphology

  • The coffee plant is a woody perennial evergreen that belongs to the Rubiaceae family.
  • Two main species are cultivated today.
  • Coffea arabica known as Arabica coffee accounts for 75-80% of the world's production.
  • Coffea canephora, known as Robusta coffee, is more resilient plant than the Arabica shrubs, but produces an inferior tasting beverage.

  • The coffee plant can grow to heights of 10 meters if not pruned, but producing countries maintain coffee at three meters to ease picking.

Plant

  • Coffea Robusta is a shrub type plant and it 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 is a tree type plant and drives a straight up trunk with branches paired off outward and lower branches tend to droop downward.

Root

  • The root system can extend 20-25 km in total length and the absorbing surface of a tree ranges from 400 to 500 m2 .
  • There are main vertical roots, tap roots, and lateral roots which grow parallel to the ground.
  • To be thick and strong, the root system needs an extensive supply of nitrogen, calcium and magnesium.

Leaf

  • Oblong - ovate leaves of the coffee tree are shiny, dark green, and waxy.
  • The leaf area index is between 7 and 8 for a high-yielding coffee.
  • It is a bipolar leaf structure, where two leafs grow from the stem opposite each other.
  • The distance between leaf pairs and 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.

Flower

  • Three to four years after the coffee is planted, following a shower sweet smelling white flowers grow in dense clusters in the axils of the leaves.
  • Flowers have five-toothed calyx and a tubular five-parted corolla.
  • Five stamens and a single bifid style. Flowers last only a few days.
  • Sexually, the Coffea arabica is autogamous, in that it can pollinate itself, where as the Coffea Robusta can not pollinate itself.

Fruit

  • About 6-8 weeks after the flowers are fertilized, cell division occurs and the fruit remains as a pin head for a period that is dependent upon the climate.
  • The ovaries will then develop into drupes in a rapid growth period that takes about 15 weeks after flowering.
  • After pollination of the coffee plant, a small green coffee berry appears called a drupe.
  • This coffee berry grows to about 15-35 millimeters (0.5 inch to 1.25 inches) depending on species. The coffee berry grows in clusters.
  • When the coffee berry is ripe it turns red. At maturity, the coffee berry is bright red.
  • After what is considered ripe, the coffee berry turns brown to reddish brown and falls off the coffee tree.

Berry

  • There are typically two seeds per coffee 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 coffee berry also.

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Coffee

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