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Published In: Species Plantarum 1: 172. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library
 
 

Project Name Data (Last Modified On 5/27/2020)
Acceptance : Accepted
Note : Tribe Coffeeae
Project Data     (Last Modified On 6/2/2022)
Notes:

Coffea includes about 124 species of Paleotropical shrubs and small trees, with three of these cultivated for coffee, an important world commmodity crop. This genus is characterized by its branches with elliptic, usually opposite and distichous leaves usually with crypt-type domatia, persistent stipules that are triangular and shortly fused around the stem, axillary congested inflorescences with the bracts usually fused in pairs to form calyculi, homostylous, fragrant, 4-8-merous flowers, a reduced or only shortly developed calyx limb, white  funnelform corollas with the lobes convolute in bud, exserted narrow anthers and stigmas, and ellipsoid, fleshy, red to blackened, drupaceous fruits with two pyrenes enclosed in leathery walls.The stem apices often are resinous. The flowers of the cultivated species generally bloom for a short period, and the fragrance and appearance of coffee plantations in flower are impressive. The comments here are intended to provide an overview of the genus, but mainly are focussed on these plants in the Neotropics. 

The identities of the species of Coffea have sometimes been complicated to discern, and taxonomic treatments of this group have varied rather widely. This is apparently due at least in part to extenstive natural hyrbidization among the species. The main economic species are Coffea arabica (Arabica coffee), Coffea canephora (Robusta Coffee; syn. C. robusta), and Coffea liberica W. Bull ex Hiern (Liberica Coffee; syn. C. dewevrei, C. excelsa). See the Flora Mesoamericana Coffea treatment (Lorence, 2012) for a key to the three commonly cultivated species. In the Neotropics the first two of these are widely grown commercially, usually as hybridized cultivars: the more valuable Arabica Coffee is grown at relatively cooler, often higher (or more northern) elevations, and Robusta Coffee grows well in warmer, generally lower-elevation areas. Bean coffee is a very important world commodity, and also a very important commerical product and cultural element across Latin America. This region produces some of the world's best and most prized coffee, but ironically, often only second-rate coffee is consumed in many of these countries because the countries are not economically well-off so the best coffee is exported for the foreign exchange it brings. Coffea arabica and Coffea canephora are widely cultivated in this region in home garden plots for local use; Coffea liberica is also cultivated but less frequently, and more often as a curiosity (but its fruits are harvested and used also). Coffea plants often persist in the Neotropics after cultivation, and produce fertile seeds that germinate; these species do not seem to establish a permanent population or naturalize and spread, however. At least one of these three Coffea species is usually among the first 30 or so specimens made by botany students and first-time visitors to the tropics.  

The fruits of Coffea are morphologically, drupes of the Rubiaceae type, with two pyrenes that are enclosed by thickened, leathery endocarp and each contain one seed that naturally disperses inside this endocarp. The structure of the fruits and the terminology used for the cultivated species is less formal, however. Commercially, the fruit is often called a "cherry" and seed itself is the product. In processing, the seed is removed from the pyrene hull (or parchment or cascarilla), and then the seed coat or "silver-skin".

Observation of cultivated plants of Coffea arabica (St. Louis, CMT) finds that the main stems have a decussate arrangement of leaves and lateral branches, while the lateral branches extend horizontally (plagiotropic) without branching further and have a distichous leaf arrangement due to twisting in the internodes. The leaves persist for various seasons, even when partially damaged, or the leaves of the main stems and the basalmost leaves of the lateral branches are sometimes deciduous after a couple seasons. The flower buds form a year or more before they open, and are held on the stems as small green buds. The flower buds form in the leaf axils on apparently persistent short-shoots, and in the subtending axils of these short-shoots. The older flower buds mature and open essentially simultaneously, over a period of 3-4 days, while younger buds remain unopened until the following season.The flowers have a very sweet, perfume odor, which is strong when only a few flowers are open but difficult to detect when the tree is in full flower. The fragrance seems to be nocturnal, but remains weakly during the day also. The flowers are in their staminate phase for the first day, with the anthers erect and bright white. The next day the stigma lobes become white, enlarge, and separate, and the anthers appear to be aging but not completely dried. On the following day, the corolla and stamens are wilted or brown and dry, while the stigmas enlarge and brighten further. 

The circumscription of Coffea has varied widely, as detailed and developed by Davis in various studies. The name has been applied historically to various Rubiaceae genera with white flowers and drupaceous fruits, which are now separated and classified in various tribes (e.g., Zappi, 2000). The circumscription of Coffea was generally narrowed and clarified in the late 19th century, and at that time several species from Africa and Asia with similar characteristics except with a short and included style were separated in Psilanthus. Davis et al. (2011) then found using both molecular and morphological analysis that Psilanthus is nested within Coffea, and synonymized it, with the names transferred there and by Davis (2011). Several iother genera were separated from Coffea in Madagascar also, in particular Paracoffea, but those were also synonymized by Davis and collaborators (e.g., 2008). The phylogeny of Coffea was studied with molecular data by Davis and collaborators (e.g., Maurin et al., 2007; Davis et al., 2011), who found several lineages that were significantly correlated with biogeographic region. Davis et al. (2019, and references cited there) reviewed the distribution and conservation status of species of Coffea in their native ranges. 

Author: C.M. Taylor.
The content of this web page was last revised on 2 June 2022.
Taylor web page: http://www.mobot.org/MOBOT/Research/curators/taylor.shtml

Distribution:

Humid to wet forest vegetation, widely in the Paleotropics from Africa and Madagascar to southern and southeastern Asia, Papua New Guinea, and Australia; ca. 124 species in its native range, 61 of these in Madagascar, and 3 African species and an extensive number of hybrids of those and the African Coffea stenophylla cultivated world-wide in the humid tropics.

References:

 

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Shrubs and small trees, unarmed, terrestrial, without raphides in the tissues, sometimes resinous on stem apices. Leaves opposite or occasionally verticillate, petiolate, entire, with higher-order venation not lineolate, usually with foveolate domatia; stipules interpetiolar and shortly fused around the stem, triangular, often acute and aristate, apparently valvate in bud, persistent. Inflorescences axillary, subcapitate to shortly cymose or reduced, 1--several-flowered, subsessile or pedunculate, bracteate, with bracts often cupular and fused in pairs to form a calyculus. Flowers subsessile to pedicellate, bisexual, homostylous, protandrous, fragrant, diurnal; hypanthium turbinate to ellipsoid; calyx limb reduced or shortly truncate to 5-lobed, without calycophylls; corolla funnelform to salverform, white to pale pink, internally glabrous or villous in upper part of tube and on bases of lobes, lobes 5--8, elliptic to ligulate, convolute in bud, without appendages; stamens 5--8, inserted near top of corolla tube, anthers narrowly ellipsoid and prolonged, dorsifixed near base, opening by linear slits, without? apical appendage, exserted; ovary 2-locular, with ovules 1 in each locule, subpeltate on axile septum; stigmas 2, exserted. Fruits drupaceous, ellipsoid, fleshy, red to purple or black, with calyx limb persistent; pyrenes 2, hemispherical, chartaceous to coriaceous, abaxially smooth, adaxially with medial furrow; seeds 1 per pyrene, with testa thin and shiny.

 

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