2 BULLETIN 30, PORTO RICO EXPERIMENT STATION. 
Mocha, and Murta ; to the Liberian group belong Liberica, Excelsa, 
Dewevrei, Abeokutse, and Dybowskii: and to the robustoid group 
belong Robusta, Canephora, Laurentii, Quillou, Coffea Uganda 
hybrid, and C. congensis hybrids. 
ARABIAN GROUP. 
The Arabian is the largest' of the three groups and includes the 
greater part of the coffees of South and Central America, the 
West Indies, that known as Java, 2 and in short what the public 
generally knows as " coffee " where no qualifying adjective is ap- 
plied. In this group are found the best cup coffees. 
The leaves of the Arabian group are smaller and thinner than 
those of the Liberian group, and the trees 3 are smaller than those 
of either the Liberian or the robustoid group. The pulp is much 
thinner than that of many members of the Liberian group, and 
the ripe fruit drops more readily, necessitating picking at shorter 
intervals. 
Porto Rican Coffee. 
According to historians, coffee of Arabian stock was introduced 
from the Far East into Java and other places, whence it spread to 
Martinique toward the close of the first quarter of the eighteenth 
century. Within the next quarter of the century it found its way 
to the other islands of the West Indies, and was taken by emigrants 
from Haiti to Porto Rico, where it is said to have produced a crop 
of some 700,000 pounds in 1770.* A century later the annual ex- 
portation from Porto Rico ranged from 15,000,000 to 25,000,000 
pounds, and by 1896 had reached the maximum, 57,961,291 pounds. 
with the second highest exportation, 51,125,620 pounds, in 1915. 
According to the Federal census, 159,860 acres of coffee were 
harvested on the island in 1919. 5 
Porto Rican coffee is botanicaily known as Coffea ardbica. The 
shrub is a small evergreen which attains a height of 10 to 15 feet. 
When young it has a single, very erect trunk or stem which later 
bends under the weight of its crop. Other stems of similar form 
and habit then develop along it, giving to the whole a somewhat 
bushy appearance. The lateral branches are opposite in arrange- 
ment, horizontal, and in pairs. Occasionally they occur in whorls 
of three. The leaves, which are dark, glossy green on the upper 
surface and light green underneath, opposite, and in pairs, are 
generally 1| to ^2 inches broad by 4 to 7 inches long, the length 
being 2-| to 3 times the breadth. They are elliptical in form, with 
acuminate tip and attenuate base. (PI. I, fig. 1.) 
The flowers are pure white with five or six petals, and are borne 
on short pedicels in one to four axillary clusters of one to four 
flowers each. The blossoming season is irregular, and flowering 
may take place at any time from December to May. At Mayaguez 
the principal blossoming occurs usually in February and March, 
and sometimes in January and April, the season being earlier on 
3 At present the Arabian coffee forms a very small percentage of the Javan crop. 
3 The term " tree" is arbitrarily used in this bulletin to cover all forms of Coffea spp. 
* Informe de la cafe. National Coffee Growers' Association, Ponce, P. R., 1910, p. 128. 
8 Ann. Rpt. Governor of Porto Rico. 1920, p. 319. 
