Common Trees of Puerto Rico and the Virgin Islands

MULBERRY FAMILY (MORACEAE)
19. Caucho, Central American rubber, castilla rubber Castilla elastica Cervantess
Caucho, including this and 2 related species
planted sparingly in Puerto Rico, is easily recognized
by: (1) the long, slightly drooping, stout,
hairy twigs wit11 2 rows of large hairy oblong
leaves 10-18 inches long and 4-8 inches broad, also
drooping; and (2) abundant milky juice in the
bark and twigs. The other species are separated
most1 by flon-er and fruit characters.
A &rge spreading evergreen tree becoming 70
feet or more in height and 1-3 feet in trunk diameter,
with buttresses forming at bnse of large
trunks. The light brown bark is smoothish, wit11
fine fissures, and thick, often having scars where
cut \\?it11 machetes by curious persons to see the
latex drip. Inner bark is ~vhitish and bitter with
latex also bitter. The unbrtincl~ed twigs are ween
\\.hen young but become brol~n, and have a 9 ong,
narrow, green, hairy terminal bud 2-234 inches
long, formed by n many-ridged scale (stipule) that
sheds, leaving n diagonal ring scar at each node.
The alternate leaves are spreacling from short
stout hairy petioles inch long. Leaf blacles are
oblong but broadest beyond the midclle, shortpointed
nt apes and heart-shaped at base, the edges
\\-it11 tufts of hairs simulating minute teeth, thin,
green and rough on upper surface, ancl light green
and soft hairy beneath.
Flon-ers are male and female on the same tree
(monoecious) but in separate flattened hencllike
clusters bordered by rows of overlapping scales
and borne along t.he twigs mostly back of the
leaves. Male clusters are commonly 4 together,
yh-1 inch across on stalks about 1 inch long, composed
of male flowers with numerous crowded
stamens less than 1/8 inch long and no calyx. Female
clusters are single, stalkless or nearly so,
forming a greenish-yellow disk 3/4 inch across, and
bordered by many broad, short-pointed, green,
finely hairy, overlapping scales. The crowded
female flowers are about l/q inch long, fleshy,
minutely hairy, greenish-yellow, tubular, angled
calyx surrounding and adhering to the white
ovary, \rhich has n yellow-green style and 2- or
3-forked protruding stigma.
The multiple fruit is a disk 11/2-2 inches in diameter
and x-1 inch thick, borclerecl by many
,men overlapping scales from the flower cluster
and composed of many cron-cled individual fruits
grown together. Each individual fruit is l/z+
incll lon and 1/4-% inch across, blunt-pointed and
half wit f in the disk, com osed of the fleshy, finely
hairy calyx, changing co f' or from yellow to green,
orange, and red, very juicy, almost tasteless but
sligl~tly sour, soon fermenting and molding, and
containing 1 white oblong seed %-1/2 inch long.
Seeds 800 to a ound. Flowering chiefly in spring,
and maturing P ruits in summer.
The mood is yellow brown, moderate1 soft,
lightweight, and not durable, Used in suerto
Rico chiefly for fuel.
With species distributed on the continent from
Biexico to Ecuador, Peru, Bolivia, and Brazil,
Oastilla was formerly an important source of rubber,
both from wild trees and plantations. Some
rubber is st,ill obtained from wild trees by cutting
or tapping the bark and collectin$ the latex, which
coagulates upon exposure. Cult~vation in Triniclad
ancl Tobago was not commercially successful.
Riost, rubber now comes from plantations of the
unrelated Par6 rubber tree (Devea) native in
Brazil. The Indians made mats for blankets and
clothing by beating out the bark.
Planted occasionally in Puerto Rico, sometimes
as n roadside tree for shade and ornament. Found
along the Arecibo-Utuado, Cides-Villalba, and
M:tr~cao-Mayagiiez highways. Also grown at St.
Thomas. It is a tree of openings in moist forests,
probably li ht-requiring, and grows rapidly.
RANGE.-L % ntive of Mexico and Central America
soubh to Colombia and Ecuador. In the West
Indies introduced into Cuba, Hispaniola, Puerto
Rico and St. Thomas, and Trinidad and Tobago.
Rarely planted in southern Florida.
OTHER COBIJLON NAJLES.-P~~O de goma, goma,
cnucliern (Puerto Rico) ; caucho (S anish) ; tirajala
(Dominican Republic) ; lrfol del hule
(Mexico) ; hule, ule (Guatemala, Honduras) ; uleule,
hule, rnnstate blanco (Panama ; caucho negro
(Colombia) ; castilla rubber, cast4 i oa rubber, Centrnl
American rubber (English) ; rubber, ule
(British Honduras).
BOTBNI~AL s~~o~~ars.-casfi22a kcti@&% 0. F.
Cook, 0. pnnnmensis 0. F. Cook.
The generic name, sometimes spelled Cmtilloa,
honors Juan del Castillo (1744-93), Spanish
nrlnacist and economic explorer, who came to
Lexico in 1787.
Rh