MULBERRY FAMILY (MORACEAE) 



19. Caucho, Central American rubber, castilla rubber 



Castilla elastica Cervantes* 



Caucho, including this and 2 related species 

 planted sparingly in Puerto Rico, is easily recog- 

 nized by: (1) the long, slightly drooping, stout, 

 hairy twigs with 2 rows of large hairy oblong 

 leaves 10-18 incjies long and 4— S inches broad, also 

 drooping; and (2) abundant milky juice in the 

 bark and twigs. The other species are separated 

 mostly by flower and fruit characters. 



A large spreading evergreen tree becoming 70 

 feet or more in height and 1-3 feet in trunk diam- 

 eter, with buttresses forming at base of large 

 trunks. Tiie ligiit brown bark is smoothish, with 

 fine fissures, and thick, often having scars where 

 cut with machetes by curious persons to see the 

 latex drip. Inner bark is whitish and bitter with 

 latex also bitter. The unbranched twigs are green 

 when young but become brown, and have a long, 

 narrow, green, hairy terminal bud 2-21^ inches 

 long, formed by a many-ridged scale (stipule) that 

 sheds, leaving a diagonal ring scar at each node. 



The alternate leaves are spreading from short 

 stout hairy petioles 1,4 inch long. Leaf blades are 

 oblong but broadest beyond the middle, short- 

 pointed at apex and heart-shaped at base, the edges 

 with tufts of hairs simulating minute teeth, thin, 

 green and rough on upper surface, and light green 

 and soft hairy beneath. 



Flowers are male and female on the same tree 

 (monoecious) but in separate flattened headlike 

 clusters bordered by rows of overlapping scales 

 and borne along the twigs mostly back of the 

 leaves. Male clusters are commonly 4 together, 

 3.4-I inch across on stalks al)out 1 inch long, com- 

 posed of male flowers with numerous crowded 

 stamens less than % inch long and no calyx. Fe- 

 male clusters are single, stalkless or nearly so, 

 forming a greenish-yellow disk % inch across, and 

 bordered by many broad, short-pointed, green, 

 finely hairy, overlapping scales. The crowded 

 female flowers are about 1/4 inch long, with fleshy, 

 minutely hairy, greenish-yellow, tubular, angled 

 calyx surroiniding and adhering to the white 

 ovary, which has a yellow-green style and 2- or 

 3-forked protruding stigma. 



The multiple fruit is a disk IV2-2 inclies in di- 

 ameter and %-l inch thick, bordered by many 

 green overlapping scales from the flower cluster 

 and composed of many crowded individual fruits 



grown together. Each individual fruit is 14-% 

 inch long and i/4-% inch across, blunt-pointed and 

 half within tlie disk, composed of the fleshy, finely 

 hairy calyx, changing color from yellow to green, 

 orange, and red, very juicy, almost tasteless but 

 slightly sour, soon fermenting and molding, and 

 containing 1 white oblong seed %-i/4 inch long. 

 Seeds 800 to a pound. Flowering chiefly in spring, 

 and maturing fruits in summer. 



The wood is yellow brown, moderately soft, 

 lightweight, and not durable. Used in Puerto 

 Rico chiefly for fuel. 



With species distributed on the continent from 

 Mexico to Ecuador, Peru, Bolivia, and Brazil, 

 CattfUJa. was formerly an important source of rub- 

 ber, both from wild trees and plantations. Some 

 rubber is still obtained from wild trees by cutting 

 or tapping the bark and collecting the latex, which 

 coagulates upon exposure. Cultivation in Trini- 

 dad and Toliago was not commercially successful. 

 Most rublier now comes from plantations of the 

 unrelated Para rubber tree {flevea) native in 

 Brazil. The Indians made mats for blankets and 

 clothing by beating out the bark. 



Planted occasionally in Puerto Rico, sometimes 

 as a roadside tree for shade and ornament. Found 

 along the Arecibo-Utuado, Ciales-Villalba, and 

 Maricao-Mayagiiez highways. Also grown at St. 

 Thomas. It is a tree of openings in moist forests, 

 probably light-requiring, and grows rapidly. 



R.AXGE. — S'ative of Mexico and Central America 

 south to Colombia and Ecuador. In the AVest 

 Indies introducetl into Cuba, Hispaniola, Puerto 

 Rico and St. Thomas, and Trinidad and Tobago. 

 Rarely planted in southern Florida. 



Other co]\rMON names. — palo de goma, goma, 

 cauchera (Puerto Rico) ; caucho (Spanish) ; tira- 

 jala (Dominican Republic) ; arbol del hule 

 (Mexico) ; hule, ule (Guatemala, Honduras) ; ule- 

 ule, hule, mastate bianco (Panama) ; caucho negro 

 (Colombia) ; castilla rubber, castilloa rubber, Cen- 

 tral American rubber (English) ; rubber, ule 

 (British Honduras). 



Botanical synonyms. — Cast'dJa lactifua O. F. 

 Cook, C . pann?nen-ii.i O. F. Cook. 



The generic name, sometimes spelled Oa.sfilloa. 

 honors Juan del Castillo (1744-93), Spanish 

 pharmaci.st and economic explorer, who came to 

 Mexico in 1787. 



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