288 cook: tribroma, a new genus of trees 



Tribroma Cook, gen. nov. 



Slender, erect trees, with strong upright shoots, each ending in a 

 whorled cluster of 3 lateral branches; leaves of upright shoots with long 

 petioles and broadly ovate-cordate blades, palmately veined, naked 

 above, clothed underneath with a very fine dense appressed stellate 

 pubescence, like the surfaces of the branches and petioles; leaves of 

 lateral branches broadly ovate-oblong, subsessile, the petioles very 

 short, representing only the confluent pulvini; inflorescences with 

 pseudodichotomous branching, with bracts at the articulations, form- 

 ing a broad, loose panicle or dichasium, produced near the ends of the 

 lateral branches, above the axillary buds of the young leaves, entirely 

 confined to the new growth; flowers small, inconspicuous, dark-colored, 

 dull reddish purple, the petals minute and the sepals only partly opened; 

 sepals broadly triangular, inflexed; petals much shorter than the sepals, 

 the basal hood with a single median rib, the limb rudimentary, repre- 

 sented by a minute oval, reflexed, nearly sessile appendage; staminodes 

 robust, clavate, clothed above with short pubescence, naked below; 

 ovary 5-angled, finely pubescent like the pedicels, sepals, petals and 

 staminodes, but none of the pubescence glandular; fruits ellipsoid, with 

 a very hard woody shell, the surface broken by deep irregular lacunae. 



Type, Tribroma bicolor {Theobroma bicolor Humb. & Bonpl., PI. 

 Equinox. 1: 94, ph. 30a, 30h.). 

 • 



The generic name Tribroma alludes to the fact that the lateral 

 branches are always produced in whorls of three. In Bernouilli's mono- 

 graph of Theobroma the name Rhytidocarpus was used for the section 

 that included T. bicolor; but to advance this name to generic rank 

 seems inadvisable, in view of the previous applications of closely simi- 

 lar names, such as Rhytidocarpaea and Rhji^icarpus, in other groups 

 of plants. 



The patashte tree is probably of South American origin, though the 

 original habitat has not been determined. In Central America it is 

 widely but rather sparingly cultivated by the Indians. The seeds are 

 used for the same purpose as those of the cacao tree, though generally 

 considered inferior in quality. The comparison of cacao and patashte 

 was made at a locality called Cacao or Secacao, on the Trece Aguas 

 Estate of Don Ricardo Fickert-Forst, in the Senahii District of the 

 Department of Alta Verapaz, eastern Guatemala. Specimens collected 

 at Cacao in May, 1914, are in the U. S. National Herbarium, the 

 sheets bearing numbers 862202-5. 



The contrasting characters of the genus Theobroma, as represented 

 by its type species, T. cacao, may be stated as follows: 



