466 ANNUM, REPORT SMITHSONIAN INSTITUTION, 1911. 



Atlantic slopes and to the high mountains. Thus, in the mountain- 

 ous parts of eastern Guatemala (Alta Verapaz), where according to 

 the native saying "it rains 13 months out of every 12," tree ferns 

 are exceedingly abundant, a few species occurring at and near sea 

 level, but the most of them at from 4,000 to 6,000 feet altitude. 

 West of this region, in the dry interior basin, they are wanting; and 

 only two species, Cibotium Wendlandi and Hemitelia costaricensis, 

 are reported from the higher region near the Pacific, even the moist 

 forest belts of the volcanoes Fuego and Agua having none, so far as 

 known. 



In Costa Rica a relatively small number of tree ferns are found in 

 the moist Atlantic lowlands, but they are elsewhere of very general 

 occurrence, excepting only the half desertlike slopes facing the Pacific 

 and the dry and open portions of the interior table land, which has 

 a temperate and delightfully equable climate. The latter area 

 (meseta central) is relatively small, and one has only to go out a few 

 miles to the lower mountain slopes to find tree ferns in profusion. 

 The greater part of Costa Rica, however, and by far the most inter- 

 esting, is the exceedingly broken, mountainous region to the north- 

 ward, from which rise the four great volcanic peaks Turrialba (11,128 

 feet), Irazu (11,312 feet), Barba (9,412 feet), and Poas (8,786 feet), 

 from east to west. These intercept most of the moisture from the 

 Gulf, and it is here that the Cyatheaceae reach their highest develop- 

 ment, both as to species and size and number of individuals, in any 

 part of North America. Christ, indeed, regards it as "the richest 

 tree fern region of the world." Certainly it is an endemic center of a 

 high order, and when adequately explored is likely to yield many 

 more than the 50 species it is now known to contain. It embraces 

 altitudes above 5,000 feet; and although snows are wanting from all 

 Costa Rican volcanoes, heavy frosts occur more or less regularly from 

 6,000 feet upward. The extremes of temperature endured by the 

 tree ferns of this region must be very great. 



Chiriqui, the westernmost Province of Panama, apparently does 

 not differ greatly from Costa Rica as a tree fern region. Although 

 there are a few coastal species, here also the great majority are found 

 in the high mountains, which form a definite cordillera paralleling 

 the coast line, east and west. Recent exploration has shown that 

 they are mainly those known hitherto only from Costa Rica. The 

 Cordillera gradually decreases eastward, until in the Canal Zone only- 

 three or four lowland tree ferns are found. One of these, Hemitelia 

 petiolata, first described from Panama, is common in ravines and wet 

 thickets. 



In Mexico, also, as might be expected, tree ferns are wanting from 

 the interior, arid, high plateau region, whose flora has been so thor-. 

 oughly investigated during the past 35 years. Upward of 20 species 



