Tropie Zone: Costa Rican Region. 671 
stellato-tomentosum, Ardisia irasuensis, A. laevis, Eupatorium ixiocladon, Oreopanax Oerstedianum, 
and at the upper limit of oaks Arctostaphylos rubescens and Buddleia alpina. — This oak forest 
on Volcan Irazu is very different from that either of Poäs, or Turrialba in Costa Rica. The 
remnant of this forest is a narrow belt of stunted oaks just below the ash-cone and it gives way 
to a rather scattered growth of small trees and bushes which become more sparse and small as 
the summit is approached. — The oaks on the mountains in Panama at 4,200—8,000 feet, 
discovered by Dr. SEEMANN, consist of Quercus glabrescens, Q. aristata, Q. bumelioides together 
with Alnus Mirbelii, an alder which extends north to Guatemala. Chamaedorea pacaya occurs 
in barrancas at 7,000 feet. 
Mountain Summit Formations. (Including the “paramos”.) At 10,000 feet 
the oaks are stunted and covered with Usnea. They occur on Volcan de 
Barba mixed with Gaultheria Oerstediana, Gunnera insigmis (the most northern 
representative of the genus) and a Calceolaria. The sides of the crater are 
clothed with thick bushes of Psidium costaricense, Myrtus Oerstedii, Myrsine 
rapanea and several others. — There is no trace of vegetation on the upper 
part of Volcan de Reventado. The crater lake, however, is surrounded by 
compact rows of oaks supporting various epiphytic plants such as Odonto- 
glossum Oerstedi. Here also grow Senecio Oerstedianus, Hieracium irasuense, 
as well, as species of Vaccinium, Viola and Geranium. — On: the higher parts 
of Volcan Irazu, all arboreous vegetation ceases. The trachyte covered with 
vegetable mould is thickly carpeted with Zupinus and Alchemilla. At 11,000 feet 
in volcanic sand are found tufts of Chronolaena lavandulifolia, Castilleja ira- 
Suensts, Pernettya coriacea, Vaccinium densiflorum, Sphacele alpına and two 
other species, which form thick bushes six to seven feet high clothed with 
Usnea and a leafless, yellow Viscum. 
According to HEMSLEY, the mountains in western Veraguas, Panama possess a vegetation 
resembling the Mexican highlands. Species of Alnus and Rubus are found with Fuchsia and 
Salvia; the brake Pteris aquilinum grows with Lupinus and Ageratum. Oaks and palms are inter- 
mingled, while the following genera are represented: Ageratum, Centradenia, Clematis, Conostegia, 
Freziera, Fuchsia, Galium, Euphorbia, Smilax, Styrax, Salvia, Rondeletia, Rhopala, Equisetum and 
opezia 
Savanna Formation. Savannas are found especially on the Pacific coast 
of Costa Rica. The savannas situated between the coastal and main cordilleras 
are interspersed with woodland and may be compared to an archipelago of 
savanna islands in a forest-sea. This character of the landscape extends to the 
border of Panama, and as far, as the southern end of the Chiriqui cordilleras. 
The savannas in Panama ‘) exist only on the Pacific side of the Isthmus, 
where they form a grassy belt sixteen to eighteen miles broad lying between 
the littoral formation and the mountains. — In Costa Rica the plants of the 
Savannas are, according to TONDUZ: Curatella americana, Byrsonima crassı- 
Jolia, Miconia argentea, and the grasses in the list from the “Savanes de la 
Cruz” are species of Sporobolus, Andropogon, Trachypogon, Paspalum, Seleria, 
Cyperus and Rhynchospora°). 
ln 
1) Cowerı, ne Explorations in Panama, see Bibliogr. p. 82. 
2) Tonuz, An.: Herborisations au Costa Rica; see Bibliogr. p. 86. 
