Manual de Plantas de Costa Rica 93 
discovery of new species will eventually tend to decrease. Nevertheless, the in- 
tensive exploration of Costa Rica over the last 15 years has uncovered an aver- 
age of 57 species per year (new to science or to the country), surely indicating that 
many species are yet to be discovered (see Table | and Fig. 1). 
Smaller-scale studies, such as at biological stations (e.g., for La Selva; see Grayum 
& Churchill, 1987; Hammel, 1990) or for regions such as the Osa Peninsula (R. Aguilar, 
pers. comm.), demonstrate somewhat similar results. Even at Barro Colorado Island in 
Panama (Foster & Hubbell, 1990) and Palo Verde National Park in Guanacaste (Chava- 
rria et al., 2001), small sites whose flora has been well studied, 25 and 10 new records 
(respectively) have been added over the past 12 years. All this indicates that the flora of 
tropical forests should be studied and monitored on a long-term basis and that present 
attempts to describe the different vegetation types of Costa Rica are still preliminary. 
Several authors (cf. Wercklé, 1909; Standley, 1937b; Gémez P., 1986) have previ- 
ously documented in detail the close phytogeographical relation that exists between the 
vegetation of Costa Rica and that of South America, especially the northwestern part of 
Colombia and the Pacific coast of Ecuador (see Origin of the flora, below). Wercklé 
(1909: 5), in fact, described the flora of Costa Rica as “‘an outpost of the northern equa- 
torial flora in the continent of the North.” This pattern of biotic affinity has also has 
been confirmed for other groups, such as bryophytes (Bartram, 1928), birds (Stiles & 
Skutch, 1989), and butterflies (DeVries, 1987). Given the relationships and wealth of 
the flora, many scientists have tried to describe the different types of vegetation within 
the country during the past 155 years (see Gémez P., 1986, and the chapter on History 
for a clear chronology). 
| ogically, as one continues to study any particular geographic area, the rate of 
Estado del conocimiento de la flora costarricense 
9000 
8000 8249 
7000 7388.07 
6000 6086. ——_ 
5000 5000. 
4000 [- |+--# spp|| 
3000 [ 
2000 fe 
1000 1218 f 
0 q q q q 
1850 1900 1950 2000 2050 
Ano 
Numero de 
espermatofitas 
Fig. 1. State of knowledge of the Costa Rican Flora. 
