Second Contribution to the Coastal and Plain Flora of 



Yucatan. 



CHARLES F. MILLSPAUGH, M.D. 



That portion of Yucatan considered in these contributions is 

 peculiar in its biologic characters, differing essentially from the sur- 

 rounding region, especially in its flora. Here all plants have a desic- 

 cated appearance due to their struggle against drought, while in the 

 neighboring areas the wealth of exuberant vegetation is marked. The 

 cause is readily understood when we note the great difference that exists 

 between the orographic characters of the peninsula and those of the 

 neighboring countries — Honduras, Guatemala, Chiapas and Tabasco. 

 In Chiapas there are numerous mountain chains of considerable alti- 

 tude formed of igneous and sedimentary rocks; in Yucatan this char- 

 acter is entirely absent; the great undulous plains being of calcareous 

 formation, simply and slightly inclined toward the north, their sur- 

 faces studded with a vast multitude of mere hillocks and depres- 

 sions. In Tabasco, Guatemala and Honduras true mountains exist. 

 Passing from Belize, after having crossed the boundary Rio Hondo, 

 one climbs two broad but not very high ridges, reaching the first 

 plateau of the central table-land whereon is situated the village of 

 Teaich^ at i6o meters above the sea level. The second plateau about 

 Ixconconal has an altitude of 250 meters, the highest plain in the 

 region. Descending to the neighborhood of Halatun (i2o met ) one 

 reaches the low lands about Iturbide (i 10 met.) and Yaxha (100 met.), 

 and after passing down to other ridges of less altitude but consider- 

 able breadth one reaches the city of Tikul (25 met.) and the low lands 

 that extend over the whole northern and eastern portion of the penin- 

 sula, the region embraced in these contributions. 



This peculiar orographic difference between the peninsula and 

 its neighboring states is more than equaled by the hydrographic con- 

 ditions. While all the bordering country is well watered by large living 

 streams, many of them navigable for long distances inland, the plains 

 of Yucatan have no surface water whatever, the porosity of the coral- 



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