38 CONTRIBUTIOlSrS FROM THE NATIONAL HERBARIUM. 



West Indies and Central America, southward into South America ; type from 

 Caracas, Venezuela. 



Leaf axis stout, light greenish brown; primary branches 2 or several pairs, 

 these once or twice dichotomous (rarely developing a secondary axis), the 

 internodes at least partially naked; segments mostly linear, dilatate (the 

 sinuses obtuse), entire, revolute. 



5. Dicranopteris underwoodiana Maxon, N. Amer. Fl. 16: 59. 1909. 

 Temperate region of Chiapas, the type locality. Also in the high mountains 



of Quiche, Guatemala. 



Leaf axis reddish brown, 2 to 3 mm. in diameter ; primary branches usually 

 2 pairs, twice dichotomous (not developing a secondary axis), the primary 

 internode nearly naked, the secondary ones fully pectinate; pinnae linear, 18 

 to 30 cm. long, the rachises closely invested with short rusty scales. 



6. Dicranopteris palmata (SchafEn.) Underw. Bull-. Torrey Club 34: 259. 1907. 

 Mertensia palmata Schaffn. ; Fee, Mem. Foug. 9: 40 (32). 1857, name only. 

 Gleichenia palmata Moore, Ind. Fil. 380. 1862, name only. 



Mountains of Veracruz, the type from Orizaba. Also in Guatemala (Alta 

 Verapaz), eastern Cuba, and the Blue Mountains of Jamaica, at altitudes of 

 900 to 1,650 meters. 



Leaf axis olivaceous, opaque; primary branches 2 or 3 pairs, divergent, 

 usually 2 to 4 times dichotomous (rarely developing a secondary axis), the 

 first and second internodes usually naked ; pinnae 20 to 25 cm. long. 



2. CYATHEACEAE. Tree-fern Family. 

 (Contributed by Mr. William R. Maxon.) 



Eeferences : Cyatheaceae, Diels in Engl. & Prautl. Pflanzenfam. 1 * : 113- 

 139. 1899; Maxon, The tree ferns of North America, Ann. Rep. Smiths. Inst. 

 1911: 463-491. pi. 1-15. 1912. 



Mainly treelike plants of moist tropical regions, the rhieome stout and 

 woody, decumbent, oblique, or usually erect, and 1 to 15 meters high or more, 

 naked, with smoothish, usually tesselate leaf scars, or rough and partially 

 sheathed by the imperfectly deciduous stipe bases of the fronds of previous 

 years; fronds borne in a terminal scaly crown, several or many, ascending to 

 recurved, the blades 1 to 4-pinnate, up to 4 meters long, usually broad ; sori 

 indusiate or nonindusiate, nearly globose, borne dorsally upon the veins on the 

 under surface of the blade or at the margin, the receptacle elongate, of various 

 form and vestiture; sporangia numerous, crowed radially in several ranks, 

 opening horizontally, the annulus oblique, with or without a stomium of thin- 

 walled cells; spores triplanate. 



The Cyatheaceae, or tree-fern family — the latter name given because, in 

 contradistinction to all other families of ferns, the species are nearly all 

 arborescent in habit of growth — are practically confinefl to tropical and siib- 

 tropical regions and attain their best development, both as to luxuriant growth 

 and as to number of species and individuals, in mountainous regions which 

 have a nearly uniform, moist climate. Except in a very few cases they ap- 

 parently can not endure extremes of either drought or cold. Thus in Mexico. 

 as in Central America, they are practically confined to the Atlantic slopes and 

 to the higher mountain regions that are constantly swept by the moistun^ 

 laden trade winds from the Gulf of Mexico. This territory embraces Vera- 

 cruz and Tabasco and most of Oaxaca and Chiap:is. From the arid interior 

 plateau regions they are altogether lacking. Comparatively little material hav- 

 ing been collected in extreme southeastern Mexico in recent years, our knowl- 



