MAXON—STUDIES OF TROPICAL AMERICAN FERNS. 155 
1. Dicksonia lobulata Christ, Bull. Herb. Boiss. II. 6: 187. 1906. 
TYPE LOCALITY: Cerros de Velirla, Copey, Costa Rica, altitude 2,600 to 2,700 meters. 
DistRIBUTION: Known only from Costa Rica. 
Three sheets of the type number ( Tonduz 11789) are in the U. 8. National Herbarium, 
and the species is probably known only from this collection. The venation is that 
ascribed by Karsten to Dicksonia gigantea, but the plant differs materially from that 
species in its broader and more obtuse segments, as well as in its larger sori. . 
2. Dicksonia gigantea Karst. Fl. Columb. 2: 177. 1869. 
Dicksonia navarrensis Christ, Bull. Herb. Boiss. II. 6: 188. 1906. 
Type LocaLiry: Mount Guadelupe, Andes of Bogota, Colombia, altitude 2,600 
meters. 
DistrRisuTION: High mountains of Colombia, Panama, and Costa Rica. 
IntustrATION: Karst. loc. cit. pl. 193; Ann. Rep. Smiths. Inst, 1911: pil. 13. f. B, 
pl. 14 (as D. navarrensis). 
A comparison of authentic material of Dicksonia navarrensis, both of Wercklé’s 
original collection and a more ample series collected near the type locality by the 
writer in 1906, with Karsten’s description and illustration of D. gigantea leaves scarcely 
any doubt that they represent a single species. More recently gathered material from 
Chiriqui, Panama, strengthens this conclusion. Not all fertile segments have simple 
veins, however, as supposed by Karsten. This is particularly true of the larger, 
fully fertile segments of the lower and middle parts of the pinnule, in which the fertile 
veins of the proximal side of the segment are frequently once forked, while those of 
the distal side are almost invariably simple. The branches of the veins are delicate, 
however, and inconspicuous, their development being accompanied by only a slight 
crenation of the fertile lobes. 
Dicksonia gigantea is much more closely related to D. lobulata than to D. karsteniana, 
as indicated in the key. 
The following specimens are in the U. S. National Herbarium: 
Costa Rica: Without definite locality, Wercklé (4 sheets, ex herb. Christ). With- 
out locality, J. J. Cooper (3 sheets). Mountains 5 miles south of Cartago, 
alt. 1,800 meters, Mazon 513; Mazon 528. 
Panama: Humid forest between Alto de los Palmas and Cerro de la Horqueta, 
Chiriqui, alt. 2,100 to 2,268 meters, March 18, 1911, Mazon 5518. 
8. Dicksonia karsteniana (Klotzsch) Karst. Fl. Columb. 2: 179. 1869. 
Balantium karstenianum Klotzsch, Linnaea 20: 444. 1847. 
TYPE LocaLity: Colombia. 
DistrisuTion: Wet forests of the high mountains of Venezuela, Colombia, and 
Costa Rica. 
IntustTRaATIon: Karst. loc. cit. pls. 194, 195. f. 7-17. 
Known to the writer chiefly from Costa Rica specimens collected in the vicinity 
of Coliblanco, upon the slopes of the Volcano Turrialba, altitude about 1,950 meters 
( Maxon 325), which agree fairly well with Karsten’s illustration and with fragmentary 
South American and Costa Rican material in the Underwood Fern Herbarium at the 
New York Botanical Garden. Its relationship is apparently with Dicksonia ghies- 
breghtit, from which it differs in the characters noted under that species. 
4. Dicksonia ghiesbreghtii Maxon, sp. nov. 
Caudex 4 to 5 meters high; fronds essentially tripinnate; primary rachis not seen; 
primary pinne linear-oblong, acuminate, not strongly asymmetrical, 60 to 70 cm. 
long, about 20 cm. broad, the secondary rachis 2 mm. thick, dull light brownish, 
slightly rough from the partial abrasion of the articulate turgid dirty yellow capillary 
scales; pinnules numerous, contiguous, alternate, sessile, inserted 2 to 2.5 cm. apart 
upon each side of the rachis, linear-oblong, long-acuminate, 8 to 12 cm. long, 2 to 2.5 
