Notes on the North American species of Phanerophlebia* 
WILLIAM R. Maxon 
In determining recently two species of Phanerophlebia collected 
by the writer in the mountains of Chiriqui, in western Panama, it 
became necessary to go somewhat critically over most of the ma- 
terial of this genus in the U.S. National Herbarium. Specimens 
have been received from various sources during the past twelve 
years, so that it is now possible to separate the species somewhat 
more exactly than at the time of Dr. Underwood’s revision of the 
genus,} and partly by the use of characters not previously em- 
phasized. The following key and notes are offered merely as 
supplementing that treatment. One species, P. guatemalensis, 
appears not to have been well founded. 
Key to the North American species of Phanerophlebia 
Venation copiously areolate. 
Plants of lax spreading habit; pinnae few (5-11), normally 
3-5-5 cm. broad; veins distant (mostly 3-3.5 mm. apart), 
spreading at v wide angle; sori distinctly infra- 
medial upon i veinlets, the first row distant usually 
about 2 mm. from the midvein, the other sori similarly 
situated or often nearly basal upon the branches 1. P. juglandtfolia. 
Plants apparently of more upright habit; pinnae numerous 
(16-20), mostly 2-3 cm. broad; veins closer, usually 
or supramedial (rarely subterminal), the first row usually 3-5 
distant from the midvei 3. P. remotispora. 
Venation wholly free, or the veins ean anastomosing near the 
margin. 
Pinnae 3-5, cordat t least sul 1 t the b 2. P. pumila, 
Pinnae 10-30, variously cuneate, or unequally rounded or 
auriculate at the base, never cordate. 
Sori borne in a definite much nearer the margin than 
the midvein. 5. P. umbonata. 
Sorioccupying a medial zone or generally distributed 
over the — 
* Published by permission of the yaaa of the Smithsonian Institution. 
ft Bull. Torrey Club 26: 205-216. 15 My 
23 
