564 
1. P. aquilina L. Rootstock wide-creeping: stipes scattered, 3 to 7 dm. high, 
stramineous: fronds ternate, triangular-ovate, 3 to 6 dm. each way, smoothish or in 
one form woolly pubescent beneath; lower pinnules pinnatifid.—Var. CAUDATA Hook. 
Pinnules often linear and entire or with the segments less crowded.—In woods, 
Houston (Hall), 
6. PELLAA Link. 
Sori intramarginal, terminal on the veius, at first dot-like, at length 
confluent forming a marginal line: indusitm membranous, formed of 
the altered and reflexed margin of the segment.—Rock ferns of small 
or medium size. 
§ 1. Terture coriaceous: indusium broad, conspicuous. —ALLOSORUS Baker. 
* Pinnules or segments obtuse or acute. 
+ Fronds pinnate or bipinnate. 
1. P. atropurpurea (L.) Link. Rootstock short, with narrow ferruginous scales: 
stipes 6 to LO cm. long, dark purplish brown, smooth: fronds 5 to 20 em. long, 2 to 9 
con. wide, simply pinnate or bipinnate below; pinnwes and upper pinne 1.5 to 4 em, 
long, 2 to 4 mm, wide, nearly sessile, smooth.—Crab apple, Gillespie County (Jermy). 
2. P. aspera (Hook.) Baker. Rootstock short, with ferruginous scales: stipes 
densely cespitose, 2 to 5 em. long, brown or black with narrow whitish seales and 
bristly hairs: fronds 6 to 15 cm. long, 2to 3 cm. wide, bipinnate, covered on both 
sides with whitish hairs; segments short, 2 to 4 min. long, the upper portions of the 
pinne merely pinnatifid.—San Antonio (Palmer), Chenate Mountains, Presidio 
County (Nealley), Uvalde Cation (Afrs. Young). 
+ + Fronds tri-quadripinnate at base. 
3. P. pulchella (Mart. & Gale.) Fee. Stipes densely tufted, with ferruginons 
scales at base, 7 to 18 em. long, brown: fronds 8 to 16 em, long, 3 to 10,cm. wide, 
gradually simpler above; segments 2 to 6mm. long, oval or cordate-ovate, smooth.— 
Uvalde Cation (Mrs. Young), Mountains near El] Paso (G. 2. Vasey). 
* * Pinnules mucronulate or decidedly acute. 
4, P, ternifolia (Cav.) Link. Rootstock short: stipes 5 to 15 cm. long, dark 
brown or black: pinne usually 9 to 15 pairs, all but the uppermost trifoliate; seg- 
ments mostly linear, sessile or the middle one slightly stalked; margins much 
inflexed.—Limpia Cation, Presidio County (Nealley). 
5. P. Wrightiana Hook. Rootstock short, thick, densely chaffy: stipes crowded 
purplish-brown, 1 to 1.5 dm, long: fronds 8 to 25 cm. long, 5 to 10 em, wide, pin, 
nate; pinne mostly lanceolate, with several pairs of pinnules, occasionally reduced 
to only three when it approaches the preceding; pinnules elliptical, short, mucron- 
ulate, the middle one short-stalked.—Granitic rocks, Llano County (Reverchon), 
Gillespie County (Jermy), both resembling P. ternifolia in the trifoliate pinne. 
§ 2. Terture coriaceous: the ultimate seqments broad and flat with very narrow indusia.— 
PLATYLOMA J. Sm. 
6. P. flexuosa (Kaulf.) Link. Rootstock rather slender, creeping: stipes 1.2 to 
3.5 din. long, grayish-red, passing into a flexuose rachis: fronds 1.5 to 7 dm. long, 
bi-tripinnate with the secondary rachises also zigzag and flexuous; pinnae mostly 
alternate; pinnules | to 1.5 em. long, roundish-ovate, smooth, soon becoming flat.— 
Southwestern Texas (Wright, Palmer), Llano County ( Reverchon), Youngblood County 
(Jermy), Limpia Cation, Presidio County (Nealley). The second form mentioned in 
Contr. U. 8. Nat. Herb. 1,61, belongs to the next species, 
