8 



24. A. Serra, Langs & Pisch. 



25. A. bissectum, Sw. 



cccc. Fronds bi-tripinate, rarely simply pinnate. (See A. lunulatum, var. strictum). 

 d. Texture firm, cliartaceous, sori radiating, surface more or less striated. 



26. A. pnemorsum, Sw. 



27. A. cuneatum, Lam. 



dd. Fronds varying from simply pinnate to decompound. 



28. A. auritum, Sw. 



29. A. fragrans, Sw. 



30. A. scandicinum, Kaulf, 



ddd. Fronds decompound, herbaceous, a single veinlet and sorus to each final segment. 



31. A. myriophyllum, Spreng. 



32. A. montiver dense, Hook. 



33. A. rhizophyllum, Kunze. 



34. A. cicutarium, Sw. 



dddd. Racbis prolonged into a naked whip-like radicant tail. 



35. A. rutaceum, Mett. 



36. A. rhizophorum, Linn. 



hh. Sori linear, few or several double on the same veins, 

 c. Fronds simple, entire. 



37. A. plantagineum, Linn. 

 cc. Fronds pinnate, pinnae entire. 



38. A. juglandifolium, Lam. 

 39 A. flavescens, Mett. 



40. A. grandifolmm, Sw. 

 4L A. celtidifolium, Mett. 

 ccc. Fronds pinnate, pinnsc uniformly lobed. 



42. A. Shepherdii, Spreng, 

 cccc. Fronds bipinnatifid. 



43. A. costale, Sw. 



ccccc. Fronds varying from bi to tripinnatifid. 



44. A. striatum, Linn. 

 eccccc. Fronds bipinnate. 



45. A. Klotxschii, Mett. 

 ccccccc. Fronds tripinnatifid. 



46. A. radicans, Schk. 



cccccccc. Fronds pinnate, pinnae entire, lobed, or with a partially or quite free lobe on the upper 

 side of the base. 



47. A. duale, Jenm. 



48. A. arboreum, Willd. 

 ccccccccc. Fronds bipinnate. 



49. A. semihastatum, Kunze. 



50. A. monticolum, Jenm. 

 cccccccccc. Fronds bi-tripinnate. 



51. A. Fadyeni, Hook. 

 ccccccccccc. Fronds tripinnate. 



52. A. Franconis, Mett. 



bbb. Sori shortly oblong ; few or several double on the same veins ; involucres vaulted. 

 c. Fronds bipinnatifid. 



53. A. conchatum, Moore. 

 cc. Fronds tripinnatifid. 



54. A. Mans, Kunze. 



55. A. altissimum, Jenm. 

 ccc. Fronds multifid. 



56. A. bruneo-viride, Jenm. 



57. A. Wilsoni, Baker. 



aa. Veins uniting and forming a network next the margin, linear and parallel within. 



58. A. marginatum, Linn. 



1. A. serratum, Linn. — Rootstock erect, forming a fibrous mass ; fronds several or many, shut- 

 tlecock-like, 1-3 or 4ft. 1. 3-6in. w., simple, lanceolate-oblong or oblanceolate, acuminate acute or cus- 

 pidate, gradually or somewhat abruptly reduced below to the very, short margined, triquetrous stipes, 

 subcoriaceous, glossy above and bright green, naked ; crenate or crenate-serrate, and usually somewhat 

 repand : midrib prominently raised, green, the base purple or blackish, keeled beneath ; veins free, 

 close, parallel, spreading at a wide angle from the midrib where they are slightly curved and the ma- 

 jority once-forked, sori linear, l-2in. 1. about 1 li, apart, straight, extending from near the midrib ^ 

 or f to the margin ; involucres flat, narrow, pale, the edge even, — Plum, Fil, t. 124 — Hook. Fil. Exot. 

 t. 70 ; Eat. Fer. N. Am, pi. 3. 



Fiequent on the branches of trees and on exposed rocks, chiefly the former, in moist woods and 

 along the banks of rivers among the lower hills ; principally a lowland species, but reaching spa- 

 ringly to 2,000 or 2,500 ft. alt. Young plants are very deeply serrated, the feature being gradually 

 modified by age. This is the Western representative of the larger and equally common A. nidus, 

 Linn, of the Eastern and Southern Hemisphere.* 



