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FLOEA OF THE DISTRICT OF COLUMBIA. 55 



6. CHEILANTHES Swartz. Lip-fern. 



1. Cheilanthes lanosa (Michx.) Watt. 



Earthy crevices of cliffs or rocky bluffs; rare; vicinity of Great Falls (both sides of the 

 river) and near Chain Bridge. Summer. Eastern U. S. {0. vestita Swartz.) 



7. PELLAEA Link. 



1. Pellaea atropurpurea (L.) Link. Cliff-brake. 



Crevices of dry sunny cliffs or on walls, preferring limestone; several scattered. 

 stations, abundant in only one or two localities. Summer. N. Eng. to Minn., the 

 Mexican border, and Fla. 



8. ADIANTTJM L. Maidenhair. 

 1. Adiantum pedatum L. 



Rich, well-drained, rocky, deciduous woods and shaded hillsides; common. Sum- 

 mer. Most of temperate N. Amer., the western form differing subsneeincallv 



9. CAMPTOSORTJS Link. 



1. Camptosorus rhizophyllus (L.) Link. Walking fern . 



Shaded mossy rocks in cool situations; several localities along the Potomac, prin- 

 cipally above Cabin John; also at Laurel; rare. Que. to Ga., westward. 



10. POLYSTICHUM Roth. 



1. Polystichum acrostichoides (Michx.) Schott. Christmas fern. 



Moist woods and cool shady banks; abundant. About June first. Eastern N. Amer. 

 (Aspidium acrostichoides Swartz.) 



A colony is shown in plate 12. 



11. ANCHISTEA Presl. 



1. Anchistea virginica (L.) Presl. Chain fern. 



Swamps; infrequent, the known localities all in the eastern part of the range. Late 

 summer. Eastern N. Amer. (Woodwardia virginica J . E. Smith.) 



12. ASPLENITJM L. Spleenwort. 



Blades pinnatifid, or pinnate only near the base, the apex slender, long-attenuate. 



Stipe brown below, green above; rachis green 1. A. pinnatifidum 



Stipe and rachis dark purplish brown 2. A. ebenoides. 



Blades 1-3 times pinnate, the apex not long-attenuate. 

 Stipes and rachises reddish or purplish brown throughout; blades linear, once pin- 

 nate only. 

 Fertile leaves rigidly erect, 20-40 cm. long; sterile leaves short, spreading; seg- 

 ments more or less auricled 3. A. platyneuron . 



Fertile and sterile leaves alike, all spreading, much narrower, 7-20 cm. long; seg- 

 ments not auricled 4. A. trichomanes . 



Stipes green from a dark brown base; rachises green; blades 2 or 3 times pinnate or 

 pinnatifid, more or less triangular 5. A. montanum. 



1. Asplenium pinnatifidum Nutt. 



Crevices and earth pockets of shaded cliffs; Virginia shore of the Potomac Be vera 1 

 miles below Great Falls; very rare. Summer. Conn, to G a., westward. 



2. Asplenium ebenoides R. R. Scott. Scott's spleenwort. 

 Crevices of shaded rocks; two records, Plum m era Island and Virginia shore of the 



Potomac near Little Falls. Summer. Vt. to Va., Mo., and Ala.; abundant only in the 

 last state, where it is self-perpetuating. 



