CHAPTER X 



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CHRISTMAS FERN 



Polystichum acrostichoides. 



Rootstock creeping, chaffy: scales pale brown, lanceolate or 

 ovate, acuminate, slightly ciliate: leaves clustered at apex of 

 rootstock: roots springing from rootstock or extreme bases of 

 petioles. 



Leaves ascending, five to twenty-seven inches long, two and 

 four-fifths to four and four-fifths inches broad, imperfectly ever- 

 green; in autumn prostrated, the fertile parts of sporophylls 

 usually withering. 



Petioles shorter than blades, two to six and two-fifths inches 

 long, toward base dark, often reddish or lighter brown, above 

 green, somewhat flattened or furrowed on face, turgid at base, 

 chaffy: scales numerous, pale brown, ovate or lanceolate, acu- 

 minate, ciliate: fibrovascular bundles four or five; the two 

 anterior largest, ovate-wedge-shaped or suboval in section, or 

 slightly hollowed on one or both sides; the others ellipsoidal or 

 roundish in section. 



Blades rigid, lanceolate, pinnate; apex pinnatifid, becoming 

 serrate or serrulate at tip, subacute or acute or acuminate : pinnae 

 mostly approximate or in sporophylls distant, alternate or oppo- 

 site, mostly subsessile or very short-stalked, obtuse or acute or 



