512 Key to the System of 



ALSOPHILA. 



2141. Trunk tall, but comparatively slender. 



Tree-fern, occupying forest ridges ; trunk of hard texture 

 almost throughout ; frond-stalks prickly-rough, the base 

 of the stalks of decayed fronds for a long while persistent ; 

 fronds extremely large, and particularly broad, bi- or tri- 

 pinnate ; main-rhachis usually pale -brownish ; pinnules 

 mostly elongate-semilanceolar, gradually much narrowed 

 into the acute apex, beneath somewhat greyish, divided 

 towards the base into usually oblique -semilanceolar seg- 

 ments, towards the summit into lobes of more deltoid form; 

 divisions entire or slightly denticulated ; receptacle of fruit- 

 masses beset with minute hairlets ; spore-caselets almost 

 obovate-ellipsoid, their ring jointed, as also in all the now 

 following ferns. Figure 138. " Slender Fern-tree." 



A. australis. 



CYATHEA. 



2142. Trunk very slender. 



Tall, sometimes very much so ; frond-stalks light-colored 

 and rough, those of decayed fronds completely seceding, 

 leaving clear scars ; fronds very large, of rather thin 

 texture, bi- or tri-pinnate ; segments of the pinnules 

 obliquely and often narrowly semi-lanceolar or semi- 

 elliptical, rather conspicuously denticulated or quite 

 indented, the terminal segments confluent ; fruit-masses 

 sparse, roundish ; cover very tender, surrounding only the 

 lower portion of the fruit-masses even in their young 

 state, without any terminal closure ; ring of spore- 

 caselets imperfect. Figure 135. C. Cunningham.!. 



DXCK.SONXA. 



2143. Trunk tall and robust. 



Tree-fern, occupying irrigated valleys ; trunk externally 

 much of soft texture, rough-fibrously coated ; frond -stalks 

 almost smooth ; fronds extremely large, rigid, bi- or tri- 

 pinnate, beneath paler green ; main-rhachis often greenish ; 

 middle pinnas gradually longest ; pinnules mostly elongate- 

 semi-lanceolar in outline, their segments only about twice 

 as long as broad or often still shorter, towards their sum- 

 mit sharply denticulated ; outer valve of the fruit-masses 

 rather firm, greenish, partly formed by a lobe of the seg- 

 ment of the pinnule, semi-globular, deeply hollowed ; 

 inner valve quite membranous, at first lid-like covering 

 the outer; spore-caselets provided with an imperfect ring. 

 Figure 139. " Stout Fern-tree." 



(D. antarctica.) D. Billardierii. 



