CHARACTERS OF TRIBES AND GENERA. 241 



Receptacles more or less elevated. Indusium calyciform, 

 semi-calyciform or lateral (scale like), or absent or repre- 

 sented by numerous articulate hairs. 



OBS. The plants constituting this tribe (together with 

 those of the genus Dicksonia as here restricted) are truly 

 the giants of the Fern race, their erect arboreous stems 

 often attaining the height of 50 or more feet, and having a 

 crown of decompound (rarely simple or simply pinnate) 

 fronds, sometimes 20 feet in length, the bases of their stipes 

 being either articulated with the stem and, when mature, 

 separating at the articulation, the point of attachment 

 being afterwards indicated by scars of an oblong rhomboid 

 form, spirally arranged round the stem ; or more or less 

 of the lower part of the stipes remain permanent and 

 become indurated, forming part of the solid structure of 

 the stem, which is often much increased in thickness by 

 the production of numerous outgrowing aerial, wiry, black 

 roots, forming a coating from a few inches to a foot in 

 thickness. 



The species are widely distributed, chiefly within or near 

 the tropics, the number being nearly equal in the old and 

 new worlds. They love shade and solitude, and in humid 

 regions within the tropics are found at elevations of from 

 3,000 to 6,000 feet, often in ravines. In Sikkim, Hima- 

 laya, the tribe is represented by eight or nine species, all 

 of which are to be found within three miles of Bungbee. 

 The stems often branch into many crowns. About a dozen 

 are distributed throughout the islands of the Pacific Ocean, 

 their southernmost limit being Tasmania, New Zealand, 

 and Norfolk Island, where they grow at a lower elevation 

 than within the tropics. Also several new species have 

 recently been discovered in the Bellenden Ker range of 

 mountains, Queensland. 



