30 



THE BOOK OF CHOICE FERNS. 



These so-called generca are now simply regarded as sections of the genus 

 Cheilantlies, and are classed as follows : 



Adiantopsis — Ad-i-ant-op'-sis, Fee. The plants of this section have their 

 involucres distinct, roundish, and confined to the apex of a single veinlet ; 

 the stalks of their fronds are mostly of a glossy nature and of a dark brown 

 colour, similar to those of the generality of Adiantums. The best-known 

 plant in the section is probably C. radiata, usually found in collections under 

 the name of either Adiantum or Adiantopsis radiata. 



Aleuritopteris — Al-eu-ri-top'-ter-is, Fee. In this section the fronds are 

 less finely divided than those of the other three sections of which the genus 

 is formed ; their under-side is more or less densely coated with a white 

 or yellow powder of a ceraceous nature ; their stalks are usually scaly, 

 especially when young ; and the involucres are more or less confluent (not 

 so distinctly separated as in the other sections). C. farinosa., or, as it is 

 commonly called, Aleuritopteris mexicana, is a very good illustration of the 

 distinctive characters. 



Allosorus — All-os-o'-rus, Presl (in part). The plants which by former 

 authorities were given as forming under this name a section of the genus 

 Cheilanthes, are now recognised either as Cryptogramme of E. Brown, or 

 as forming a sub-division of the genus Pellcea., with which they have a much 

 greater affinity. 



EucHEiLANTHES — Eu-clieil-antli'-es (true Cheilanthes)., Hooker. It is in this 

 section that we find the most popularly-known species, with glossy fronds, 

 such as C. micro2)hyUa and C. Sieberi. None of the plants contained in it 

 have the under- surface of their fronds suffused with any powder ; the stalks 

 are sometimes scaly throughout, or more or less scaly only towards the base ; 

 the segments are larger and flatter than in PhysajJteris ; and the involucres 

 are more or less confluent, though never quite continuous. 



Physapteris — Phy-sap'-ter-is, Presl., or Myriopteris — Myr-i-op'-ter-is, Fee. 

 This is the section in which we find the plants with fronds of a tomentose 

 (woolly) nature, most finely divided, their bead-Hke ultimate segments being, 

 in some instances, particularly small — most of them, such as C. myriophylla 

 and C. tomentosa, being among the gems of the most popularly-grown species 

 of Cheilanthes. In nearly all cases the stalks are either woolly or scaly and 

 the involucres confluent, though the latter do not form a continuous line. 



