CHAPTER XXXIII 



CYATHEACEAE (EXCL. DICKSONIEAE) 



In the strict sense only three genera should be included under this title, viz. 

 Alsophila, Hemitelia, and Cyathea, which are mostly Ferns of dendroid habit, 

 with chafify scales, and they all possess gradate sori. But as already suggested 

 Lophosoria and Metaxya, which are technically Simplices, are so closely allied 

 to Alsophila as to have been included by most systematists in that genus : 

 nevertheless, following Presl, they are best placed as distinct genera, and 

 even ranked as an intermediate family of Proto-cyatheaceae. On the other 

 hand, Woodsia, Diacalpe, and Peraneina have always been held as related to 

 the Cyatheaceae: it will be seen later that they show gradual steps of 

 character which can only indicate a further phyletic progression towards 

 a mixed sorus. The family of the Cyatheaceae forms in fact a middle term 

 of transition from the superficial Simplices such as the Gleicheniaceae, 

 through a gradate phase which they represent, to the mixed type of sorus. 

 Parallel with this progression in soral characters go also other features, both 

 vegetative and propagative, which confirm the comparisons between these 

 naturally related Ferns. A strong phyletic interest thus attaches to the 

 Cyatheaceae (excl. Dicksonieae). 



The three genera include species of varying size. Though such Tree-Ferns 

 as Alsophila excelsa and Cyathea inedullaris rise with a single trunk to 

 a height of 60 or even 80 feet, many are of low stature. Some have 

 numerous lateral branches, which are related to the main axis and the leaf- 

 bases exactly as are the runners in Lophosoria (see Fig. 547). This has been 

 worked out in Alsophila aciileata by Stenzel {Nova Acta d. D. Akad. 1861), 

 who demonstrated the vascular connections and showed in the branches 

 a transition through solenostely to dictyostely, as it is seen in the runners 

 of Lophosoria. The suggestion thus comes clearly, from the comparison of 

 Gleichenia, Metaxya, and Lophosoria with Alsophila, that the upright habit is 

 derivative from the creeping rhizome. The result of such branching as is 

 seen in A. aculcata and Cyathea niexicana is a more or less shrubby habit. 

 But most Cyatheoids have the single columnar trunk, though it may 

 occasionally bifurcate (compare Frontispiece to Vol. I). The continuity of 

 the massive pith upwards into the two equal limbs of such a fork indicates 

 that they originated by dichotomy (Fig. 556). A transverse section of a large 

 stem low down also demonstrates how great a proportion of the apparent 

 bulk of the columnar stem is due to the massing of adventitious roots, which 

 gives added mechanical strength to a stem itself incapable of growth in 



