FERNS 



FERNS 



1209 



DDDD. Sporangia numerous, collected in definite serve to indicate not only the relatively great age of 



clusters (sori) . the plant but its slow rate of continuous development, 



8. Cyatheaceae. Mostly tree ferns with sessile or as well. 



short-stalked sporangia in conspicuous receptacles, ree fern s are primarily forest dwellers and occur 



opening obliquely (Fig 1179 Vol II) either as component parts of the dominant forest 



9. Polypodiacese. Ferns ' with stalked sporangia ^ ro ^ h , or ' more commonly, as a sort of thicket or 



AA. Spores of two sorts: minute microspores and con- change; they reach, therefore, their best development, 



spcuous macrospores. (Heterospor- 

 ous.) These spores develop into two 

 sorts of prothalli, those from the micro- 

 spores developing only antheridia, and 

 those from the macrospores only arche- 

 gonia. 



10. Marsiliaceae. Small plants rooting 

 in mud, the Ivs. either quadrifoliate or 

 reduced to mere filamentous petioles: 

 sporangia borne in oval conceptacles on 

 the leaf-stalks. Often aquatic, with the 

 leaves floating on the surface of water in 

 pools or lakes. 



11. Salviniacese. Small or minute plants 

 with the aspect of liverworts, floating on 

 the surface of pools: sporangia in mostly 

 spherical conceptacles. 



The literature on the ferns is very ex- 

 tensive, since they have ever been attrac- 

 tive plants in cultivation. Many of the 

 species have been illustrated in elaborate 

 treatises by Schkuhr, Kunze, Hooker, 

 Greville, Blume, F4e, Mettenius, Moore, 

 and others. Our native species have been 

 illustrated in the two quarto volumes of 

 D. C. Eaton, "The Ferns of North Amer- 

 ica." A valuable summary of the more 

 common fern species is found in Dr. 

 Christ's "Die Farnkrauter der Erde" 

 (1897), and a recent structural and 

 morphological treatment is by Sadebeck, 

 in Engler & Prantl: "Die Naturlichen 

 Pflanzenfamilien." Schneider's "Book of 

 Choice Ferns" is the most complete treat- 

 ise on the species under cultivation. A 

 useful American horticultural manual is 

 Robinson's "Ferns in Their Homes and 

 Ours." An excellent little handbook for 

 the wild species of this country is Under- 

 wood's "Native Ferns and Their Allies." 

 L. M. UNDERWOOD. 



R. C. BENEDICT.f 



Tree ferns. 



The term "tree fern" is applied com- 

 monly to ferns of the family Cyatheaceae, 

 to distinguish them from species of other 

 families of ferns which, for the most part, 

 are not at all arborescent. A compara- 

 tively small number of Cyatheaceae, it is 

 true, have the trunk short, and oblique or 

 decumbent; but in most species the trunk 

 is erect and greatly elongate (commonly 

 3 'to 40 feet high) and the whole plant 

 so unmistakably tree-like in size and pro- 

 portion, that the name "tree fern" is a 

 most appropriate one for the family. The 

 leaves are usually large and are borne in 

 a radiating palm-like crown at the apex of 

 the trunk, or caudex, as it is often called. 

 The trunk itself, in the case of an ordinary 

 mature individual, is marked by numer- 

 ous close-set leaf-scars (Fig. 1487); these 



HI 



f -'- ' 



1- -*. t- 



1487. The trunk of a tree 

 fern. Cyathea arborea. 



both as to species and number of indi- 

 viduals, upon lofty mountains and upon 

 the seaward side of ranges which are 

 drenched constantly by cool moisture- 

 laden winds from the ocean. 



The successful cultivation of tree ferns 

 under glass is predicated upon these facts, 

 although not all the species here men- 

 tioned are horticulturally known in this 

 country. It is found that most species 

 should be grown at a temperature of about 

 60 F. and in a rather shallow soil; that a 

 continuously wet but well-drained sub- 

 stratum is essential; and that in general a 

 tolerably high atmospheric humidity also 

 is requisite for best growth. Very bright 

 sunlight must be guarded against in all 

 but a few species, among these being the 

 common tropical American Cyathea 

 arborea, which grows naturally in rather 

 open places, and C. furfuracea, a native 

 of Cuba and Jamaica which assumes a not 

 unattractive form in drier open situations. 

 As in other groups of ferns, there are cer- 

 tain species which demand unusual care 

 and minor variations of treatment, such 

 as wrapping the trunk in sphagnum as 

 a safeguard against drying out. These 

 special requirements can be determined 

 only by experience. 



The Cyatheaceae are divided technically 

 into three tribes: Thyrsopterideae, Dick- 

 sonieae, and Cyatheae. The first mentioned 

 consists of a single species, Thyrsopteris 

 elegans, Kunze, from Juan Ferndndez. The 

 two latter tribes may be distinguished as 

 follows: 



Sori terminal upon the veins, at or 

 near the margin of the segments; 

 indusia at least bilobed, the outer 

 lip formed of the more or less modi- 

 fied lobule of the leaf Dicksonieae. 



Sori borne upon the back of the veins ; 

 indusium (if present) not formed of 

 the leaf -margin in any part . . Cyatheae. 



The Dicksonieae consist of three genera: 

 Culcita (often known as Balantium), with 

 about six species, all of small stature and 

 nearly devoid of trunk; Dicksonia, with 

 five tropical American species and several 

 hardy Australasian species, the latter not 

 uncommon in cultivation and capable of 

 enduring unusually great extremes of cold ; 

 and Cibotium, with four North American 

 species and several which occur in Asia 

 and the islands of the Pacific. (See under 

 Cibotium and Dicksonia.) 



It is in the Cyatheae, however, that the 

 greatest variety and extremes of leaf form 

 are noted, and consequently the species 

 of this tribe are most highly esteemed in 

 cultivation. They are commonly asso- 

 ciated under three genera: Cyathea, 

 Alspphila, and Hemitelia, distinguished 

 mainly by characters of the indusia. One 



