156 BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 
Plants comparatively small, essentially epiphytic, i. e., on 
trees, mossy rocks or logs, rarely on the ground, herbaceous, both 
as to stems and leaves, never with any sclerenchymatous tissue, 
the mechanical tissue being in the form of collenchyma. 
Stems creeping, covered with clathrate scales. 
Leaves simple, entire (Hecistopteris excepted), the venation 
when divided at all, anastomosing (Hecistopteris excepted) to form 
simple areolae without included veinlets 
Sporangia borne in lines of indefinite extent along the backs 
of some or all of the veinlets (Anetium excepted), often forming 
branching series, sometimes anastomosing, superficial in a few 
species but usually immersed in the leaf substance in distinct 
grooves. Epidermis usually provided with specialized cells, the 
outer walls of which are very greatly thickened. 
These characters, with the exceptions noted, hold true for 
all the species. In habitat the species are all essentially alike, 
except that one species, Antrophyum latifolium, has been recorded 
by Dr. E. B. Copeland as occurring on the soil. Mr. R. S. 
Williams, who has collected a considerable number of the species, 
in the Philippines and in Central and South America, tells me he 
has often found the plants much wilted in the heat of the day but 
apparently not injured on this account. Some of them, at least, 
may often occur in exposed situations, and are probably essentially 
xerophytic. This may appear in the leaf structure. Thus, in 
Vittaria lineata, the leaf may have the epidermis reinforced by 
several tiers of thick-walled cells without chlorophyl, presumably 
to aid in conserving the water supply. This, the commonest 
American species of the tribe, occurs in exposed situations, epi- 
phytic usually on palms. 
The herbaceous character is a uniform feature. In Diel’s 
treatment of the tribe, as presented in Engler and Prantl, Die 
Natiirlichen Pflanzenfamilien, several species of an essentially 
woody nature are included, and these in the simplest and most 
tenuous of all the genera, Monogramma. These woody plants are 
mostly American species, which Dr. H. Christ has better sepa- 
rated as a distinct genus, following Presl, i. e., Plewrogramma 
Presl. There is ample evidence to show that they are not only 
not to be included in Monogramma, but that they may not even 
be retained in the tribe Vittarieae. They are hard, tough little 
plants with a strong development of sclerenchyma fibers in the 
