DIVISION PTERIDOPHYTA 
By Lucr—=N Marcus UNDERWOOD 
Terrestrial, epiphytic, or rarely aquatic plants, manifesting in their life-his- 
tory two well-marked phases of growth, the so-called alternation of genera- 
tions: (I) The SporopHyts or asexual plant, usually differentiated into root, 
stem, and leaf, having well-developed fibro-vascular tissues and producing 
spores asexually which are either minute and similar (homosporous series) or 
are of two unlike sorts called microspores and megaspores (heterosporous 
series). The spores germinate to form: (II) The GAMETOPHYTE or sexual 
plant (prothallium); in the homosporous series this is a non-vascular thalloid 
(or tuberous) structure, either chlorophyl-bearing and terrestrial or epiphytic, 
or subterranean and usually devoid of chlorophyl; in the heterosporous series 
it consists of much-reduced prothallia of two sorts, the one rising from the 
microspores and producing only male reproductive apparatus, the other rising 
from the megaspore and producing only female reproductive organs. 
Sex-apparatus consisting of antheridia in which ciliate sperms are pro- 
duced, and archegonia in which normally a single egg is developed. Fertili- 
zation consists in the union of a sperm and an egg from which the sporophyte 
develops, becoming ultimately the plant commonly known as a fern, club-moss, 
or horse-tail. 
Order OPHIOGLOSSALES 
By LucigN Marcus UNDERWOOD AND RALPH CURTISS BENEDICT 
Sporophytes herbaceous, consisting of a somewhat tuberous rhizome, with 
fibrous usually fleshy roots and one or several leaves. Leaves erect or in- 
flexed in vernation, non-articulate, consisting of a basal commonstalk bear- 
ing at its apex an entire or divided sterile lamina and usually only one erect 
sporangiophore (1-17 and pendent in Cheivoglossa); sporangiophore (sporophy1) 
stalked, spicate or paniculate. Sporangia developed from a group of epidermal 
and subepidermal cells (eusporangiate), in 2 rows, the walls many cells thick, 
transversely dehiscent. Spores uniform (homosporous), triplanate, ephemeral, 
yellow. 
Gametophytes (prothallia) hypogean, tuberous, usually devoid of chloro- 
phyl and associated with an endophytic mycorhiza. 
(A single family :) Fam. 1. OPHIOGLOSSACEAE. 
VoLUME 16, Part 1, 1909] 1 
