C 
CLASS I. 
PTERIDOPHYTA. 
ryptogamic plants with stems, leaves and roots containing vas- 
cular tissues. Spores develop into small, mostly flat green pro- 
thallia, which bear archegonia and antheridia. 
A. 
B. 
Stems short, unbranched; fronds large, well-developed, with sporangia on the 
back or margins. 
1. Fronds not circinate in vernation. Sporangia formed of many epidermis- 
cells, regularly 2-valved, borne on a separate part of the frond. Prothallium 
subterranean, tuberous, monoecious ........ I. OPHIOGLOSSACEAE. 
Fronds circinate in vernation, mostiy pinnate. Sporangia formed of one 
nw 
epidermis-cell, borne in clusters on the back or margins of the frond, 
provided with an elastic ring, opening transversally. Prothallium flat 
SLECN PIMONOCCIOUSN eo cuiaie ote ha eee Ree teatro II. POLYPODIACEAE. 
Stems erect, hollow, jointed, mostly with numerous verticillate branches; 
leaves reduced to toothed sheaths at the joints. Sporangia borne beneath shield- 
shaped leaves, which form a terminal spike. Prothallium flat, very small, 
GIOACTONEN Eyer d, Uooucl he oie oleh beDen en Oioleres amo tsoes. 5 III. EQUISETACEAE. 
Stems creeping, branched; leaves small, simple, crowded or in ranks. Sporangia 
solitary in the axils of the leaves. 
1. Spores uniform. Prothallium subterranean, tuberous. [V. LYCOPODIACEAE. 
2. Spores partly macrospores, partly microspores. Prothallium minute, few- 
CEUTIET OS SB ae eee GoeNG & ean opt ttnaenren seh wee V. SELAGINELLACEAE. 
Stem a fleshy corm with long, subulate leaves; the spore-bearing leaves with 
sporangia in the dilated bases. Macrospores and microspores. Prothallium 
TINMU Lene Ew CELT AT mapianiaiy ac sige hey Scouse) On eik su) ee VI. ISOETACEAE. 
Order I. OPHIOGLOSSACEAE R. Br. (By O. GELERT). 
Only the following genus in the area: 
1. BOTRYCHIUM Sw. 
Frond consisting of a sterile foliaceous and a fertile spicate part, 
both more or less pinnate. 
i, 
Sterile part of the frond sessile or short stalked, attached at or above the 
middle of the stalk. 
A. Fertile part of the frond long stalked exceeding the sterile part .. . B. Lunaria. 
Flora Arctica. 1 
