Published by the authors. Class Ophioglossopsida Eusporangiate and homosporous. Two species of Ophioglossum occur on Guam but both are uncommon. Class Marattiopsida Eusporangiate and homosporous. Sporangia borne on backs of ordinary fronds, as in most Filicopsida.
Photosynthetic gametophytes resemble thallose liverworts.
Angiopteris evecta is a giant fern found on stream banks in southern Guam. Sometimes the sori have a covering called an indusium. Photosynthetic gametophytes are generally thin flakes , sometimes heart-shaped, with archegonia and antheridia borne on the undersides. Look for fern gametophytes among mosses on wet walls and tree trunks, soil, flowerpots, etc . If the archegonia develop determinate sporangia, the plant is a liverwort, if they develop a big, indeterminate sporophyte, it s a fern.