Monilophyta (Ferns) Summary

Monilophyta (Ferns)

The sporophyte is large and dominant, with true leaves, stems, and roots. They are mostly found in shady, moist places.
Ferns have large leaves called fronds (with vascular tissue) called megaphylls. Young leaves are coiled (crozier).

Key parts include the rachis, blade, pinna, frond, rhizome, root, stipe, pinnule, and fiddlehead or crozier.

Spores are produced in sporangia, usually on the underside of leaves. Some ferns have sporangia on special branches.
Sporangia are usually grouped into sori (sorus), which are covered by an indusium when young.

Sporangium consist of annulus (cells with thick walls), stomium cells (with weak/thin walls), spores (n) produced by meiosis and a stalk that attaches sporangium to leaf.

Spore dispersal requires dry conditions. Thick-walled annulus cells pull against the weak stomium cells, causing the stomium to break and spores to be thrown out of the sporangium.
Spores land on soil and germinate into a green gametophyte (n). Most ferns are homosporous, but some (water ferns) are heterosporous.

The gametophyte, called prothallus, is independent, photosynthetic but short-lived, and limited to moist habitats. It is small, green, and heart-shaped, attached by rhizoids.
Antheridia and archegonia are on the same gametophyte. Ferns still require water for fertilization.
Fern sporophytes and gametophytes live on land.
Both are independent.
Gametophyte need moist conditions. Sporophyte more adapted to land.
Sexual reproduction still requires water to carry male gamete (swimming sperm).
Ferns have been called the ‘amphibians’ of the plant kingdom.

Sporophyte consists of a photosynthetic stem and small, wedge-shaped leaves arranged in whorls around the stem.
Spores are borne in sporangia arranged in a terminal strobilus.
Plants are homosporous but spores develop into small female and male gametophytes.
Represented by one living genus, Equisetum.

Most members are extinct, with only two extant genera: Psilotum & Tmesipteris.
Sporophyte consists of dichotomous branches with small leaf-like appendages not supplied with vascular tissues.
Rhizomes (underground stems) are present.
Fertile aerial shoots bear three-lobed structures called synangia (um).
Synangia develop on tips of short lateral branches and are formed from the fusion of 3 sporangia.
Plants are homosporous.
Spores germinate to give gametophytes without chlorophyll (achlorophyllous), considered to be saprophytic.
Both archegonia & antheridia develop on the same gametophyte (monoecious).