The Fern botany, and learn about a fern frond that grows in a garden?

Ferns neither form seeds nor do they produce flowers, but have a unique life cycle. The correct name for the actual ferns plant is sporophyte and this simply means spore-forming generation.

The small spores grow in capsules on the underside of the fronds. The spores are formed through division meaning that they only have 50% of chromosomes (haploid). When the spores are ripe they are pushed out of the capsules and captured by the wind. They are light and blown into new positions were they will quickly settle and germinate. From here on they will be called gametophytes.

The prothallium grow from a germinating gametophyte. The prothallium is very flat and tiny, has lobes and also has half a set of chromosomes. Prothallia can photosynthesize as normal leaves do. The prothallium anchors itself firmly in the ground using root-like, hair shaped growths called Rhizoids.

The sexual organs are formed on the underside of the prothallium. Female cells (archegonia) develop in the multi-cellular region under the notch. The ova is contained in the lower section and is contained in the prothallium tissue. The antheridia (male cells) develop between the rhizoids nad will produce spermatozoa which swim vigorously towards the ova. Fertilization will only happen if the prothalliumis wet - due to rainfall or dew.

A zygote is created when the sperm and the ova fuse together. The zygote will have the full chromosome set and it starts producing more cells creating an embryo. The new fern plant develops from this multi celled embryo. The prothallium will later wither and die when the new plant is large and can survive independently.

Spore, Sporangia, Sori : what do all these things have to do with ferns

Different fern species have different spore and sporangia shapes. Sporangia normally cluster together forming structures known as sari. The sori are protected by growths on the leaves, by hairs or by scales. Pseudo-indusia occur in maidenhair fern or in Pteris.

A sori is usually circular shaped such as in Polypodium, or kidney shaped such as Neprolepis. Some form urn shaped indusia for example Davallia. Blenchnum sori which have fascinating shapes which run along the narrow feathers close to the central ribs.

What is a fern frond?

A frond can be defined as the divided leaves of the ferns and they have many small feathery sections that grow from a central leaf stem, rob or rhactus.

  • Single feathered (pinnate) fronds grow from the main lef rib. They are individual and undivided feathery leaves. An example would be Nephrolepis.

  • Double, triple or multi feathered fronds (bipinnate) have feathers which are divided more than once. Perfect examples include Polystichum tsus-simense.

  • Divided fronds involves the leaf division failing to reach as far as the central leaf rib for example Phlebodium aurem.

  • There are also hand-shaped ferns or lobed shaped ferns. Undivided leaves are common among Asplenium and Polypodium.

Fronds come in interesting shapes and sizes. Some leaves will have curly ends, some have varying gradations of feather on the same plant while some have completely unrelated shaped leaves.