How did Megaphyll leaves evolve?

According to the telome theory, megaphylls evolved from the three-dimensional lateral branches of early vascular land plants in a hypothetical series of three transformations; first, the formation of determinate lateral branches (overtopping); second, the development of ‘flattened’ branch systems (planation); and third …

How has the fern leaf evolved?

Fern leaves are shaped the way they are because each species has adapted or changed over time to better suit its particular environment. That’s all thanks to evolution. Some ferns are small and grow on other plants in wet places, while others are tall and tough. There are the tiny, soft fronds of maidenhair ferns.

How and when did ferns evolve?

The ferns and their relatives first appear in the fossil record some 360 million years ago in the late Devonian period. They diversified into many of the modern fern families and species during the “great fern radiation” of the Cretaceous period, from 145 to 66 million years ago.

Where are megaphylls found?

Megaphylls are seen in ferns and more derived vascular plants. In addition to photosynthesis, leaves play another role in the life of the plants. Pine cones, mature fronds of ferns, and flowers are all sporophylls—leaves that were modified structurally to bear sporangia.

Do ferns have microphylls?

Ferns are an ancient group of around 12,000 vascular plants. They similar to ferns but have unique leaves called ‘microphylls’ which have only a single vein. Fern fronds are the leaves of ferns. They are a major organ of a fern and range significantly between species.

Do ferns have seeds?

Ferns generally reproduce by producing spores. However, unlike flowering plants, ferns do not have flowers or seeds; instead, they usually reproduce sexually by tiny spores or sometimes can reproduce vegetatively, as exemplified by the walking fern.

Do ferns produce seeds?

Do ferns have Megaphyll?

If ferns are considered a monophyletic group (Figure 1), then all fern leaves are considered to be megaphylls or at least derived from megaphyllous ancestors. Megaphylls then are present in seed plants and ferns and there are several competing theories regarding their evolution and origin.

What is Megaphyll fern?

A type of foliage leaf in ferns and seed plants that has branched or parallel vascular bundles running through the lamina. The megaphylls of ferns are large pinnate leaves called fronds. A megaphyll was formerly called a macrophyll. Compare microphyll.

Where are Microphylls found?

The clubmosses and horsetails have microphylls, as in all extant species there is only a single vascular trace in each leaf. These leaves are narrow because the width of the blade is limited by the distance water can efficiently diffuse cell-to-cell from the central vascular strand to the margin of the leaf.

How are Microphylls and megaphylls different?

Microphylls are defined as leaves of small size, with simple venation (one vein) and associated with steles that lack leaf gaps (protosteles). By contrast, megaphylls are defined as leaves of generally larger size, with complex venation and associated with leaf gaps in the stele [3].