Telome Concept

The concept was proposed by Walter Zimmermann in the 1930s and 1940s, which uses several "elementary processes" to explain how new plant morphologies have evolved and are present in the fossil record. Zimmermann used the architecture of the earliest land plants (i.e. rhyniophytes), and then added "elementary processes" which are quasi-developmental/evolutionary mechanisms that create new and derived plant forms found in the fossil record. Zimmermann proposed that natural selection acted on the “telomes” or distal-most axes of these early plants. Telome Concept was able to explain the increase in complexity of plant form found in the fossil record. This concept or hypothesis lacks solid testing or verification, therefore it is not being referred to as the Telome Theory.

The "telomic processes" proposed include: Over-topping, Planation, Reduction, Recurvation, Syngenesis, and Webbing

Over-topping

Plants evolve from an isotomous branching habit to pseudomonopodial growth, creating lateral axes that are used for photosynthesis and reproduction.

Planation

The three-dimensional branching systems evolve to grow in a two-dimensional or flattened plane. The lateral branches, mentioned above, would growth in an orientation to intercept as much light as possible.

Reduction

The length and frequency of branching is decreased over time, such that terminal branching systems are shortened or compressed

Recurvation

Branch system grow in manner that causes them to curl or orient back toward the main axis. This is found in several Devonian plants, and is exhibited in living horsetail cones.

Webbing

Tissues form in-between the axes of these lateral branches to create a laminate leaf

Syngenesis

Branching system and / or the vascular traces inside stems and leaves fuse together over time. Fusion of sporangia is exhibited in the Psilotales.

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