Lepidodendron Temporal range: Carboniferous |
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The strobilus of Lepidodendron | |
Scientific classification | |
Kingdom: | Plantae |
Division: | Lycopodiophyta |
Class: | Isoetopsida |
Order: | Lepidodendrales |
Family: | Lepidodendraceae |
Genus: | Lepidodendron |
Species | |
See text |
See text
Lepidodendron — also known as scale tree — is an extinct genus of primitive, vascular, arborescent (tree-like) plant related to the lycopsids (club mosses). They were part of the coal forest flora. They sometimes reached heights of over 30 metres (100 ft), and the trunks were often over 1 m (3.3 ft) in diameter. They thrived during the Carboniferous Period (about 359.2 ± 2.5 Mya (million years ago) to about 299.0 ± 0.8 Mya) before going extinct. Sometimes erroneously called "giant club mosses", they were actually more closely related to today's quillworts than to modern club mosses.
The name Lepidodendron comes from the Greek lepido, scale, and dendron, tree.
Lepidodendron had tall, thick trunks that rarely branched and were topped with a crown of bifurcating branches bearing clusters of leaves. These leaves were long and narrow, similar to large blades of grass, and were spirally-arranged. The vascular system was a siphonostele with exarch xylem maturation.
The closely packed diamond-shaped leaf scars left on the trunk and stems as the plant grew provide some of the most interesting and common fossils in Carboniferous shales and accompanying coal deposits. These fossils look much like tire tracks or alligator skin.
The scars, or leaf cushions, were composed of green photosynthetic tissue, evidenced by the cuticle covering and being dotted with stomata, microscopic pores through which carbon dioxide from the air diffuses into plants. Likewise, the trunks of Lepidodendron would have been green, unlike modern trees which have scaly, non-photosynthetic brown or gray bark.