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Plants3 - in such a way that one branch appeared to be the...

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Plants The zosterophyllophytes were an important early Devonian group that is often mentioned as ancestral to the lycophytes. These plants had small leaf-like ennations that projected from the stems. Ennations are not considered to be leaves since they contain no vascular tissue as is found in leaves. Sporangia in this group were not located on the ends of stems, but rather along the sides of the stems, a feature also seen in lycophytes. Sawdonia , shown below, a leafless Devonian plant covered with spiny projections, is a member of this group. The trimeophytes were larger plants of the early-middle Devonian. Some trimerophytes are thought ancestral to the sphenopsids and progymnosperms of the later Devonian. Unlike the rhyniophytes (such as Rhynia ) and the zosterophyllophytes, trimerophytes did not produce equal (dichotomous) branches. Instead they branched
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Unformatted text preview: in such a way that one branch appeared to be the central stem and the other a side shoot. The Lycophytes Plants belonging to the division Lycophyta, have their sporangia organized into strobili (sing.: strobilus). Leaves that contained vascular tissue are another major advance for this group. The major fossil groups of lycophytes are the lepidodendrids and sigillarids, often referred to as the arborescent lycopods because they usually were large trees. During the middle Devonian lycophytes retaind their herbaceous habit, but also began to grow taller, more than a few meters high at first, and developed the capability for secondary growth to produce wood , allowing the plants to grow still taller. Modern lycophytes lack secondary growth and are entirely herbaceous....
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Plants3 - in such a way that one branch appeared to be the...

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