East america fossil dating

Rated 4.47/5 based on 684 customer reviews

Equisetum is a "living fossil" as it is the only living genus of the entire class Equisetopsida, which for over one hundred million years was much more diverse and dominated the understory of late Paleozoic forests.Some Equisetopsida were large trees reaching to 30 meters tall.In these plants the leaves are greatly reduced and usually non-photosynthetic.They contain a single, non-branching vascular trace, which is the defining feature of microphylls.The name "horsetail", often used for the entire group, arose because the branched species somewhat resemble a horse's tail.Similarly, the scientific name Equisetum is derived from the Latin equus ("horse") seta ("bristle").There may or may not be whorls of branches at the nodes.The spores are borne under sporangiophores in strobili, cone-like structures at the tips of some of the stems. palustre) they are very similar to sterile shoots, photosynthetic and with whorls of branches.

Only four (bogotense, giganteum, myriochaetum, and ramosissimum) of the fifteen species are known to be native south of the Equator.

The lack of MXE in the Poales suggests that there it must play some other, currently unknown, role.

Due to the correlation between MXE activity and cell age, MXE has been proposed to promote the cessation of cell expansion.

The evolutionary distance between Equisetum and the Poales suggests that each evolved MLG independently.

The presence of MXE activity in Equisetum suggests that they have evolved MLG along with some mechanism of cell wall modification.

Leave a Reply