The Evolution of Plant Stems in the Earth’s History
Plant life developed in the water, and this process took over three billion years. Only relatively recently - speaking in terms of the Earth’s history - when the atmosphere’s oxygen content had reached suitably high levels, terrestrial environments were colonized by plants. The so-called “Step on land” took place about 450 million years ago on permanently humid sites in coastal environments. At that time, the Earth generally had a warm climate. Only some spores, fragments of cuticles and epidermis are early witnesses from this period.
KeywordsVascular Bundle Land Plant Secondary Growth Secondary Xylem Sieve Tube
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