A "tall tree" generally reaches a height of 40 to over 100 feet.
To further elaborate:
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General Height: Most trees considered "tall" fall within the 40-100+ foot range. This is a broad categorization and many species commonly achieve these heights.
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Exceptional Heights: Some tree species, notably Redwood trees ( Sequoia sempervirens ), can far exceed this range.
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Record Holders: The tallest known living tree is a Redwood named Hyperion, measuring approximately 380 feet tall.
In summary, while "tall tree" is a relative term, it typically refers to trees between 40 and 100+ feet in height. Some species, like redwoods, can grow much taller.