Simple questions can be the most intriguing. We will ponder the answer to the question: Are leaves alive? In so doing, we will discover leaves were not created equal.
Consider deciduous trees (trees that seasonally lose their leaves). In autumn their leaves change color as their petioles detach. The leaves then fall to the ground. The tree does not die with the loss of its leaves.
A first impression might be that leaves are alive in the same sense that fingers are. However, fingers are not discarded seasonally. So could it be leaves more closely resemble fingernails, which humans clip regularly?
Like Fingernails? Or Are Leaves Alive?
No. Fingernails, devoid of internal structure, are almost 100 percent pure keratin – a protein. Leaves, on the other hand, are made up of cells containing DNA. This clearly indicates leaves initially are alive. They are fragile and thus easily damaged, necessitating regular replacement. There is no pain when they are lost, since they possess no pain sensors. Plants are not sentient creatures. They have no conscious awareness.
But leaves are generally replaceable. Can they be alive in additional ways? The answer is yes! Consider two examples.
Mother of Thousands
The Bryophyllum daigremontianum or Mother of Thousands plant produces plantlets along its leaf margins. Hence its leaves not only feed the plant, but are in part responsible for its propagation. Notice the excellent close-up seen in this image.
But is it only while attached that leaves live? Not always. Consider the African violet.
African violets can be propagated through seed, but more often they are propagated by means of a leaf. The stem of a leaf is inserted in water, moist vermiculite, or perlite. In a matter of weeks, it has rooted and tiny new leaves emerge at the base to produce a new plant. At that point, it is transplanted into an appropriate soil mix.
To press the matter even further, I once used a leaf to propagate a new violet, then because it was so successful, I cut the leaf off above the stem! One more generation saw a tiny fraction of that same leaf producing yet an additional plant!
Leaves are responsible for more than food manufacture. They sometimes are part of the plant’s reproduction. And always, transpiration occurs in the leaves. That is, they are part of the plant’s breathing process. Truly leaves are remarkable, and yes, they are most certainly alive.