identical — plant. The common potato and
true yam are such swollen underground stem
tips called tubers, while the sunchoke and
ginger “root” are horizontal underground
stems called rhizomes.
Leaves Leaves specialize in the production of
high-energy sugar molecules via
photosynthesis, a process that requires
exposure to sunlight and a good supply of
carbon dioxide. They therefore contain very
little storage or strengthening tissue that
would interfere with access to light or air, and
are the most fragile and short-lived parts of
the plant. To maximize light capture, the leaf
is flattened out into a thin sheet with a large
surface area, and the photosynthetic cells are
heavily populated with chloroplasts. To
promote gas exchange, the leaf interior is
filled with thousands of tiny air pockets,
which further increase the area of cells
exposed to the air. Some leaves are as much