Stolons
are stems that run almost
parallel to the ground, or just below the surface, and can give rise to new plants at the nodes.
Runners
are a type of stolon that runs above the ground and produces new clone plants at nodes at varying
intervals: strawberries are an example. As seen in the potato,
tubers
are modified stems that can store
starch (Solanum sp.). Known to us as the "eyes" on potatoes, tubers develop as the swollen ends of
stolons and contain numerous adventitious or unusual buds. A
bulb
is an adaptation of a stem that
resembles enlarged fleshy leaves emerging from the stem or encircling the stem's base, as seen in the
iris. A bulb serves as an underground storage unit.
160
Figure 105.
Plants are able to flourish in a variety of environments thanks to stem modifications. A ginger
root (Zingiber officinale), a corm from a carrion flower (Amorphophallus titanum), stolons from Rhodes
grass (Chloris gayana), runners from strawberries (Fragaria ananassa), potatoes (Solanum tuberosum) and
red onion bulbs (Allium) are displayed
78
.
Thorns
and
tendrils
are two examples of aerial stem modifications (Figure 106). Tendrils are
thin, twining strands that enable a plant (such as a vine or pumpkin) to climb on other surfaces in
search of support. Roses, Osage oranges, and devil's walking sticks are common examples of plants
with thorns, which are modified branches that resemble sharp outgrowths and serve as a form of
protection

.
Figure 106.
The buckwheat vine (Brunnichia ovata), a weedy plant that climbs with the help of
tendrils, is found in the Southeast of the United States. This one can be seen ascending a wooden stake. (b)
Thorns are modified branches (credit a: modification of work by Christopher Meloche, USDA ARS; credit b:
modification of work by "JonRichfield"/Wikimedia Commons)
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(credit a: modification of work by Maja Dumat; credit c: modification of work by Harry Rose; credit d: modification
of work by Rebecca Siegel; credit e: modification of work by Scott Bauer, USDA ARS; credit f: modification of work
by Stephen Ausmus, USDA ARS)
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