John Clayton Chapter of the Virginia Native Plant Society’s
Wildflower Spot – July 2008
SWAMP MILKWEED
Asclepias incarnata
These deep
pink flowers in wide clusters on five-foot stems are magnets
to butterflies, which find their faint vanilla scent
irresistible. Swamp milkweed is one of the best attractors
of the Monarch butterfly which feeds on the flowers and lays
its eggs on the plants. The long and narrow opposite leaves
provide a ready food source for the caterpillars. After a
long blooming period, from June through August, upright thin
pods are produced which split open in the fall, releasing
seeds attached to silky hairs that act as parachutes to
carry the seeds on the currents of the wind.
Unlike other members of the
milkweed group, this species does not have milky sap.
They have specialized roots for living in heavy wet
soils, and the thick white roots are adapted to live in
environments low in oxygen. Swamp milkweed prefers
moist open areas and is typically found growing wild
near the edges of ponds, lakes, open ditches and low
areas.
The plant is
found in every county in Virginia, growing easily in full
sun and moist soil in local gardens. Use swamp milkweed at
the back of perennial borders, and along pond and stream
banks. A number of cultivars are available in colors from
white, soft pink-purple to dark purple. The flowers can be
cut for a long-lasting display in the home, and the seedpods
can be used for winter arrangements.
On an
expedition to Utah in 1850, a traveler reported that the
Pueblo Indians rub the stems to separate the fibers, to make
beautiful and very strong fishing lines and fine sewing
thread. A decoction was used for various medicinal
purposes. Although American colonists used swamp milkweed
for asthma, rheumatism, worms, and as a heart tonic, the
plant is potentially toxic.
Written by Helen Hamilton, president of the John Clayton
Chapter of the Virginia Native Plant Society
