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Asclepias incarnata - L.

Common Name Swamp Milkweed, Swamp Butterfly Weed, Marsh Milkweed
Family Asclepiadaceae
USDA hardiness 3-8
Known Hazards Although no specific reports have been seen for this species, many, if not all, members of this genus contain toxic resinoids, alkaloids and cardiac glycosides[274]. They are usually avoided by grazing animals[274]. The leaves and the stems might be poisonous[20].
Habitats Swamps, wet thickets and shores[43].
Range N. America - Quebec to Manitoba and Wyoming, south to Texas and New Mexico.
Edibility Rating    (3 of 5)
Other Uses    (3 of 5)
Weed Potential Yes
Medicinal Rating    (2 of 5)
Fully Hardy Well drained soil Moist Soil Wet Soil Semi-shade Full sun
Asclepias incarnata Swamp Milkweed, Swamp Butterfly Weed, Marsh Milkweed

Asclepias incarnata Swamp Milkweed, Swamp Butterfly Weed, Marsh Milkweed


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Common names include: rose milkweed, swamp milkweed, Swamp Butterfly Weed, and Marsh Milkweed. The plants have specialized roots for living in heavy wet soils. Some good edible, medicinal and other uses. Bloom Color: Pink, Purple. Main Bloom Time: Early fall, Late summer, Mid summer. Form: Upright or erect.

Physical Characteristics

 icon of manicon of flower
Asclepias incarnata is a PERENNIAL growing to 1.2 m (4ft) at a medium rate.
It is hardy to zone (UK) 3. It is in flower from July to August, and the seeds ripen in September. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees, insects, Lepidoptera (Moths & Butterflies). The plant is self-fertile.
It is noted for attracting wildlife.
Suitable for: light (sandy) and medium (loamy) soils and can grow in heavy clay soil. Suitable pH: acid, neutral and basic (alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry moist or wet soil.



 Bog Garden; Cultivated Beds;

Edible Uses

Edible Parts: Flowers;  Leaves;  Oil;  Seedpod.
Edible Uses: Oil;  Sweetener.

Unopened flower buds - cooked[46, 61, 161]. Tasting somewhat like peas[85]. They can also be dried and stored for later use[183]. Young shoots - cooked. An asparagus substitute[85, 106]. Tips of older shoots are cooked like spinach[85]. Young seed pods, harvested when 3 - 4 cm long - cooked. A pea-like flavour, they are very appetizing[85]. The flower clusters can be boiled down to make a sugary syrup[85].

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.

Anthelmintic;  Carminative;  Diuretic;  Emetic;  Laxative;  Stomachic.

A tea made from the roots is anthelmintic, carminative, diuretic, emetic, strongly laxative and stomachic[4, 61, 222, 257]. The tea is said to remove tapeworms from the body in one hour[257]. It has also been used in the treatment of asthma, rheumatism, syphilis, worms and as a heart tonic[4, 207, 222]. An infusion of the roots is used as a strengthening bath for children and adults[257].

Other Uses

Fibre;  Latex;  Oil;  Pollution;  Stuffing;  Wax.

A good quality fibre is obtained from the bark[46, 57, 61, 95, 112, 169]. It is used in twine, cloth etc[112]. It is easily harvested in late autumn, after the plants have died down, by simply pulling it off the dead stems[112]. The seed floss is used to stuff pillows etc or is mixed with other fibres to make cloth[57, 171]. It is a Kapok substitute, it is used in Life Jackets or as a stuffing material[169, 171]. It is very water repellent. The floss has also been used to mop up oil spills at sea. Rubber can be made from latex contained in the leaves and stems[57]. Pods contain an oil and a wax which are of potential importance[171].

Cultivation details

Experimental Crop;  Industrial Crop: Hydrocarbon;  Management: Hay.

Landscape Uses:Border, Foundation, Massing. Prefers a well-drained light rich or peaty soil[1, 200]. Requires a moist soil and a sunny position, doing well by water[111, 134]. Succeeds on dry soils and on all soil types[112]. Plants are hardy to at least -25°c[187]. A very ornamental plant[1], the flowers are very attractive to butterflies[169]. The flower of many members of this genus can trap insects between its anther cells, the struggles of the insect in escaping ensure the pollination of the plant[207]. Many members of this genus seem to be particularly prone to damage by slugs. The young growth in spring is especially vulnerable, but older growth is also attacked and even well-established plants have been destroyed in wet years[K]. Plants resent root disturbance and are best planted into their final positions whilst small[134]. Special Features:Attractive foliage, North American native, Naturalizing, Wetlands plant, Attracts butterflies, Suitable for cut flowers, Fragrant flowers.


Seed - best sown in a greenhouse as soon as it is ripe in the autumn or in late winter[134, 169]. We have also had good results from sowing the seed in the greenhouse in early spring[K], though stored seed might need 2 - 3 weeks cold stratification[134]. Germination usually takes place in 1 - 3 months at 18°c[134]. As soon as the seedlings are large enough to handle, prick them out into individual pots and grow them on in the greenhouse for their first winter. Plant out when they are in active growth in late spring or early summer and give them some protection from slugs until they are growing away strongly. Division in spring. With great care since the plant resents root disturbance. Pot the divisions up and place them in a lightly shaded position in the greenhouse until they are growing away strongly, then plant them out in the summer, giving them some protection from slugs until they are established.. Basal cuttings in late spring. Use shoots about 10cm long with as much of their white underground stem as possible. Pot them up individually and place them in a lightly shaded position in a greenhouse until they are rooting and growing actively. If the plants grow sufficiently, they can be put into their permanent positions in the summer, otherwise keep them in the greenhouse until the following spring and when they are in active growth plant them out into their permanent positions. Give them some protection from slugs until they are established.

Other Names

If available other names are mentioned here

Found In

Countries where the plant has been found are listed here if the information is available

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it’s worth checking.

This plant can be weedy or invasive. Some reports of weed problems in Nebraska and Wyoming, USA.

Conservation Status

IUCN Red List of Threatened Plants Status : Asclepias incarnata Status: Least Concern.

Related Plants
Latin NameCommon NameEdibility RatingMedicinal Rating
Asclepias asperulaAntelope Horns, Spider milkweed, Trailing Milkweed21
Asclepias brachystephanaBract milkweed00
Asclepias californicaCalifornia Milkweed, Greene's milkweed21
Asclepias currasavicaBlood Flower01
Asclepias decumbens 20
Asclepias eriocarpaWoollypod Milkweed22
Asclepias erosaDesert Milkweed20
Asclepias galioidesBedstraw Milkweed21
Asclepias halliiPurple Silkweed, Hall's milkweed31
Asclepias involucrataDwarf Milkweed21
Asclepias lanceolataPurple Silkweed, Fewflower milkweed21
Asclepias latifoliaBroadleaf Milkweed01
Asclepias mexicana 10
Asclepias ovalifoliaOval-leaf milkweed20
Asclepias pumilaLow Milkweed, Plains milkweed21
Asclepias purpurascensPurple Milkweed21
Asclepias quadrifoliaFourleaf Milkweed22
Asclepias rubraRed Silkweed31
Asclepias speciosaShowy Milkweed32
Asclepias subulataRush Milkweed01
Asclepias sullivantiiPrairie milkweed00
Asclepias syriacaCommon Milkweed, Silkweed, Milkweed32
Asclepias tuberosaPleurisy Root, Butterfly milkweed, Rolfs' milkweed, Indian Paintbrush33
Asclepias viridifloraGreen Milkweed, Green comet milkweed32


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Readers comment

Louie   Thu Dec 19 21:27:45 2002

I'm looking for a plant which best for reducing carbon dioxide indoors, but I couldn't find that information here.

   Fri Aug 21 2009

The table at the beginning of ths section lists the plant as hazardous and may be poisonous. Below however there are edible parts. So is it or not poisonous when eaten fresh or just as a tea? Thanks Robert

David (volunteer)   Fri Aug 21 2009

Thanks for pointing this out, Googling "Aslepias incarnata" and "toxic" it seems the plant is definately toxic. This info must not have been available at the time of writing (a while back). Obviously there has been a tradition of eating it without any ill-effects being noticed, this suggests you'd have to eat a lot for irreversible damage but it may be one of those nasty toxins that slowly build up in the system. With more obscure foods sometimes the science is simply incomplete, I can't find anything saying it is one of those toxins that are destroyed by heat or drying. I would'nt eat much of it on present info.

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