Common Name: Showy Milkweed

General Information

Asclepias speciosa is an erect, herbaceous perennial plant with a deep Tproot; it produces a cluster of very stout, unbranched stems 60 -100cm tall[, , ].
This species was widely used by the native North Americans as a food, medicine and source of materials. It has a very good potential for improvement through selection to produce an excellent crop plant. It is also grown as an ornamental, valued especially for its flowers which attract butterflies to the garden.
The plant is widely tolerant to habitat and is becoming weedy in cultivated fields, roadsides, railway embankments etc within its native range. It has escaped from cultivation by means of its seeds, and has become naturalised in cultivated ground and dry grassland in various parts of Europe[].

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. They are only toxic if eaten in large quantities, causing vomiting, stupor, weakness and spasma[, ].
The plants are usually avoided by grazing animals[].

Botanical References

, ,

Range

Western N. America - British Columbia to Manitoba, south to California, New Mexico and Texas

Habitat

Prairies, in sandy and loamy, usually moist soils[]. Naturalised in cultivated ground and dry grassland in various parts of Europe[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Perennial
Height	0.75 m
Pollinators	Bees, Insects, Lepidoptera
Self-fertile	Yes
Cultivation Status	Ornamental, Wild

Cultivation Details

Prefers a well-drained light rich or peaty soil and a sunny position[, , ]. Grows well in poor, dryish, gravelly soils[]. Established plants are drought tolerant[].
A very ornamental plant[], it is closely related to Asclepias purpurascens[]. The roots can spread quite freely when the plant is in a suitable position[].
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[].
Plants resent root disturbance and are best planted into their final positions whilst small[].
The flower of many members of this genus can trap insects between its anther cells - the struggles of the insect in escaping (especially bees and wasps) pulls with it the pollinium (sacs of pollen) which are then transported to the next flower and deposited there, ensuring pollination of the flower[, ].

Edible Uses

Flower buds - raw or cooked[, ]. They taste somewhat like peas[]. They can be used to thicken soups[].

Young shoots and leaves - cooked[, , , , ]. An asparagus substitute[, ]. One report says that they should not be eaten raw[], whilst another says that the young spring shoots were eaten raw by some native American tribes[].
Tips of older shoots are cooked like spinach[, ].
One recipe suggests you parboil the leaves or young shoots for three minutes, then discard the bitter water and replace with clean boiling water. (Cold water tends to fix the bitterness.) You can repeat this process p to three times to fully leach any bitterness (and many of the nutrients[]), then cook the leaves for 15 minutes before seasoning them. A pinch of soda can be added during cooking to break down the fibe and improve flavour[].

Young seed pods, 3 - 4 cm long - raw or cooked[, ]. Very appetizing[]. The immature pods are peeled before being eaten[].

Flower clusters can be boiled down to make a sugary syrup[] or they can be eaten raw[, ].

Seed - raw[, ].

The seed contains up to 20% of an edible semi-drying oil[].

A chewing gum can be made from the latex contained in the stem and leaves[, , , ].

Root[]. No further details are given, but another report says that the root can be poisonous in large quantities[].

Medicinal

The latex is used as a cure for warts[, ]. The latex needs to be applied at least once a day of a period of some weeks for it to be effective[]. The latex has antiseptic properties and has been used to treat skin sores, cuts and ringworm[].

A decoction of the plant tops can be strained and used to treat blindness and snow-blindness[].

The root is either chewed when fresh, or dried, ground into a powder then boiled, and used in the treatment of stomach ache[]. A decoction of the roots has been used in small doses to treat venereal diseases and also to treat coughs, especially from TB[]. A poultice of the mashed roots has been applied to rheumatic joints[]. Some caution should be employed when using the root since there is a report that it can be poisonous in large quantities[].

Other Uses

A good quality tough fibre is obtained from the bark[, ]. It is used in twine, coarse cloth, paper etc[, ]. Yields of 1356kg per hectare have been obtained from wild plants[].The fibre is 10 - 45mm long[]. It is easily harvested in late autumn, after the plants have died down, by simply pulling it off the dead stems[, ]. When making paper, the stems can be retted by leaving them in the ground until they are dry in the winter or they can be harvested in late summer, the leaves removed and the stems steamed to remove the fibre[]. The stems are then cooked for two hours with lye and pounded with mallets[]. The paper colour varies from white to creamy green depending on how the paper is made[]. If the stems are used in the summer the latex will often find its way onto the fibres and is hard to remove[].

The seed floss is used to stuff pillows etc, or is mixed with other fibres to make cloth[, ]. It has also been used as a baby's nappy[]. The seed floss is a Kapok substitute, used in Life Jackets or as a stuffing material[]. It is very water repellent. The floss has also been used to mop up oil spills at sea. Yields of 1368kg per hectare have been obtained from wild plants[].

Rubber can be made from latex contained in the leaves and the stems[, , ]. The yield is up to 3%[]. The latex contains 0.1 - 1.5% caoutchouc, 16 - 17% dry matter and 1.23% ash[]. Total yields of 197kg from wild plants and 897kg from cultivars per hectare have been obtained[].

Pods contain an oil and a wax which are of potential importance. The seeds contain up to 20% of an edible semi-drying oil[].

A green dye is obtained from the flowers and leaves combined[].

Propagation

Seed - best sown in a greenhouse as soon as it is ripe in the autumn or in late winter[, ]. We have also had good results from sowing the seed in the greenhouse in early spring[], though stored seed might need 2 - 3 weeks cold stratification[]. Germination usually takes place in 1 - 3 months at 18°c[]. 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..This species produces deep taproots which makes transplanting very difficult[]. Trying to divide it will probably be equally difficult[].
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.