Asclepias fascicularis

Asclepias fascicularis is a species of milkweed known by the common names narrowleaf milkweed and Mexican whorled milkweed. It is a perennial herb that grows in a variety of habitats.

Description

A perennial milkweed reaching 0.8 m (2 ft 7 in) tall by 0.4 m (1 ft 4 in) wide, growing at a fast rate. Hardy to UK zone 8 and not frost tender. Flowers bloom June to August, pollinated by bees, insects, moths, and butterflies. Noted for wildlife attraction. Grows in light sandy to medium loamy soils with good drainage and poor soil tolerance. Tolerates mildly acid to basic pH. Requires full sun. Prefers dry to moist conditions and tolerates drought. Ranges from California and Nevada north to Washington and Idaho and south into Baja Peninsula.

Edible Uses

Young blossoms - cooked. Some caution is advised, see the notes on toxicity at the top of the page. Mexican milkweed (Asclepias fascicularis), a perennial of the dogbane family (Apocynaceae), grows from California and Nevada north to Washington and Idaho and south into the Baja Peninsula. Like other milkweeds, it contains toxic cardenolides in its milky sap, which can cause serious health effects if eaten raw, and must always be approached with great caution. The leaves and flowers were cooked and eaten as vegetables by Native American groups in California, but no other parts of this species are reported as food. It is important to note that milkweeds remain poisonous when dried and are especially dangerous to livestock; as little as half a pound of fresh leaves can be lethal to a 100-pound sheep. Although cooking can neutralize toxins in edible species, raw consumption is unsafe, and foragers must be extremely careful with this genus. Mexican milkweed typically blooms from June to August, providing a limited seasonal opportunity for harvest.

Traditional Uses

The young flowers are eaten cooked.

This uses section is brief — help expand it

Medicinal Uses

None known

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.

Distribution

It is a subtropical plant.

Where It Grows

North America, USA,

Cultivation

Asclepias fascicularis is a plant mainly in Mediterranean climates with hot summers and cool or even cold winters, with most precipitation falling in the cooler months. Outside of this climate, the plant will require well-drained soil and hot summers, with some protection in cold winters, if it is to thrive. This protection can often be applied as a mulch, though it would need to be removed before new growth begins in the spring; otherwise, slug damage is very likely to occur. Prefers well-drained light, rich, or peaty soil in a sunny position. Succeeds in poor soils. 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 well-established plants are 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.

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.. 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 Uses

Rubber can be made from latex contained in the leaves and the stems. Special Uses

Notes

There are 100 Asclepias species.

Synonyms

Also Known As

Mexican milkweed, Asclepias fascicularis

References (3)

• Beckstrom-Sternberg, Stephen M., and James A. Duke. "The Foodplant Database." http://probe.nalusda.gov:8300/cgi-bin/browse/foodplantdb.(ACEDB version 4.0 - data version July 1994) (As Asclepias mexicana)
• Icon. 1(2):42, t. 58. 1791 (As Asclepias mexicana)
• World Checklist of Useful Plant Species 2020. Royal Botanic Gardens, Kew

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