CA Native Spotlight: Asclepias

May 15, 2020

Summer can be one of the most beautiful yet most brutal seasons for our cultivated landscapes. As we seek shade, solace, and salvation from the beating sun, our local wildlife does the same. We can do our part to provide habitat through careful selection of summer-loving landscape plants. Lucky for us, many choice landscape plants for heat and drought tolerant conditions also fall under the category of California Native species.

The first and one of the most effective summer blooming native plants to keep in your yard would be the humble Milkweed, Asclepias. Though the common name for this plant includes “weed” these perennials are anything but that. The botanical name of this species – Asclepias – is derived from the Greek god of medicine Asklepios but do not let this plant’s ties to the ancient god of medicine fool you. All parts of this milkweed can be poisonous if consumed due to a milky white sap that seeps from damaged leaves and stems which is the inspiration for this plant’s colloquial name, Milkweed. 

– Monarch Butterfly and Sphynx Moth pollinating Asclepias speciosa (USFWS Mountain-Prairie / Public domain)-

 

Native to most of North America, Milkweed is a widely popular choice because of the support it provides to one of California’s most recognizable species – the Monarch Butterfly. It’s quite remarkable how these species have coevolved; the Monarch depends on Milkweed as a vital part of their life cycle as it provides habitat and nutrition, and this relationship is absolutely not mutual. While Monarch caterpillars do their best to consume plant material to grow, Milkweed does its best to poison the young caterpillars; this however has not lessened the butterfly’s dependency on Asclepias. Female Monarchs utilize Milkweed as a safe place to lay their eggs, on leaves that protect and will eventually feed growing caterpillars. Monarchs as a population, along with countless pollinator species have experienced a decline in recent years. As active members of our environment, we can do our part to incorporate some ecologically supportive, yet still attractive plants into our landscapes.

Here at the nursery, we carry a wide variety of members of the Asclepias family, today we’re just going to focus on two: Asclepias speciosa (Showy Milkweed), and Asclepias fascicularis (Narrowleaf Milkweed).

Both of these herbaceous perennials are similar in form and habit, where they differ is in foliage and flower color display. Showy Milkweed presents broad medium green leaves that can be up to 5 inches long, arranged in opposite pairs along upright stems. During spring and summer months, these upright stems are topped with large umbels of intricate, pale purplish-pink star-shaped flowers that have peculiar, reflexed calyxes. 

-Flowers of Asclepias speciosa, Showy Milkweed (USFWS Mountain-Prairie / Public domain)-

 

Asclepias speciosa (USDA NRCS Montana / Public domain)-

 

Narrowleaf Milkweed appears as its name hints – with narrow medium green leaves that can grow up to 5 inches in length, bundled in fascicles (The word fascicles comes from the Latin word for bundles – as the foliage appears to be bunched in clusters along upright stems.). Umbels of rosy pink, flowers emerge in 2 inch clusters throughout spring and summer months.

-Flowers of Asclepias fascicularis (Björn S… / CC BY-SA)-

 

-Flowers and foliage of Asclepias fascicularis (Eric Hunt / CC BY-SA)

 

Growing quickly to 2 – 3 feet high and about 1 foot wide and tolerant of poor soil and drought conditions, Milkweeds will easily naturalize in hard-to-grow spots in the garden through rhizomes and seed propagation. Both Showy and Narrowleaf Milkweed will experience winter dormancy, where they will die back as the weather shifts to cooler temperatures and regenerate the following spring.  These plants are very showy when in bloom, and irresistible to insects and people alike. Presence of Milkweed in the garden will attract not only butterflies, but hummingbirds and many other insect species including golden aphids, red milkweed beetles, blue milkweed beetles, large milkweed bugs, and tarantula hawk wasps – although the presence of these insects has very little to no ability to damage your milkweed plants. There are no serious pests or diseases that impact Milkweeds. Devil Mountain offers both Showy Milkweed and Narrowleaf Milkweed in 4” and 1 gallon containers.

 

Sources:
“Asclepias speciosa.” Missouri Botanical Garden. https://bit.ly/2WyTcOp.
Bornstein, Carol, David Fross, and Bart O’Brien. California Native Plants for the Garden. Los Olivos, CA: Cachuma Press, 2014.
Monarch Joint Venture. https://monarchjointventure.org/.
Norris Brenzel, Kathleen, ed. The New Sunset Western Garden Book. 9th ed. New York: Time Home Entertainment, 2012.
San Marcos Growers. https://smgrowers.com/.