Asclepias asperula

Taisha is again the author:

Today’s photographs (image 1 | image 2) are of Asclepias asperula. The first image is that of a scanned slide uploaded to the Botany Photo of the Day Flickr Pool by Michael Huft@Flickr. Michael photographed this milkweed in Woodward County, Oklahoma back in 1980! The second photograph (also uploaded via the Flickr pool) is courtesy of sonnia hill@Flickr, taken in Texas’s Ellis County in April 2003. Thanks Michael and sonnia!

Asclepias asperula is a member of the Apocynaceae or dogbane family. This family is distributed over much of the world, excluding only Antarctica and the northern North Hemisphere. This species, though, is only found in a narrow part of the entire family’s distribution. It occurs in northern Mexico and central & southwest USA, where it is typically found in sandy soils along roadsides, pastures and open hillsides. Asclepias asperula has many common names including antelope-horns, green-flowered milkweed, spider milkweed, and spider antelope-horns.

A perennial clump-forming species, Asclepias asperula has a densely hairy stem and narrow leaves that are slightly folded lengthwise. In the summer, umbels of greenish-yellow flowers appear. Later, large follicles are produced. These curve to resemble an antelope horn, hence one of its common names. Seeds are arranged spirally around a central axis within the fruit. Long white hairs are attached to the seeds, aiding in wind-dispersal when the follicle dehisces.

Monarch butterfly (Danaus plexippus) larvae are obligate herbivores requiring members of the Apocynaceae to feed upon. Typically, these are members of the genus Asclepias, as mentioned in earlier posts on Botany Photo of the Day: Asclepias tuberosa and Liatris ligulistylis.

As many readers are likely aware, the monarch butterfly is in decline. In a survey conducted by the WWF-Tecel Alliance and CONAP, the percentage of Mexican forest occupied by monarch butterflies is used as an indicator of the number of butterflies that reach the country for hibernation. This year the numbers are at the lowest level in the past 20 years. The decrease in the butterfly population size is attributed to several factors, including a decrease in milkweed. There is an international effort to conserve monarch populations, with one method being to conserve and restore milkweed species in suitable habitats within their native range (see: Luna, T., and Dumroese, RK. 2013. Monarchs (Danaus plexippus) and milkweeds (Asclepias species): The current situation and methods for propagating milkweeds. Native Plants Journal. 14(1):5-15).

Asclepias asperula
Asclepias asperula

15 responses to “Asclepias asperula”

  1. steve

    Ahh yes! This milkweed grows abundantly here in the Austin, Texas area too particularly when the monarchs fly past!

  2. Peony Fan

    Fantastic photos! Thank you. The whole milkweed family is both beautiful and fascinating.

  3. michael aman

    Loss of milkweeds does not seem to be a problem on the East Coast and in the Northeast. Isn’t it mostly a problem where GMO corn is grown, fence to fence, with no buffer zones, and use of glyphosate in abundance? (I won’t use the brand name). Come on, Big Corn Conglomerates, give the monarchs a break!

  4. Dennis Nyberg

    Gee, people discover where the monarchs roost in winter and after a short delay the decline begins. If it continues it should be attributed to National Geographic and over organizations that ‘promote’ nature thru images.

  5. Floater

    Any comment about the pollinator? I notice its pattern to be similar to that of the milkweed bug.

  6. marlene

    This is just a masterpiece of nature. Thanks for the wonderful photo.

  7. Elizabeth

    Just love the Milkweed in Fall, when the seed pods burst out fluffy magnificence!!!

  8. chris jankot

    I don’t believe that education promotes abuse! (previous comment). I do believe that i do my part byletting all the milkweed that sprouts on my property grow,regardless of where it shows up. It’s bloom is wonderfully scented. When we find a monarch caterpillar, we bring it in andfeed it until it emerges fromit’s cocoon,to protect it. It’s easy to do. Then it’s back tomother nature,good bye little mirale!

  9. Fred Bess

    Interesting images. Members of this family are among my favorites, but a question: When was Asclepias moved from asclepiadaceae to apocyanaceae, or were they simply merged?

  10. Linda R

    I think the insect in the first picture looks like a robber fly.

  11. Fritz

    This milkweed grows in the rocky clay soils in the foothills above Salt Lake City, mostly on south facing slopes. It’s incredibly beautiful and one of my favorite plants!

  12. Bart Wursten

    What a wonderful post today. I am a great fan of the entire Apocynaceae family and Ascleps in particular. To Fred Bess: APG II, about 10 years ago list Asclepiadaceae as part of Apocynaceae. This merge is based on the relationships established by phylogenetic research. The former Asclepiadaceae now forms the subfamily Asclepiadoideae, with the exception of Secamone and a few closely related genera. These now form a separate subfamily within Apocynaceae called Secamonoideae. The former Periplocaceae also form a separate subfamily, Periplocoideae.

  13. Daniel Mosquin

    Insect looks like a bumblebee to me…
    As to Dennis’s comment: there are no doubt instances where organisms are loved/touristed to death, but that wasn’t my impression with the monarchs (having seen them a few years ago in Mexico).
    First, access to see the monarchs is restricted in a couple ways — in the monarch reserve we visited, you could not walk into the core of where the butterflies were residing and disturb them. In at least that instance, it wasn’t a free-for-all. A second sort of restriction is that the reserve we visited required a bit more local knowledge with regard to personal safety, being in one of the states that is warned about by the US Department of State: “You should defer non-essential travel to the state of Michoacán except the cities of Morelia and Lázaro Cardenas where you should exercise caution.”
    I vaguely recall there is a reserve close to Mexico City where the number of butterflies was fewer but access was easier than the one we visited.
    There was also a bit of triage if memory serves — the choice was either help the local people develop a sustainable economy through setting aside reserves and enabling tourism, or, deforest. Presently, the local people are invested in ensuring the monarchs survive when at their winter colonies in Mexico (hence some of the access restrictions).
    Maybe that’s all changed in the 4 years since I visited, but the causes of the collapse identified by WWF and partner organizations seems a more likely scenario to me.

  14. Jessica

    That is an especially beautiful milkweed. Thanks so much for featuring it.
    Here, in New York City, there is an initiative to encourage the planting of native milkweeds and other pollinator-friendly plants in home gardens and community gardens. More and more of our parks and botanical gardens are focusing on improving their plantings with an eye to encouraging pollinators, birds and other wildlife….it’s about time!
    Do you know if the Asclepias asperula is hardy in Zone 7, or if it’s available commercially? It’d be a highlight in any garden.
    Thanks for a great plant photo and a reminder about how important milkweeds are to the Monarch population.

  15. Art Jones

    Just wanted to say how much I enjoy your photos from UBC and their enhancement by Taisha’s elegant commentaries, which as well as being fascinating, do something to revive my rusty botany. They are a great advertisement for UBC, Vancouver and Canada.

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