Ipomoea purpurea

Today we have an entry written by Taisha prior to her departure. Taisha wrote:

Ipomoea purpurea, or the common morning glory, is photographed here by Hugh Nourse (aka Hugh and Carol Nourse@Flickr). This photo was taken last month along the Blue Ridge Parkway in North Carolina. Many thanks for sharing, Hugh!

The bindweed or morning-glory family consists of over 1600 species, including Ipomoea purpurea. This species is an annual vine native to Mexico and Central America, but it has established elsewhere (e.g., in much of the USA and parts of Canada). This species is cultivated worldwide as an ornamental due to its large and showy trumpet-shaped flowers. The Mexican populations are monomorphic for flower colour (having only purple flowers), whereas the introduced populations in the USA are highly polymorphic for flower colour, ranging from white to pink to red and purple. Common morning glory possesses a number of weedy traits such as rapid and aggressive growth, high seed output, and extended seed dormancy in soil seed banks. Indeed, this opportunistic colonizer of disturbed sites is now regarded as a noxious weed in the southeastern United States.

Little is known about the timing and geographic origin of US populations. One hypothesis is that this species was introduced into the United States with maize cultivation ~4000 years ago and subsequently dispersed (called the “Maize migration hypothesis”). Another hypothesis is that it was introduced through Europe after European contact with the New World (termed the “European migration hypothesis”). In this scenario, Spanish explorers are suspected of collecting seeds of Ipomoea purpurea in its native range, sending them to Europe to plant in monastery gardens, and then later being introduced to colonial North America (north of Mexico) around 1700.

In a study by Fang et al., the researchers examined data from 11 loci and 30 Ipomoea purpurea accessions from the native range of the species in Central and Southern Mexico, and 8 accessions from the southeastern USA in an attempt to infer the precise Mexican origins of the southeastern USA populations.

Fang et al. assert that Ipomoea purpurea made its way to southeastern USA via Europe. They support the European migration hypothesis due to the low genetic diversity of the southeastern USA population compared to Mexican populations. This suggests a strong founder effect consistent with multiple founder events (e.g. Mexico to Europe and Europe to southeast USA). This is paired with a severe population bottleneck, which contrasts with the maize diversity in the USA. If common morning glory did migrate with maize after all, one would expect a larger diversity, given the shared demographic history of morning glory and maize. Fang et al. attribute the higher levels of flower colour polymorphisms in the southeastern USA compared to native Mexican populations to the desire for diverse flower colour, consistent with the introduction of this species from Europe to the USA for its horticultural appeal.

As for the origins of the southeastern USA populations, the researchers suggest the western Mexican populations (rather than the southern or eastern). They propose this origin based on their genetic assignment analysis, haplotype composition, and the degree of shared polymorphism. They note that the eastern Mexican populations likely did contribute genetically, but the western populations contribute in large part for three reasons. First, the western Mexican population has the highest diversity and thus a larger effective population size. Secondly, based on the European migration hypothesis, the early trade routes from Mexico to Spain were from the Valley of Mexico eastwards through Xalapa and onto the port of Veracruz. Lastly, they point out that the domestication of maize was ~9000 years ago in the Balsas River Valley, which is ~300km southwest of the Western population. If this were the case, then one would assume the colour variants of Ipomoea purpurea would have spread through Mexico and Central America along with maize culture, rather than the monomorphic purple form.

The researchers end by noting that although it is likely that Ipomoea purpurea first migrated to Europe before being introduced to the southeastern USA, there was substantial trade in the Aztec and earlier eras between the Valley of Mexico and regions to the east and south of Mexico, allowing for seed to be traded before the arrival of Europeans. Also, they mention that the accessions from the Valley of Mexico that show high similarity to the southeastern USA populations could have accompanied modern travelers or been reintroduced back to Mexico to be planted in gardens with likely escapes (see: Fang, Z. et al. (2013). Tracing the geographic origins of weedy Ipomoea purpurea in the Southeastern United States. Journal of Heredity. doi: 10.1093/jhred/est046).

Ipomoea purpurea

15 responses to “Ipomoea purpurea”

  1. john voss

    thank you Taisha for a great read! I will be rereading it several times. Science at it’s best.

  2. Bugscuttle

    I love it, whether as Bindweed, the glorious ‘Flying Saucer’, the picture featured as well. It’s common, but tenacious and beautiful.
    Of course, speaking as a gardener, Bindweed is the devil incarnate!
    Thanks for a good read as well as a good pic!

  3. Richard Old

    Based on the large bracts subtending the flowers, I think it is unlikely that this is Ipomoea purpurea but is possibly one of the more colorful forms of Calystegia sepium.

  4. Pat

    I am pretty sure that is Calystegia pulchra, Hairy Bindweed. There is some just down the road from me. Terrible weed but spectacularly beautiful, as its specific name suggests. It was cultivated as an ornamental in the early 19th century in the UK but escaped. Very similar to C. sepium but the pink loveliness gives it away.

  5. Steve Edler

    Morning Glory seeds achieved a brief popularity many years ago as an hallucinogenic drug (not by me I hasten to add).

  6. Betty Cunnin

    Having grown I. purpurea occasionally for seasonal colour, I too thought the flower was more characteristic of Calystegia, but I see pulchra is not an accepted species name. Perhaps C. sepium as suggested by Richard Old; maybe subsp. spectabilis? http://www.theplantlist.org/tpl1.1/record/tro-8502815
    Does anybody know the determinable differences (as seen in the field) between these genera?

  7. Pat

    How about Calystegia sepium ssp appalachiana?
    Here is a key to the Bindweeds of Alabama and adjacent states. Not having a scale makes it tricky, though.

  8. Hugh Nourse

    In other photos of the same plant the bracts are clearly those of Ipomoea purpurea. They narrow and reduce to a sharp point.

  9. Pat

    Thanks, Hugh, but you don’t have those other photographs on your Flickr stream, do you?
    If you look at the key I linked to in my last comment you will see a photograph of an identical flower to this from the Blue Ridge Parkway identified as Calystegia sepium ssp appalachiana.
    I would suggest that you saw Ipomoea flowers that were not on the same plant.

  10. Hugh Nourse

    I have posted another angle of the same two flowers showing their bracts. They are not hairy, and they have the shape the Weakly uses as key to the Ipomoea purpurea.

  11. Pat

    I did not know this Weakley. Having downloaded it I see the problem is that it only has keys with no proper description or photographs of the plant for you to check if you have chosen the right path. As they write in the introduction:
    It is easy to make the dangerous assumption that “it keys to it, so it must be it”. … … it is important that you compare your “answer” from keying to the description and drawings in the Flora of Virginia, to written technical descriptions and drawings in other floras (increasingly available online, such as the Flora of North America), to specimens in area herbaria, and to photographic images available in other books and online.
    A photo from Bolivia on Tropicos, http://www.tropicos.org/Image/100179897
    This description of Ipomoea purpurea is from the Flora Zambesiaca, a little far away again, but you can see that it cannot be the plant in your photo:
    peduncle up to 15 cm. long; pedicels shortly hairy or with a few bristles, 8–15 mm. long; Sepals unequal, 10–15 mm. long, accrescent up to 20 mm. long in fruit; outer ones oblong, acute with bristly patent hairs in basal portion; inner ones with narrow scarious margins, linear-oblong to linear, acute with a few bristles near the base.
    I reiterate that the paper I linked before is quite definitive.

  12. Hugh Nourse

    Okay. I concede. After reviewing the Weakley key, I believe it is Calystegia sepium ssp. appalachiana. Still the article about Ipomoea purpurea was most interesting. Weakley is the standard reference for flora identification in the southeast. I was also using the Tennessee Wildflower Guide from the Tennessee Native Plant Society. What initially threw me off was the pink variegation in the flower. Calystegia is supposed to be solid pink.

  13. Ian Sturges

    A little off topic considering the previous comments, but, would anyone know the song about the Morning Glory and the Honeysuckle falling in love? Funny piece by two British comedians, but that’s all i have got. any help would be appreciated. 🙂

  14. Pat

    That song would be “Misalliance” by Flanders and Swann.

  15. Ian Sturges

    Thanks for that, Pat. Now, I will sleep easier. 🙂

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