Unfortunately, pōhuehue's large colorful funnel-shaped flowers only last a day. However, most wild and cultivated plants bloom continuously year round. Fruits are dry capsules, each typically containing four fuzzy seeds (Photograph courtesy of 葉子 leaf0605 Public Domain.). Pōhuehue stems can extend for dozens of feet, making it sometimes difficult to tell where one plant ends and another begins; these long and sometimes parallel stems are the origin of its common name, railroad vine. Rarely, pōhuehue stems become fasciated (an abnormal type of fused growth resulting in a flattened ribbon-like structure). Pōhuehue works great as a groundcover, particularly in coastal areas where it's less prone to attack by its many pests, or as a living shadespace; note that because pōhuehue is not a climbing vine with tendrils, the above plant likely needed a bit of help climbing up to the top of this trellis where it was then able to spread atop the roof's lattice. (Photographs of wild field of pōhuehue flowers, fasciated stem, cultivated seaside groundcover, and trellis pōhuehue all courtesy of Forest & Kim Starr CC BY 4.0.)

Growth Requirements

General

    Perhaps the best testament I (Koebele) can give to the resilience of pōhuehue is that we still see wild plants in nearly all of our beach parks here on O‘ahu where almost a million people live (and where millions of tourists visit each year). Just imagine if we actively planted pōhuehue at our beach parks (similar to Honolulu City & County's efforts to plant naupaka kahakai and nui) — we would have a lei of pōhuehue ringing our island home. 

    Pōhuehue is a great groundcover for coastal areas. Use it to discourage access to dangerous shorelines (see photograph above) or just add a touch of green to a barren beach. Pōhuehue, along with other native plants like ‘aki‘aki (Sporobolus virginicus) and ‘ākulikui (Sesuvium portulacastrum), can help stabilize beaches and dunes by reducing erosion. Inland, pōhuehue is probably best used as an accent in a garden or container, where it can more easily be protected from (and treated for) its, unfortunately, numerous pests and diseases (see below). 

    Pōhuehue thrives in sites with full sunlight for all or most of the day, and will languish and become a target for pests in constantly shaded locations. This native vine also evades many of its pests and diseases when planted in a dry, windy place. 

    Even in the driest locations, new pōhuehue plants only require a few weeks of watering to establish themselves. After that, avoid regular watering and only water your plant if you actually see it wilting (but be sure to first look for an alternative cause, the sweetpotato weevil) or if you want to accelerate your plant's growth beyond normal. Obviously, containerized pōhuehue require regular watering.

    Well-drained soil or media is a must when growing pōhuehue, and while it can grow in just about any type of soil, it does best in sandy sites. Pōhuehue is tolerant of drought, intense heat, and extreme salt spray (which almost certainly deters many of its pests and diseases). And, while pōhuehue's stems and leaves can be killed by long exposure to seawater (such as during an extra-high tide or storm), its fleshly taproot often survives to later regrow these lost organs.  

    Store-bought pōhuehue are typically (and easily) grown from cuttings. Therefore, your plant should begin flowering soon after you plant it. In its optimum environment (described above), pōhuehue grows quickly and can rapidly cover an open space. To restrict your plant to a given area and to encourage branching, periodically prune its extra-long stems; these can be used to produce new plants. While not required, pōhuehue seems to grow faster and stay greener if periodically fertilized. Apply a balanced controlled-release fertilizer with minor elements every six months, or use an organic or inorganic water-soluble fertilizer diluted to ⅓ to ½ the recommended strength every few months. Do not overfertilize since this will make your plants more attractive to pests.

Pests and Diseases

    Pōhuehue is attacked by a wide variety of pests and diseases. These pests and diseases are less common and their damage less severe for plants growing in sunny dry sites near the ocean. In contrast, pōhuehue planted inland or in a site with suboptimal conditions (i.e., low light, too much rain) are more consistently plagued by the pests listed below.

Sweetpotato weevil (Cylas formicarius): Weevil larvae will tunnel through the stems of pōhuehue to reach its large swollen tuber (i.e., taproot) where they feed en masse. Therefore, the infestation is often not noticed until some of the plant's vines begin to wilt or turn yellow. If you see wilting or yellowing, you should dissect the wilted stem to look for tunnels, or dig up one of your plants to find the weevils or their tunnels in the tuberous taproot. While there are some new studies exploring the use of biological controls, using a systemic insecticide is probably the best current treatment for infested plants; since humans typically don't eat pōhuehue, this treatment doesn't have the dangers associated with using a systemic pesticide on infested sweet potatoes. For more information about the sweetpotato weevil, check out Capinera [2014].

Sweetpotato hornworm or Pink-spotted hawkmoth (Agrius cingulata): We have never seen this insect on pōhuehue; however, others have. The larvae are more common on sweet potato (Ipomoea batatas), where they consume the leaves. If you see a hornworm caterpillar on your pōhuehue, the easiest thing to do is remove it by hand. If the infestation is severe or widespread, consider spraying with organic pesticides like neem, pyrethrum, spinosad, or Bt. For more information about Agrius cingulata, check out LucidCentral. 

Sweet potato bug (Physomerus grossipes): We have infrequently seen this bug or its eggs on pōhuehue. It seems to cause little damage (sucking the sap from the plant) and is easily removed by hand.

Flea beetles: This pest typically causes only minor to intermediate damage to the plant's leaves. See a photograph of flea beetle damage on the Pests & Diseases webpage, as well as ways to deal with this pest. 

Spider mites: We have only seen this pest on pōhuehue growing in windless dry locations. See Pests & Diseases for ways to combat spider mites.

Mealybugs and scale insects: In our experience, these two insect pests are rare on pōhuehue. And, when we do see them, they are almost always being farmed and protected by ants. See Pests & Diseases for ways to deal with these three pests.

Snails and slugs: These herbivores are most commonly seen in dense and/or wet (because of rain or watering) plantings of pōhuehue, where they can cause significant damage, sometimes consuming entire leaves or stem tips in a single night. See Pests & Diseases for ways to combat snails and slugs.

Cercospora leaf spot: This disease is typically caused by one of two species of parasitic fungi in the genus Cercospora. Infections can become extensive and severe on dense plantings, as well as on weakened plants in suboptimal settings. Infections often begin during the wetter months and are more likely at sites with excessive irrigation or poorly draining soil, or those that have little sunlight or airflow. The infection typically starts from the older parts of the plant and progresses toward its newest growth. The leaf spots are usually circular, often surrounded by a red to purple border. In older lesions, necrotic (dead) areas typically develop in the center of the lesion. Cercospora infections can cause severe defoliation and massive stem dieback. Unfortunately, from our online research, there doesn't seem to be an effective chemical treatment to control Cercospora leaf spot. Disease management recommendations include: improving sanitation, increasing air movement, avoiding or reducing overhead irrigation, keeping plants well fertilized, avoiding large or dense plantings, and growing plants in full sunlight. In the past, whenever we've seen afflicted pōhuehue, we have simply and promptly removed the infected leaves or stems and tried to improve growing conditions (e.g., increased light, decreased watering, reduce foliage density, fertilize). For more information on Cercospora leaf spot, check out this online article by Scot Nelson [2013].

White rust: This disease is caused by Albugo ipomoeae-panduratae, an oomycete similar to Pythium, Phytophthora, and downy mildew pathogens. It can cause severe damage, especially to dense plantings, attacking all above-ground parts of the plant and resulting in defoliation, reduced flowering, and stem dieback. Recommended fungicides for control include those with the active ingredient azoxystrobin, cyazofamid, mefenoxam, or pyraclostrobin [Brown & Frank 2020]. We have never seen this disease on our pōhuehue and, therefore, cannot provide any additional advice on treatment(s).

Kaunaʻoa (Cuscuta sandwichiana): Kaunaʻoa is an endemic Hawaiian parasitic plant commonly seen on wild pōhuehue. Therefore, in contrast to our advice for the above-described pests, we recommend you keep rather than try to get rid of any kaunaʻoa growing on your pōhuehue. Normally, the damage it causes to pōhuehue is minimal; however, if you think things are getting out of control, kaunaʻoa is easily removed by hand (to make a lei?)  In Na Mo'olelo Hawai'i o Ka Wa Kahiko: Stories of Old Hawaiʻi by Roy Alameida [1997], there is an interesting love story about kaunaʻoa and pōhuehue.

Photographs below show: Sweetpotato weevil (Cylas formicarius) courtesy of Graham Wise CC BY 2.0. Larva of Sweetpotato hornworm (Agrius cingulata) on sweet potato (Ipomoea batatas) courtesy of Forest and Kim Starr CC BY 3.0 US. Sweet potato bug (Physomerus grossipes) with eggs on sweet potato (I. batatas) courtesy of Damien Wallace CC BY 4.0. Cercospora leaf spot on pōhuehue courtesy of Forest & Kim Starr CC BY 2.0. White rust (Albugo ipomoeae-panduratae) on pōhuehue courtesy of Forest & Kim Starr CC BY 2.0. Kaunaʻoa (Cuscuta sandwichiana) on pōhuehue courtesy of Scot Nelson Public Domain.

Special Features and Information

General

   There are more than 1,650 species within about 60 genera in the Morning glory family (Convolvulaceae), distributed worldwide [WikipediA;Convolvulaceae]. Pōhuehue is related to some locally popular food plants such as ʻuala or sweet potato (Ipomoea batatas) and ung-choi or swamp cabbage (I. aquatica).

    In addition to Ipomoea pes-caprae, native Hawaiian members of Convolvulaceae include: the endemic and endangered Bonamia menziesii; the indigenous makihi (Cressa truxillensis); the endemic and parasitic kaunaʻoa (Cuscuta sandwichiana); the indigenous hunakai (I. imperati), koali ʻawa (I. indica), and White-flowered beach morning glory (I. littoralis); the endemic Hawaiian moon flower (I. tuboides); and the endemic pāʻu-o-hiʻiaka (Jacquemontia sandwicensis) [Flora of the Hawaiian Islands].

    Pōhuehue is often a host to its parasitic relative kaunaʻoa (Cuscuta sandwichiana). In Na Mo'olelo Hawai'i o Ka Wa Kahiko: Stories of Old Hawaiʻi by Roy Alameida [1997] there is an interesting love story about how this association came to be.

Hawaiian Name

    In addition to being the Hawaiian name for this species, pōhuehue has three other meanings: (1) the poetic name for a fisherwoman's skirt, so named because the goddess Haumea would drape pōhuehue about herself as she fished; (2) a variety of yellow sweet potato; and (3) a type of stone used to polish canoes [Pukui & Elbert 1986].

Etymology

    Ipomoea is derived from the Greek words, ips, for "worm," and homoios, meaning "similar to," a reference to the species' twining habit [Wagner et al. 1990]. The hyphenated species name, pes-caprae, is from the Latin words, pes, meaning "foot," and caprae, meaning "she-goat," together translated as "the foot of a she-goat," referring to the shape of the species' leaves being similar to that of a she-goat's foot [Latdict]. The subspecies name, brasiliensis, is a Latinized reference to the country of Brazil (Brasil), which is part of the species' pantropical range [Gledhill 2008].