Giant sensitive plant, also known as Botswana wonder and sensitive water plant, is a floating perennial forb that belongs to the pea family, Fabaceae. The genus Aeschynomene contains largely aquatic species, collectively known as the joint-vetches.
The name “joint vetch” arose because when touched, the leaves in plants of this genus curl up slightly to moderately. This is also why Aeschynomene fluitans is called the giant sensitive plant, after its large leaves that fold inward a bit when touched. These return to normal after a few minutes of being undisturbed.
This plant is actually only considered native to southern Africa, including the countries Angola, Botswana, Democratic Republic of the Congo, Namibia, Tanzania, and Zambia. It can be grown in just about any place that is temperature or subtropical in standing water, but is considered invasive outside of its native countries. It makes a pretty (and useful) pond plant, but be aware of its invasiveness when planting.
Facts, Benefits & Uses of Giant Sensitive Plant
As with many species in the Aeschynomene genus, Botswana wonder is excellent at filtering water and helping to control algae populations. While able to fix nitrogen in the water, they’re not as good at this as others in the joint-vetch genus.
This is because of their aquatic nature – Aeshcynomenes that are able to grow in at least some soil can form root nodules when in the presence of Bradyrhizobium bacteria (as well as several other bacteria strains). These bacteria forge a symbiotic relationship with the plant, encouraging the development of these nodules to aid in greater in more efficient nitrogen fixation.
With bright yellow flowers that bloom from early summer through early autumn, A. fluitans is also a good plant for pollinators. Butterflies, bees, flies, moths, and some birds are drawn to the vibrant blooms.
Giant Sensitive Plant Growth, Hardiness & Climate
Giant sensitive is quite aptly named – as an aquatic plant lacking woody stems, its height is more so limited to around 10 inches or less. However, each plant can spread as much as 8 feet if conditions are right, though closer to a foot per plant is more common.
If planted along an edge, such as a waterfall, the plant will happily cascade over the edge via trailing vines like those of a garden pea plant. It is usually the plants that are placed along overhangs that are able to spread several feet. If you live in an area with winter, the plants will die back and of course not grow as much as they would in a temperate location that won’t limit their growth season.
These plants do best in hardiness zones 9 and above, but as low as 7 work well provided you’re alright with them dying back in the winter or bringing them indoors. Blooming usually begins in May and extends all through summer, sometimes longer depending on your location. Both full sun and partial shade are perfectly fine with this plant.
How to Plant Giant Sensitive Plant In Ponds
If you’re not growing from seed, all you need to do is place your giant sensitive plant directly in the water. You can allow it to float freely, or place it between rocks or in an aquatic basket to keep it from moving around. Anywhere in your pond works well, whether the water is deep or shallow. To fully enjoy this plant, consider placing it in a hanging water container or by rocks or a waterfall where it can cascade over any edges.
Giant sensitive plant can be propagated simply and easily from cuttings. These cuttings can then be placed directly in the pond. You may also place the cuttings in some soil to anchor them in place, so long as the soil is in water. Seeds can be pressed gently in moist soil, and transplanted to water after germination occurs. They can also be planted directly along the saturated banks of your pond, where they’ll likely germinate without much effort on your part.
How to Care For Giant Sensitive Plant
If Botswana wonder is growing larger than you’d prefer, simply trim the leaves and branches (at the nodes, as this will minimize stress to the plant) as needed. You should also trim any dead or dying leaves, cleaning them out of your pond after to encourage healthy water quality. Be sure to also remove any dead or dropped flowers from the water. Fertilization isn’t necessary, as the plant should be able to get everything it needs from the water.
A note when disposing of any cuttings: do not simply toss them to the side! These cuttings can easily establish themselves in lakes, streams and the like and have been known to completely overtake native vegetation. Dispose of any cuttings either in the trash, or in a covered compost bin.
How to Winter Giant Sensitive Plant
As a plant that hails from southern Africa, you can probably imagine that giant sensitive plant doesn’t much care for frost or snow. In the northern US and Europe, you’ll need to either transfer Botswana wonder indoors for the winter, allow it to go to seed and possibly re-sprout the following spring, or just purchase a new one each year.
Is Giant Sensitive Plant Toxic, Poisonous or Invasive?
Giant sensitive plant is considered to be quite invasive outside of its native range in southern Africa. This plant is listed as invasive in most US states, but is still, so far, legal to own in most states (be sure to double check regulations for your state if you reside in the US). While little literature can be found regarding its legality in the UK, Australia, and just about anywhere else in the world, any species that is no longer in its native range is inherently non-native in the new area and has the potential to damage ecosystems greatly.
If you live in the US, seek out shyleaf (Aeschynomene americana), which is much the same as Botswana wonder but, most importantly, native to the Americas, and slightly smaller with pink flowers. Aeschynomene indica is native throughout much of Asia and Africa, and is semi-aquatic (able to grow in soil as well as water), with a smaller and more delicate appearance than that of giant sensitive plant. Both of these species can be found in Europe and, while not native, they have not yet overtaken areas and are as such considered to be “naturalized.”
Due to Botswana wonder’s fast growth and vast spreading potential, it’s very easy for it to become an invasive species. Be a responsible gardener and ponder and do take care to keep this plant contained in your pond, either via cutting regularly or growing it in containers. As mentioned above, properly dispose of any cuttings in the trash or a covered compost bin where they won’t be able to establish in natural waterways.
Nothing could be found regarding the documented toxicity for this species, so it is likely safe for fish and wildlife. Nevertheless, clean any clipped or dropped foliage from the water to maintain healthy water quality and happy fish.
Is Giant Sensitive Plant Edible? Will Fish Eat it?
As a member of the legume/pea family, the leaves, stems, and seeds of the giant sensitive plant are edible. Historically, they’ve been consumed as a vegetable in the plant’s native countries. It’s also been used dried as fodder for cattle and sheep. More adventurous fish may try nibbling on the plant, though Botswana wonder is generally left alone by most fish.
Where to Buy Giant Sensitive Plant & Seeds? (UK & US)
Botswana wonder is most easily obtained from online retail outlets. Some nurseries and garden centers may be able to special order it in if needed.
