Sesbania (Riverhemps)

In August, 2018, while visiting my parents in Nederland, Texas, I saw a really interesting looking plant growing in a ditch. It was at least 6-7 feet tall, with yellow flowers hanging in bunches. After driving by it several times, I talked my husband into stopping on the shoulder so I could jump out and take a quick picture. It came up on iNaturalist as “Rattlebush” (Sesbania drummondii.) It's a plant in the legume family, and has the pinnately compound leaves typical of these plants, but it's as big as a small tree. It clearly wasn't planted, so I wondered where such an odd plant had come from. On our drive to Houston a few days later, we saw these plants everywhere! I grew up in Southeast Texas, but I had never seen (noticed?) one of these before in my life! I had observed a Big Pod Sesbania in DFW area, and I soon realized these two were related. When I got back home, I found several more of both types of Sesbania. Next, I found a similar looking plant that turned out to be Bladderpod, Sesbania vesicaria, and soon I saw several more of those. Once these plants developed seed pods, I really loved them! Each had a totally distinct kind of seed pods - that's the kind of plant I like! You can definitely tell them apart, even in pictures! There are also several other species in the Sesbania genus, but those don't grow around here, and I’ve never seen them. So, I won't address them.

Here’s the rundown on these three:

All three:
Erect, non-twining, herbaceous plants with leaves even-pinnately compound, without tendrils or spines, growing up to 12 feet tall in a single year. The leaflets are entire and are not glandular-punctate. Flowers solitary or in racemes of 3-30 flowers. Fruits are non-segmented, several seeded.

If they have fruit (seed pods,) it’s easy!
The seed pods on Rattlebush (Sesbania drummondii) are about 2 - 3 inches long, 4-sided, winged, and typically have 3-7 seeds per fruit, while Big Pod Sesbania (S. herbacea) has seed pods that are much longer and narrower, do not have wings, and each pod has many tiny seeds. Bladder Pod (S. vesicaria) has seed pods that are about the same size as those of Rattlebush, but they are two-sided, without wings, and usually have 2 seeds per fruit. In Bladder Pod, as the seedpods mature, they separate into a thicker outside layer and a papery- thin, inside layer, which is also quite distinctive.

If fruit has not yet appeared:, the flowers are still quite recognizable: Bladder Pod usually has several flowers in short racemes, but sometimes the inflorescence is a solitary flower; flowers are reddish brown to orange or yellowish, often tinged with pink or red. Each flower is 6-9 mm long; usually there are 1-6 flowers per raceme, but occasionally up to 12. Big Pod Sesbania has yellow flowers, 2-6 per raceme. Rattlebush has yellow flowers, sometimes with red lines, 10-30 per raceme.

Posted by lisa281 lisa281, December 06, 2018 02:13

Comments

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This is a great journal entry, Lisa! Excellent job! :)

Posted by sambiology about 1 year ago (Flag)
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Thanks, Sam!

Posted by lisa281 about 1 year ago (Flag)
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This article is helpful to me. Thanks for sharing.

Posted by connlindajo about 1 year ago (Flag)
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@connlindajo Your welcome! I'm glad you found it helpful!

Posted by lisa281 about 1 year ago (Flag)
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Posted by billarbon 4 months ago (Flag)

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