Seed of the Week: Desert Senna

Our wrinkly mystery seeds from last week were from desert senna, Senna covesii.

Often it is the desert senna’s bright yellow flowers that catch your eye, standing out against the gray-green foliage.

You might also “hear” the flowers because the bees that are attracted to them buzz pollinate, hanging onto the anthers and making a loud buzzing noise to vibrate the pollen loose.

You can even hear the plant when there aren’t any bees. As my friend Lynne points out, “You usually hear it before you see it. It can be in a non-blooming stage and you won’t notice it but you hear it rattle.” That characteristic has led to common names such as rattleweed or rattlebox.

The sound is produced by the loose seeds rattling in the seed pods. Eventually the pods split open, releasing the seeds. The open pods stay on the plant for some time.

Desert senna is native to the Southwest, so it doesn’t require much water. It is a low-growing perennial, reaching about two feet tall.

In addition being attractive to bees, desert senna is also a host plant of the cloudless sulphur butterfly. It would make a wonderful addition to butterfly gardens.

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Thank you to Lynne for all her help and contributions to this post.