Plant Physiology

Plant Physiology (Biology 327) - Dr. Stephen G. Saupe; College of St. Benedict/ St. John's University; Biology Department; Collegeville, MN 56321; (320) 363 - 2782; (320) 363 - 3202, fax; ssaupe@csbsju.edu

A Taste of Bryophyllum: A Trip Down Memory Lane

The Problem: In 1813 Benjamin Heyne wrote the following letter to the Linnean Society.

Dear Sir:
I had an opportunity some time ago of mentioning to you a remarkable deoxidation of the leaves of a plant in day-light. As the circumstance is in itself curious, and throws great light on the opinion of those celebrated philosophers who have written on the subject, I will state it shortly in this letter, which if you please, you may in extract, or in any way you think proper, lay before the Society. The leaves of the Cotyledon calycina, the plant called by Mr. Salisbury Bryophyllum calycinum, which on the whole have an herbaceous taste, are in the morning as acid as sorrel, if not more so. As the day advances, they lose their acidity, and are tasteless about noon; and become almost bitterish towards evening. This is the case in India, where this plant is pretty generally cultivated in our gardens and it remains to be seen if the same takes place in the hot-houses in England, where it has been lately introduced.

Case Study:

Leaves were removed in the morning (about 7:30 am) and late afternoon (about 4:00 pm) from the leaves of two species of Bryophyllum, also called Mother of Thousands. Break open a leaf and touch it lightly to your tongue for a quick taste. Can you tell which leaf was collected in the morning and which in the evening?

Now, write a letter to Mr. Heyne describing our current scientific understanding for the observations described in his letter.

Reference:

Thanks to Dr. David Walker (http://www.daw.exl.co.uk/) for sharing the letter with the Plant Ed ListServe.