Peltate trichomes

I was in Delaware in March for a family reunion. Spring having emerged from winter the week before, there was much floral and insect activity.  All the usual suspects started blooming. I went into a thicket down my cousin’s backyard and found this plants with interesting leaves with brown spots all over underneath.

At first I thought it was some kind of infection, but the spots were too regularly distributed. Under the foldscope each of those brown spots had a fan-like structure and interestingly they always surrounded stomata .


Upon scanning the field, I found several developmental stages of this structure.  Video follows where I am discussing this with some kids.

It was then I remembered this remarkable post on Peltate trichomes by Manu, and his analysis on how this structure is used to trap moisture. See The physics of this process as explained by Manu is really interesting.

Currently based on my reading, I suspect this is a  member of the olive family (Olea), although the genus requires a bit more work, and another trip to Delaware. Dont forget to look under leaves, I have always found surprises.

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  1. Manu Prakash says:

    Wow wow wow!! What a remarkable find @Laks. Loved your curious explorations live.

    You are Igbo about the Trichomes. What’s interesting is that mechanically they have a “gate” like structure right under the Trichomes which opens because of the buckling of the Trichome in modifier (with capillary forces pulling it down). It’s remarkable that they are so mechanical.

    I had never thought about life stages – but it makes perfect sense for them to mature – since from a material properties point of view – you need the right stiffness to get the mechanism to work.

    Wonderful find 🙂


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