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I’m wondering what these star-shaped organisms are on a dead leaf I found in my backyard (Texas, USA). This was taken under my microscope at 40x magnification. They seem to be clear organisms with multiple outgoing “rays” that somehow benefit with being on the leaf. What’s the identification? Are they even organisms? They appeared stationary. Response to comment asker: The leaf did not feel hairy.

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These are stellate ("star-shaped") [and possibly peltate ("borne on a stalk")] hairs ("trichomes") of the leaf itself.

  • From Harris & Harris's (2001) ""Plant Identification Terminology: An Illustrated Glossary":

    Peltate. a flat structure borne on a stalk attached to the lower surface

    Stellate. Star-shaped, as in hairs with several to many branches radiating from the base. Figure 1686.

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    Trichome. A hair or hair-like outgrowth of the epidermis.

You can see a magnified image of stellate peltate trichomes on a leaf of a Texan native, Croton monanthogynus below:

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Leaf surface (abaxial) showing stellate, peltate trichomes. SOURCE: Nickrent, D.L., Costea, M., Barcelona, J.F., Pelser, P.B. & Nixon, K. (2006 onwards) PhytoImages. Available from: http://www.phytoimages.siu.edu

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    $\begingroup$ this looks like a cactus $\endgroup$
    – Féileacán
    Jan 12 at 18:20
  • $\begingroup$ @Féileacán I don't believe common species of cacti have stellate hairs. See nature.com/articles/ncomms2253 for an example. (Also, note: that cactus "hairs" you're used to observing are actually spines not trichomes -- specifically, spines that tend to be more delicate are called glochids. Trichomes on cacti typically associate with clusters of glochids for water capture, but such clusters of trichomes would appear clumped and apeltate unlike the imaged stellate trichomes. $\endgroup$
    – theforestecologist ♦
    Jan 12 at 19:01

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