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Found yesterday. Puccinia poarum, (aecidial stage), growing on live leaves of Coltsfoot – Tussilago farfara. Apparently very common, but this was the first time I’d found it!
Spore measurements are slightly larger than Wilson & Henderson suggest for the aecidiospores of this species – but having checked my calibration yet again, (see calibration image below), – I’m confident that these measurements are correct.
PS: Could anyone explain, or suggest what the small “nodules” are, that can be seen on several of the spores?These little bumps were apparent on about half of the spores on the slide. (There were no similar looking things floating around independently of the spores in the water drop).
Click on images to view at full size.
[attachment=3]Puccinia poarum on Tussilago farfara 040615.jpg[/attachment] Aecidia, seen beneath the dense tomentum on the underside of the leaf.
[attachment=2]Puccinia poarum spores x400 040615.jpg[/attachment] Aecidiospores x400.
[attachment=1]Puccinia poarum Spores x400 040615 (Measured).jpg[/attachment] Aecidiospores x400 with annotated measurements.
[attachment=0]Calibration x400 – 040615.jpg[/attachment] Stage graticule with calibration measurements – correctly showing 100µ and 200µ as measured using “Micam” software.Regards,
Mike.
Hi Mike it won’t be the last time you see it! Do those nodules correspond to pores in the spore walls? Perhaps the spores are germinating – a useful trick is to mount in cotton blue in lactophenol, pop a cover slip on and heat the slide until it just starts to bubble, You will find that this procedure clears the spores somewhat, makes the pores much more obvious, and would also stain the emerging hyphae.
just a thought
Chris
Thanks Chris. I tried heating spores in lactophenol cotton blue earlier today.
As you suggested, it did clear the spores, but didn’t seem to produce any more obvious staining in the nodules.
Having said that, the leaf containing the aecidia had completely dried out in the interim, and I did struggle to get a reasonable number of spores – which then had to be rehydrated for some time before adding the lactophenol cotton blue.
Plus – I’m not sure whether my heating of the slide might have been a little too intense – I used a butane candle-lighter as heat source, but removed the flame as soon as I saw the liquid drop beginning to bubble under the cover slip.
Hopefully, I’ll find more fresh material, and if so, will try the heating process again.
Regards,
Mike.
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