Sorry about the two day midweek break in BPotD — it wasn’t intentional, but something came up that needed all of my attention.
Another thank you to Orthotrichum@Flickr (aka Bob Klips) of Ohio, USA for sharing one of his photographs (original image via the Botany Photo of the Day Flickr Pool). If you’d like to enjoy more of Bob’s photographs and nature writings, visit Dirty Trees: Bob’s Brain on Botany.
Bob’s written about these intriguing fungi in the comments associated with his photograph, so I’ll quote him to start: “The ‘hat-tossing’ zygomycte fungus Pilobolus… decomposes the droppings of grass-eating herbivores. It is spread by the passage of spores through the animal’s digestive tract. Each sporangiphore [spore-bearing structure] aims toward the sun while it is low on the horizon, and propels the mass of spores up to a meter away from the dung.” The spores then stick to the foliage of nearby plants, ensuring they will be ingested and transported by the next hungry herbivore.
The Plant Pathology lab at Cornell University has an 18-hour time lapse movie of Pilobolus crystallinus. With photographs taken at 1-minute intervals for the final third of the movie, it is easy to see that the sporangiphores immediately collapse upon spore ejection. Perhaps this is unsurprising, given that the internal pressure prior to expulsion builds to somewhere between 2.8 to 5.6 kg/cm2 (40-80 psi). For the math behind this figure, see John Tuthill’s May 2005 paper, Evaluating the explosive spore discharge mechanism of Pilobolus crystallinus using mechanical measurements and mathematical modelling (PDF).
Or, for a poetical ode to Pilobolus crystallinus and Dr. Seuss, see The Fung in the Dung, via Tom Volk’s Fungi web site.
UBC Botanical Garden Resource Link: local photographer Jay Black (aka The Blackbird@Flickr) recently spent some time in UBC Botanical Garden and took this series of photographs of a rufous hummingbird in the Garden that you may enjoy. Also, he’s made the most inventive photograph of the tunnel connecting the two main areas of the Garden that I’ve seen to-date.