#marcescence

Pinwheel mushrooms are often overlooked not because of their size but because of their tendency to completely shrivel up and dry out in dry conditions, blending into the leaf litter. They can fully dry out over the course of the day, appearing dead, and restore completely to their original state just a few minutes after being submerged in water. 

The image below left was taken of a pinwheel mushroom (though not a purple pinwheel) just after a rain and the image below right was taken around noon the following day

This property was named “marcescence” by Elias Magnus Fries. The purpose has not been fully explained but it is possible that it is to maximize spore release when conditions are more favorable.

It’s simply a matter of marcescence

As you can see, the oak trees on are property are finally coming to terms with detachment. Shaken by the last gasp of autumn, their leaves are just now accepting the inevitable.

So why are oak leaves always the last ones to surrender to gravity?

The Internet says it’s because the abscission layer on oaks does not completely form until spring, allowing them to hold on to their leaves much longer than other trees. The botanical term is “marcescence” (withering without falling).

#365daysofbiking Defying gravity:  

Sunday January 31st 2021 – Some trees have a property, and it’s mostly, but not exclusively oak trees - that they do not drop lair leaves when they die off in autumn.

Instead, the tree keeps the leaf attached, shedding it the following spring.

The behaviour is called ‘Marcescence’ and scientists don’t really know why it occurs. It may be to protect leaf buds from browsing animals like deer, or to faster recover nutrients from the dead leaves by absorbing them back into the tree directly, rather than through the soil.

Whatever the reason, it’s very curious.

From my walk this morning

Selections from the Boise Biophilia Archives

For a little over a year now, I’ve been doing a tiny radio show with a friend of mine named Casey O’leary. The show is called Boise Biophilia and airs weekly on Radio Boise. On the show we each take about a minute to talk about something biology or ecology related that listeners in our local area can relate to. Our goal is to encourage listeners to get outside and explore the natural world. It’s…

Lower Miller Canyon.

Several of the oak species here are marcescent, that is, they are tardily deciduous and hold on to last year's leaves until new leaf buds and catkins are ready to emerge. The result is a show of off-season fall colors in spring.

The plant communities in our sky islands form a kind of layer cake of distinct biomes. On a north-facing slope desert grasslands give way to an assemblage of oaks and chaparral at about a mile in elevation (1600 m). At about 6000 feet (1800 m) pine species are introduced. On south facing slopes the progression is a bit slower due to differences in temperature, but if you pay attention to the trees on your mountain hike, you can easily gauge your elevation gains.