Oak Detective

We've been losing many of our oaks at the Arboretum.  We've also been looking for a reason for their death.  Sure, there are the customary oak problems, Armillaria and Phytophthora on some, Hypoxylon and ambrosia beetles on others, and every other combination you might be able to think of.  We've had all the experts look at declining oaks on the property, but so far, no pattern has been established to explain what is going on. 

I happened to be out looking at something else with Kevin, and he directed me to the north side of the Azalea Collections where I met a chain saw wielding expert from the Forest Service.  He had cut down a small chestnut oak, Quercus prinus, and had collected all kinds of samples.  It looked a bit like a crime scene with evidence collection taking place. 

Chris Carley, on the right below was there and has been a key player in bringing forestry types and plant pathologists to the Arboretum to collect data that might point to a cause or causes for the loss of our oaks.  He's also been monitoring our property carefully for emerald ash borer and Asian longhorned beetle.  I'm happy to report that neither have been found so far, but Chris's work as part of the American Public Gardens Association's Sentinel Plant Network is a key part of keeping ahead of new pest and disease problems.  

Even though we haven't found a pattern to the oak deaths, careful observation and data collection will help us understand what is going on.  It might be a natural cycle of death that is part of the progression toward climax forest, or there may be underlying causes that we can diminish to help our oaks survive.

Very Hairy



I bought a bunch of Achimenes this spring because I once had them and really enjoyed them, and they were easy to care for because they went dormant over the winter, eliminating the hassle of carrying them over under lights.  When I placed my order, I also got some Eucodonia 'Adele' rhizomes.  They have finally bloomed, and although lovely, the flowers aren't the main attraction in my opinion.

It's the leaves.  Pinkish red cotton-candy like hairs cover the underside of the leaves, pleasantly thicker at the veins.  The tops of the leaves have a bit sparser covering of white hairs.  

Makes you wonder what would drive this species to put so much of its energy into hairs.  I'm guessing that it foils insect pests since it is so much thicker on the underside of the leaves than it is on the tops.  I don't think it is protection from sun or water loss, since there isn't enough on the upper leaves to help filter strong light or prevent transpiration.



Rickrack Cactus and Comb Fern

Forest has been watering the deck plants now, and I've missed some developments.  The Epiphyllum anguliger, rickrack cactus or queen of the night,  has quickly budded in response to the longer nights and cooler weather.  It's burst into bloom to welcome autumn.  The fragrance is wonderful, and there will be many flowers this year.  I've loved this plant.  The cladodes (stems modified to function like leaves) do indeed look like rickrack, and they remind me of Grandma Aker's aprons, which were always adorned with rickrack. 

I did notice something amazing weeks ago.  The rickrack cactus has a pot mate.  Several years ago, I purchased a Schizaea dichotoma,comb fern, from Meehan's Miniatures at the Bonsai Festival.  It grew in a pot with another fern and promptly died when exposed to low humidity indoors.  Now it has inexplicably appeared in the very rootbound pot of the rickrack cactus.  It's an interesting fern.  The genus Schizaea is thought to represent a link between the whisk ferns and other ferns.  At any rate, it must be a very covert fern, since I never noted spores on the fern that died, and both a male and female gametophyte must have been growing with the cactus and united to form the new fern.  I've thought about putting it in another pot or terrarium, but I think I'll leave well enough alone.