Refuge Notebook • Vol. 9, No. 27 • August 10, 2007

Forest detective finally notices strange purple plants in muskegs, finds name, and more names by Ed Berg

princess Andromeda of Greek mythology, and it is in- deed a beautiful dwarf shrub in wetlands in the spring, with clusters of delicate pink urn-shaped flowers.

Exobasidium fungi. Credit: Kacy McDonnell/USFWS

The forest detective prides himself on noticing the small details of daily life in the natural world, and on Lowbush cranberry plants. The green shiny foliage knowing the names of a good many of them. He has, (background) is normal; the red foliage is infected with however, found that he probably will not see some- the juelianum, which changes the thing if he doesn’t have a name for it. color of the leaves but does not alter their basic shape. Take the case of this obscure purple plant (see (Photo by Ed Berg) photo with yellow background) that commonly grows in muskegs, along with Sphagnum peat moss, lowbush cranberries (lingonberries), blueberries and Labrador So, what then was this flowerless purple plant, tea. I had no name for this plant and must have over- with larger, flat deciduous-looking leaves? Normal looked it for years, until one day for no obvious reason Andromeda leaves are evergreen, with rolled edges, it caught my eye as something I couldn’t identify. This like Labrador tea. These plants couldn’t be related, was embarrassing, like meeting a familiar face and be- yet they were obviously growing together. I collected ing instantly aware that you have never known this more of the purple plants, and showed them to several person’s name. botanist friends, and even sent some to a plant pathol- I quickly set about digging up the plant to get a ogist. They all admitted that they had seen it, butno better look at it. The purple leafy stem was about6 one had a name for it. Finally a visiting Norwegian inches long, and it had simple soft, flat leaves about sphagnologist (a peat moss specialist) recalled that he an inch long. There were no flowers, and indeed it oc- had seen a name for this thing, and looked it up for me curred to me that I had never seen any flowers on this when he returned home. kind of plant. A single long stringy stem snaked down It turns out that the purple part of the plant is into the peat moss. I followed the long stem, deter- a caused by an infection of the fungus Exobasidium mined to dig up the whole plant, and to my surprise karstenii. The fungus takes over the plant’s normal found that the stem was connected to a nearby flow- growth mechanism like a cancer, and causes the plant ering bog rosemary plant. Bog rosemary has the sci- to produce larger, flimsier leaves of a purple color. entific name of Andromeda polifolia, for the beautiful Late in the season, black fungal spores can be seen on

48 USFWS Kenai National Wildlife Refuge Refuge Notebook • Vol. 9, No. 27 • August 10, 2007 the bottom of the leaves. The spores are dispersed by the wind to infect new host plants. Insects often produce galls on leafs and twigs to house their offspring, and the Exobasidium shoots can be thought of as a kind of gall. In both cases a for- eign organism takes over the growth mechanism of a plant and creates a new structure to facilitate its own reproductive success. Once I had a name for this condition, I started searching the literature, and found that there are many other species of Exobasidium that affect com- mon members of the heath family () in the North. Indeed, armed with more names I started see- ing more species of this type of fungus, which I had Crowberry plants. Upright purple stems are infected indeed never noticed. with the fungus Exobasidium empetri; the spiky green leaves (near the ground) are normal. (Photo by Ed Berg) For example, have you ever noticed the reddish purple leaves on blueberries during the summer? Blueberry leaves should be green during the summer, The Exobasidium fungal conditions don’t usually but the reddish purple ones are infected by Exobasid- kill the host. Indeed, in the world of parasites, it’s ium vaccinii-uliginosi (a name pirated from the scien- bad form to kill your host because the host is your tific name for blueberries Vaccinium uliginosum). meal ticket. Given the wind-blown spores, it’s not sur- prising to find many of the boreal forest Exobasidium Likewise, on lowbush cranberry I sometimes see species on both sides of the oceans. One recent study stunted shoots with small red leaves with white un- of the Exobasidium on bog rosemary and mountain dersides; this is Exobasidium juelianum growing on heather (Cassiope tetragona) in Europe found that the our much-loved Vaccinium vitis-idaea cranberries. (See frequency of infection increased at lower elevations, photo #2.) Lowbush cranberries also host Exobasid- suggesting that the fungus likes warmer temperatures ium vaccinii, which produces a gall-like thickened welt and that we may see more of it with increased climate with a red center on the leaves. warming. Have you ever picked the so-called “true cranber- Carl Linnaeus, the Swedish founder of modern ries” (Vaccinium oxycoccus) in muskegs? These plants -and-species scientific names, is quoted saying, have scattered large plump berries growing on thread- “If you do not know the names, your knowledge of like stems with tiny leaves. Kids love these cranberries the things perishes.” (Linnaeus, Critica Botanica, 1737). because they overwinter well, and can be picked in the This is well put, but I would add that without names, early spring. The leaves should be evergreen, but some our knowledge can’t even get off the ground, because of them are red with the fungus Exobasidium rostrupii. we probably won’t recognize that we are looking at something worth a name. There is more to seeing than Likewise, crowberry plants (in the Empetraceae meets the eye. family) often show a single stem with bright purple Ed Berg has been the ecologist at the Kenai Na- or red leaves among a sea of stems with green leaves. tional Wildlife Refuge since 1993. Ed will teach his This is Exobasidium empetri. (See photo). one-credit Cycles of Nature course at the Kenai Penin- A Google image search on the Internet will pull up sula College in Soldotna and Homer, beginning Septem- nice photos of many of these fungal conditions, espe- ber 11 and 13, respectively. Previous Refuge Previous cially if the search is not limited to English language Refuge Notebook columns can be viewed on the Web at sites. http://www.fws.gov/refuge/kenai/.

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