Preserving our Region’s Tree Legacy

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Preserving our Region’s Tree Legacy

Categories: Blog, Newsworthy

Powell Gardens horticulture staff went on an expedition last week to collect some special tree seeds.  We went to private property in Henry County, Missouri (the county just below us here at Powell Gardens) because we had permission to collect seed there.  The seeds were from a special native population of our state tree the Flowering Dogwood (Cornus florida).  Why are they special?  Because Flowering Dogwood does not grow wild over the entire state but is found mainly in the Ozarks and northward up the Mississippi River to Hannibal and up the Missouri River to around Boonville.  This outlying, native population is the closest to Kansas City and may represent the most northerly of the western strains of the tree.  It’s unique adaptation to our hotter, drier climate may be important to gardeners who sometimes struggle to grow this very ornamental tree.

Our collecting trip included Caitlin Bailey ,Senior Gardener on the Island Garden; Jesse Stauffer-Baum, Senior Gardener-Collections (both pictured above, posing before we entered the woods) and myself.

We found the Dogwood trees growing above and below a gorge of sandstone.  Many of the trees like the one pictured here were beginning to show fall color.  Flowering Dogwood is one of the first trees to start turning but its fall color lasts and lasts, beginning purplish and turning true red as the green chlorophyll disappears from the leaf (red and green make purple).  The red fall leaves finally drop in late October or early November.

Here Caitlin Bailey walks among the wild dogwoods as we hike down into the valley.  Caitlin lead the way as she was the one who discovered this dogwood population and got us permission to collect.  The dogwoods are the trees starting to turn fall color behind her, with a small tree in front of her as well.  The interesting topography made for challenging seed collection as we had to be careful not to fall off the cliffs!

Here’s a better perspective of the gorge, complete with all sorts of other flora from Pawpaws to ferns, mosses, liverworts, and lichens.

Here’s a picture of some of the extraordinary lichens and mosses found at the site.

Here’s what dogwood fruit look like.  They are bright red when ripe to attract the attention of birds.  They are very high in fats and help fuel bird migration and the diets of many songbirds.  It’s an interesting relationship as the birds need the dogwood for food and the dogwood needs the birds to disperse their seeds.

Reaching the Dogwood seeds often required some tree climbing.  Dogwood is one of our strongest woods and we would often pull down branches to where we could reach the fruit.  We had to collect 2,000 to 3,000 seeds.  Why so many?  Because our collection trip was not just for Powell Gardens’ plant collections.  The significance of this dogwood population is of our nation’s interest and the U.S. National Arboretum is preserving examples of Flowering Dogwood from throughout its range and wanted a collection from this population.  Their goal is to preserve the genetic diversity of this highly ornamental species with added significant value to wildlife.  I mailed off 3,000 of our collected fruits to the National Arboretum’ “Woody Landscape Plant Germplasm Repository” on Friday — volunteers there will clean the seed and prepare them for long-term storage which involves another step where they are sent to Boulder, CO where they are frozen and preserved indefinitely.

Here’s a closer look at collected fruit of Flowering Dogwood.

We had several hundred Dogwood fruit leftover for Powell Gardens collections and here Jesse Stauffer-Baum uses the handle of a knife to crush the seed, then he separates the pulp from the seed with the blade of the knife.  The seed requires removal of its pulp and soaking in soapy water plus cold stratification to germinate them as tree seedlings next spring.  In nature, birds do all this work, their digestive system removes the pulp while it helps to scarify the seed.  The seed is dispersed by the bird in its droppings, complete with some added fertilizer!  Winter will be its natural stratification but we speed up the process using our refrigerators.

Here’s what a first season Flowering Dogwood seedling looks like and YES, this one was collected by Caitlin from the same unique Henry County population last fall.  These seedlings show the best vigor and clean foliage of all our dogwood seedlings (see others in the background).  Another reason why the National Arboretum is saving samples of this tree from around the country is to protect the species against the disease Dogwood Anthracnose (Discula destructiva) which has killed many dogwoods, mainly in the cooler and wetter part of the species’ range.   The disease has not spread into wild Missouri dogwoods for unknown reasons: theories include our climate or we have naturally resistant strains of the plant.  Look for our 2014 seedlings to be available at a future plant sale or event so you to may try to grow this special local strain of Flowering Dogwood in your own garden.