Saturday, April 24, 2010
Like gardens and natural areas everywhere, the native plant gardens at Horton Park are lovely with the blooms of this very early spring. The shade garden has carpets of downy yellow violet; you can also see the delicate white flowers of false rue anemone and the drooping yellow flowers of large-flowered bellwort, also called merrybells. The serviceberries, the small trees we planted to provide more shade, are in bloom too.
The oak savanna gardens have golden alexanders about to burst into bloom. Next to the sidewalk the prairie violets have purple flowers and the pussytoes and prairie smoke are in full bloom.
Featured plant: bur oak (Quercus macrocarpa)
Today's featured plant is the bur oak. You can see one in flower in the smaller of the oak savanna gardens. Bur oaks don't generally produce flowers and fruits until they are about 35 years old, so you know this tree has been around for awhile. The flowers of bur oak are separate; what you see are the male catkins, which are long, graceful inflorescences producing many small brownish flowers without petals - they are pollinated by the wind. The female flowers are in much smaller catkins. When they produce fruits, you can tell a bur oak acorn by the fringed cap covering it. Bur oaks were once one of the most common trees in Ramsey County, occurring throughout the area in oak woodlands and oak savannas. They often grow far apart, so their branches tend to spread out and create attractive open-grown forms - great for climbing on. They have thick corky bark which is highly resistant to fire. This feature helps them survive in oak savannas, which burned frequently in the 1800s and earlier, both from lightning fires and from fires set by native people to produce good forage for the bison and elk that once lived here. Bur oaks also have deep tap roots, which help them find water even during droughts. If you visit the park, see if you can find two other bur oaks, smaller trees planted by the Friends of Horton Park in recent years - too young to produce flowers.