Showing posts with label invasive species. Show all posts
Showing posts with label invasive species. Show all posts

Tuesday, March 17, 2009

Honeysuckle to Honey Locust

Ah, the first green leaves of spring...unfortunately, they belong to the invasive exotic, the bush honeysuckle. Bush honeysuckles are some of the most pervasive and difficult to eradicate invasive species in Indiana. They create dense shade that prevents native wildflowers and shrubs from growing; some species even release growth-inhibiting chemicals into the soil. The Indiana Native Plant and Wildflower Society (INPAWS) has a very informative flier that lists the ten most damaging invasive plant species in Indiana, including the bush honeysuckle and the Japanese honeysuckle vine:
http://www.inpaws.org/InvasivePlants.pdf
In addition to the early appearance of leaves, bush honeysuckle can be identified by the opposite branching pattern of the twigs and leaves (most of our native shrubs are alternate).
When walking through the forest sometimes you run across a tree with a strange lump, almost like a tumor. These woody outgrowths are known as burls (also known as burrs). No one is entirely certain what causes them, but it is believed that most are triggered when the tree undergoes some sort of stress - from certain types of mold or insect infestations, physical damage, and possibly genetic susceptibility. Some burls can grow quite large, and the wood is prized by artists and furniture makers for the unique and beautiful woodgrain patterns. The bark of the Cork Elm (Ulmus thomasii) is squishy, and indeed, very corklike! The bark grows in layers, typical of most elm bark. According to wikipedia, the Cork Elm is susceptible to Dutch Elm Disease, which may explain why we only seem to find a few small trees in the park.
If you're a tree hugger by nature, you might want to consider giving this tree a friendly, careful pat instead! These impressive thorny growths are found on the Honey Locust tree (Gleditsia triacanthos), making it a very easy tree to identify, even in the winter. The "honey" the tree is named for comes from the sweet pulp of the long bean pods the tree produces in fall, used for food and even fermented into beer by Native Americans. The pulp of the Black Locust tree bean pod is toxic, so be sure you have the right tree if you ever decide to taste it. Thornless varieties of the Honey Locust are often sold in plant nurseries for landscaping.

Monday, March 16, 2009

Semi-tame Wildflowers

Down the sides of the ravine between the EDC and the Peace Learning Center there are some not-so-wild wildflowers growing: the leaves of the familiar daffodil are poking up from the forest floor in good-sized clumps. Most of them were probably planted by the Lilly family (who built what is now the Peace Learning Center as a summer residence), and we have been told they are of an older variety not commonly seen today. Daffodils are are originally from Europe, Asia, and North Africa, and are not native to North America. Although they are an exotic species, daffodils are not considered to be an invasive species; they spread slowly, and do not outcompete the native wildflowers. Daffodils are also sometimes called jonquils or narcissus, and in the southern US they are sometimes referred to as buttercups, although "buttercup" can refer to several other species of flower as well.

Another non-native spring flower found in Eagle Creek Park, the bright electric-blue flowers of Scilla are easy to spot. The name is pronounced "Sill-uh," and it is also known as Siberian Squill. There seems to be quite a bit of variation in the common and even the scientific names - I've seen it called Scilia, Scilla siberica, and Scilla sibirica. Scilla is a member of the lily family, and, as the name suggests, came originally from Siberia. I wasn't able to find any information on whether they are considered invasive or not in Indiana, but I hope not - they're awfully cute! We found this one growing at the beginning of the Pin Oak trail in front of the EDC.

And yet another non-native early spring flower probably planted by the Lilly family: Snowdrops, also introduced from Europe. These hardy little white flowers are usually among the first flowers to bloom, sometimes even in February. They've spread to create large patches down the sides of the ravines just north of the Peace Learning Center.


Here's a close up of a snow drop bloom - when hanging down it is hard to see their beautiful green centers. This one had some tiny beetles living inside, and while I was watching, several bees and flies visited the other flowers to gather pollen and nectar.

The leaves of Virginia Bluebells were poking out of the ground near the same area as the Snowdrops. Some of them had a purplish cast, making them look like little cabbages. This one had some flower buds forming already - usually they don't bloom until later. Virginia Bluebell is actually a native wildflower to Indiana.


Wednesday, March 11, 2009

Monday Volunteer Walk March 9th Part 2

The leaves of the False Rue Anemone were poking out through the dead leaves on Monday - another sign of spring-to-come. Later they will create carpets of delicate white wildflowers. There is also a True Rue Anemone - not sure why this is considered to be the false one!


More early wildflower leaves peeking up through the forest floor - this three-lobed leaf is much thicker and sturdier than the fragile False Rue Anemone leaves and belongs to Hepatica. The leaf was thought to resemble the three lobes of the human liver, and thus, logically, the plant must be good for treating liver ailments! Hepatica is the Latin word for "liver," and another name for Hepatica is "Liver-leaf." This belief, that the appearance of a plant indicates its medicinal purpose, is known as the "Doctrine of Signatures."
We found the Hepatica growing along the stairs up the hillside leading to the old cabin. Not a pioneer cabin, although it is fun to pretend! This would be far too large and difficult to heat for a pioneer family. The cabin was built in the 1950's by the CEO of Indianapolis power and light (I still need to double-check the date, so don't quote me on that), and is constructed of old telephone poles!

Driving through the park in winter, it is easy to notice all of the young American Beech Trees (Fagus grandifolia) in the understory of the forest. Older beech trees drop their leaves in late fall, like most deciduous trees, but the younger beeches hang on to theirs for some reason. It is fun to hear the dry papery leaves rattle in the breeze, and they often are bent up in the direction of the prevailing winds by the end of winter. Young beech trees are able to grow in the shade, unlike the oaks and hickories, and so beeches, along with maples, are part of the mature Climax Forest of Indiana.
The long pointy leaf buds of the beech tree were formed last fall, and have been waiting patiently all winter for warm weather to come. They look quite dangerous and sharp, but don't worry - they're harmless (although I wouldn't recommend getting your eyes within poking range - look closely, but not TOO closely). You'll see a lot of my fingers in these close-up twig and bud shots - that was the only way to convince my camera to focus!


Another fun leaf bud - this one reminds me of a tiny fuzzy knife blade and is found at the tip of the Paw Paw, or Indiana Banana. I like to pet them - they are so silky soft! The round fuzzy bud further down the stem will open up in to a dark maroon, bell-shaped flower.

The strange and interesting twigs of the Winged Euonymus (Euonymus alatus), also known as burningbush for the bright red color of the leaves in the fall. The corky ridges are thought to be an adaptation to discourage browsing by deer.
Unfortunately, winged Euonymus (pronounced YOU-WAN-IH-MUS) is considered an exotic invasive species in our woodlands, brought over from northeastern Asia as an ornamental in the 1860's. When planted as a landscape plant away from forests it is usually not a problem, and there are several cultivated varieties that are less invasive and provide beautiful bright red fall color, but recent studies have shown that native trees and bushes are much more valuable to wildlife, especially birds, than the exotic species commonly used for landscaping. The key is in the BUGS!
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Native species are host to a whole community of caterpillars, beetles, and other invertebrates that are a vital source of FOOD for songbirds. Trees and bushes brought in from other parts of the world are missing the network of insects that have adapted to living with them in their home country. Although they provide some shelter, and some species may produce berries or nectar, their main value as an insect smorgasbord is missing.
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Planting native trees and bushes is a much better choice for wildlife. It is a gargantuan task, but we also attempt to control exotic invasive shrubs and bushes in our forests, so that native shrubs have a chance to grow. There are native varieties of Euonymus, although they don't have the nifty wings on the twigs. We'll have to see if we can find some growing this year.
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For some excellent reading on the value and importance of native plants to our declining bird populations, check out the book "Bringing Nature Home" by Douglas W. Tallamy: