Roses pt. 4- Invasive Introductions to the United States

Rosa multiflora. David G. Smith. 2009. http://www.discoverlife.org.

Roses are a gardener’s delight most of the time. What’s not to love about the beautiful flowers and heavenly scent? Maybe the thorns are a bit much, but every rose must have its thorn right? Well, some roses are a thorn in our side as horticulturalists, landscapers, and conservationists. Unfortunately, some roses have gone on to escape cultivation by throttling the underbrush of the countryside, particularly in the Southeastern United States. Their thorny nature and sprawling habit make them hard to pull out of unwanted places, and only come back when having been pulled out. Yes, unfortunately its true, some roses are a NIGHTMARE!

Some will never find anything bad to say about roses, but I for one have a problem with R. multiflora. The multiflora rose is a thorn in my side, as I often come across them having to weed garden beds. While the multiflora rose is not the worst offender when it comes to thorns, they grow relatively quickly. The plant is unassuming at first, being a weedy, thorny, sprawling rose, growing to be ten feet tall by fifteen feet wide at their largest. The rose flowers come in corymbs of small white single flowers or pink multiple flowers (this is another variety actually- v. cathayensis.) The plant spreads by its abundant seeds in the red hips that adorn the plant throughout the winter- birds love to eat them and spread them in their feces.

This rose was introduced from Asia in an environment quite like that of the Southeastern United States. Introduced as a conversation measure for erosion control, it quickly spread to being everywhere in the disturbed parts of the lower Appalachians. It is considered now a noxious weed, unfit for cultivation in its range. The flowers fragrance is not worth saving, as its too light to appreciate otherwise, and makes no impact when grown in cluster on the nose or the eye.

Rosa laevigata. Daderot. 22 April 2011. Wikimedia Commons.

Another rose that has been introduced, but is not as hated, is the Cherokee rose. This rose is from farther south in Asia, closer to Southern China, Taiwan, and Vietnam, giving it a limited hardiness range in the United States (generally to zone 8.) Where this evergreen climbing rose will grow, it will grow in abundance, but it is not beyond salvation. This rose has a very unique fragrance for a rose, almost as sweet as Gardenia, and makes for an excellent climbing rose on trellises. This rose tends to bloom white, with large identifiable blooms from a ways away, and nice yellow stamens, making for a brilliant impact.

This rose has been linked to the Trail of Tears in U.S. history, and more recently, has been featured in the Walking Dead. It is the state flower of Georgia (although if we were going to make any introduced flower the state flower of Georgia it should be the Crepe Myrtle, but I digress…) where it grows nicely.

Truth by told, many of the roses introduced could be invasive to the U.S. in one place or another. One example is the dog rose, R. canina of Europe, another favorite of English poets, as it grew very nearly everywhere in the countryside in its day. Its invasive to cooler parts of the Eastern U.S., but is not as noxious as the others above. This particular rose also has a nice rose scent, and its hips make excellent jams. Hopefully, the next post will wrap up roses as I do wild ones to the United States, then its on to lillies!

 

Mimosa (Albizia)

Albizia julibrissin. 2003. Michele Denbar. http://grannymountain.blogspot.com.

Summer is a season of rich scents, but none hits me so powerfully as mimosas do on a humid evening. Just as lindens are waning, mimosa takes full stage, casting its similar rich scent out through entire neighborhoods for pollinators. Mimosa is a catch all for many small trees and large shrubs in the Fabaceae family with similar flowers and tree structures, but these are actually quite different from the other mimosas out there. The fragrance I believe is almost as effective as the Acacias of the tropical world, but without the thorns.

This mimosa is also called the Persian silk tree for its silky flowers, but in the U.S. its best known as mimosa (although not related to Mimoseae. The tree does happen to be native to Persia in its river valleys, but also appears all the way over to East Asia. Its the hardiest tree of its tribe, hardy to zone 6a, and flourishing in every space the climate allows it to grow. As it is a tropical plant introduction, it decidedly adds a tropical feel to temperate landscapes, resembling the Acacias of Africa, although smaller. It will grow to be forty feet tall in zones 7-9, but in zones 5b-6b, it barely makes it over twenty feet, with a larger spread to thirty feet. As it is borderline hardy, it is almost always the last plant to leaf out in my area (mid May), along with crepe myrtle. Its bipinnate leaves are stunning in their length, and like many other plants in the genus, close at night, folding down in appearance.

The flowers begin to appear about this time of year in June and can last up until late August, scenting the summer nights with an incredible fragrance. The flowers are what make these trees unique, as they are watermelon pink, very much like a puffball, and appear in clusters that are identifiable from far away. The ‘flowers’ are actually composed of many small flowers in a big puffball-like cluster. The individual flowers are small, with  small calyxes and corollas, but very large stamens up to two inches long. The flower nectar attracts bees and hummingbirds during the course of the summer, and at the end of the season produce seedpods characteristic of the Legume family.

The fragrance is almost indescribable in these, as its a center point between three fragrances. It seems to be the middle note between gardenia, sweet pea, and watermelon (or perhaps pomegranate…certainly fruity). Its a fragrance that begs for more, and I cannot resist it! Even a few flowers are enough to do the trick, but a whole tree bedecked in blooms is a true ambrosia. The scent is strong day or night, but seems to prevail in humid evenings.

There are many cultivars available of the species, but the standard are the pink blossomed kind, which are unfortunately invasive in the Southeast. I’ve seen many growing wildly in the foothills beneath the Great Smoky Mountains in Tennessee, and one would think it was the only flowering tree to grow in Knoxville if driving on the interstates in the city during its flowering period. Variants of this main species can have creamy yellow and white blooms, but this is generally uncommon. There is a redder variety called ‘Rosea,’ as well as a purple leaf variety called ‘Summer Chocolate.’ ‘Rosea’ is hardy to zone 5, and tends to end up as a twenty foot tree, while ‘Summer Chocolate’ is only hardy to zone 7, but is less floriferous.

I normally make a spiel about not growing invasive plants as standards, but this is one of the few exceptions I think we can allow for the sake of its scent. Do dispose of those seed pods though please!

Its hard to believe June is nearly over. There are so many plants I should have gotten to by now it makes my head spin, but I guess winter can always allow some catch up time, as unplanned for the bloom season as that is.

Late Spring Edition- Indolent Bloomers.

Sambucus canadensis. J.M. Garg. Wikimedia Commons.

As the days grow ever longer and the thermometer and humidity climbs up and up, I’m reminded summer is quickly approaching the Northern Hemisphere. While Memorial Day is the unofficial start in the States, and the Solstice the more official start, the real start to summer is subject to guess and preference. In any case, as the weather continually warms, scents put on a different character themselves, as everything seems to become more powerful. For the late-blooming ‘Miss Kim’ Lilacs, and Irises, this can be a good character for a garden. However, our friends with indolent compounds again remind us that heat is not always better. In fact, both Elderberry and Privet smell quite tolerable when caught on a breeze or on a cool day as compared to in warm, humid weather.

Elderberries are native to every continent except Africa (unless you count Madeira as belonging to Africa) and just about every climate imaginable as well. The main species is S. nigra, native to the majority of the Northern Hemisphere. All species make wonderful small trees and large shrubs, with edible berries when ripe, but the flowers are only slightly tolerable. The single flowers grouped together form large corymbs, looking like dinner plates when in full bloom. The fragrance is sweet but also slightly fetid, reminiscent of Chestnut blooms as the weather warms. The foliage also has a strange scent that is not particularly pleasant. In any case, a wonderful jam is made from the berries, as are the liquers made from the stems and berries, which carry very little of the fetid aroma that the live plant does.

Ligustrum japonicum. Kenpei. Wikimedia Commons.

Privet is a shrub that grows almost as commonly as elderberry, but without the edible fruits. Privets are part of the Olive family, a family known for its scented species, and this one is certainly well represented. Like elderberry, it has a scent tolerable in small doses and in the right environment- otherwise its just a recipe for a headache. Its sweet enough but with a rank indolent kick that cloys too quickly. While there are several species, L. japonicum is the most widely grown in America, and grows naturally in California and in the South. It is particularly well adapted to the Southeast, and becomes invasive from the Appalachians south to the Coast, growing in many forests and byways of the region. The plant itself forms a nice hedge and grows densely to screen out unwanted views. It is an evergreen, hardy to zone 5b.

The season marches on! Its nearing summer here and I’m still behind for May, but what does one expect for a month brimming with life?

Russian olive and relatives

Elaeagnus angustifolia. P. Breen. http://www.invasive.org.

For a genera that has produced several of the world’s noxious weeds, this happens to be one of my favorites for two reasons. The first is obviously the fragrance, or else I wouldn’t be writing about it, the second is that because its roots fix nitrogen- it can grow anywhere and remediate soil. For a small list of the invasive species in this genus: Silverberry, silverthorn, and Russian Olive are all covered here. The majority of the species is of Asian origin, save for a few species from The Caucuses and Southeast Europe around the Black Sea, and one species from North America. Also the majority are fragrant late spring to early summer bloomers, the one exception here being Elaeagnus pungens. The scent varies between species but it is always sweetly fragrant, often to the point of being a solid nasal knockout.

The most attractive species of the group is easily the Russian olive, Elaeagnus angustifolia. Its called the Russian olive as it was thought native to the area of Southern Russia and Georgia around the Black Sea, but actually is native to Western Asia and Iran. In any case, the tree has beautiful silver foliage, small fruits, and yellowish flowers that are abundantly sweet. The sometimes gnarled trunks often give it a look similar to olive trees from a distance, hence the name. It is also very drought tolerant, which is why it is invasive in the Southwest U.S., growing in many floodplains from Texas to California. The small fruits are edible and sweet, although mealy.

Elaeagnus umbellata. Nathan Soley. 2011. Phytoimages.siu.edu.

Next is Japanese silverberry, Elaeagnus umbellata. While this sometimes is a gnarled, small specimen tree in my hometown of Lexington, it is actually a noxious weed in several Southeastern states, and I can attest to it being a weed in Appalachian Kentucky as well. This tree happens to be a noxious weed in West Virginia, the next state over from me; and it grows everywhere there, filling the mountains with a very refined sweet odor in late April and early May. There happens to be one specimen growing outside Bluegrass Community and Technical College on Euclid Avenue, which sheds its scent all over the campus on a windy day. The scent is very sweet, almost overpowering, but not cloying, its similar to Gardenia, but more honey-like. The small tree is pretty when bedecked with flowers, but the flowers themselves are quite small, and the leaves not very attractive- thus its best feature comes down to soil rejuvenation, which is how it was introduced as a weed to begin with. The fruits are sweetly tart and edible, but small, and more likely to be eaten by birds first.

Elaeagnus pungens. Aleem. http://www.thelovelyplants.com.

Lastly, the thorny olive or Silverthorn, is another noxious weed of the southeast. It happens to bloom in fall, from September until November, but is easily the most fragrant of all the species, with a scent strongly resembling Gardenia. It makes a nice Landscaping plant in areas in Zones 7-9, including on beaches. The shrub grows prolifically, sending up long, vining branches out scrambling up trees and shrubs in its way. It needs serious pruning not to look gangly. The fruits produced are silverish and inedible, and the flowers are not quite conspicuous enough to be attractive, but the mysterious autumn scent is enough to look past its skid row countenance.

Invasive and noxious plants should obviously not be planted in areas where they are invasive, so do consider this if you are hoping to grow any of the species above. Otherwise, enjoy the wonderful scent!