Cathy Ludden Around the Grounds, Native Plants

The All-American Shamrock

Legend tells us that St. Patrick used a shamrock, with its three leaves on a single stem, to teach ancient Celtic peoples about the Christian trinity. There is no agreement among historians, theologians, or botanists, however, as to which specific plant is the legendary Irish shamrock.

Some believe St. Patrick’s shamrock was one of several species of clover (Trifolium spp.) native to Europe and Britain. Others claim that the true Irish shamrock is in the family Oxalis, perhaps due to a report from a 16th Century Englishman who wrote that the Irish ate “shamrocks,” and plants in the Oxalis family were known to be edible. Adding to the confusion, the Irish word “seamróg” means “little clover.”  

Today, in honor of St. Patrick’s Day, several Oxalis species are sold as shamrocks both here and in Europe, which just annoys those who insist the traditional shamrock is a clover. In 1988, someone conducted a public opinion poll in Ireland asking which plant is the true shamrock, and the results split among several plants, including two varieties of clover and at least one Oxalis, with no real majority view.

In any case, St. Patrick’s Day seems an appropriate time to nominate an American native plant as the New World shamrock. Yellow Wood Sorrel (Oxalis stricta) is sometimes called “sourgrass,” “pickle plant,” or adding to the general confusion, “lemon clover.” As a candidate for St. Patrick’s Day shamrock, Yellow Wood Sorrel certainly looks the part. 

Yellow Wood Sorrel in bloom
Photo: Ansel Oomen, Bugwood.org

Yellow Wood Sorrel is useful, maybe even pretty if you look closely, and it is found absolutely everywhere. Yes, it is a weed! You’ve probably pulled it out of your lawn, your garden, your containers, your driveway or sidewalk — maybe without knowing or caring what it is.

Like many other weeds, Yellow Wood Sorrel grows in a wide variety of habitats – sun or shade, dry or wet, and rich or poor soil. Each of its 3 leaves has a fold down the middle. At dusk, the leaves close up and stay that way until warmed again by the sun.

The little yellow flowers have 5 petals and bloom from spring through late fall. The plant produces lots of seeds in capsules that stand upright above the foliage. When the seeds are ripe, the capsule explodes, throwing seeds up to 3 feet away! 

Oxalis stricta leaves fold up at night like little pleated skirts
Photo: Courtesy of Pixabay.com 

Yellow Wood Sorrel is edible, though in very large quantities it may be mildly toxic. You really should try clipping some tender leaves, or the little yellow flowers, and sprinkling them like micro-greens on top of salads, fish, or chicken. The taste is like lemon, sour and a bit bitter, but refreshing. Tender stems and leaves may be steeped in hot water (a handful of leaves per pint of water) to make a lemonade-type drink high in Vitamin C.

Bees, butterflies, and ants make use of the flowers of Yellow Wood Sorrel, and its long season of bloom means the flowers are available throughout the nectaring season. Perhaps we should be grateful that this weed provides some wildlife benefit by stubbornly popping up in even the most manicured suburban landscapes.

Yellow Wood Sorrel is a small weedy plant that grows everywhere
Photo: T. Webster, USDA, Bugwood.org

So, the next time you find yourself pulling Yellow Wood Sorrel from all the places it doesn’t belong, think of it as shamrock and then save a few leaves for your lunch. Sláinte!

THIS BLOG IS AUTHORED WEEKLY BY CATHY LUDDEN, CONSERVATIONIST AND NATIVE PLANT EDUCATOR; AND BOARD MEMBER, GREENBURGH NATURE CENTER. FOLLOW CATHY ON INSTAGRAM FOR MORE PHOTOS AND GARDENING TIPS @CATHYLUDDEN.
Cathy Ludden Around the Grounds, Native Plants

A Cabbage By Any Other Name

Guest post by Travis Brady

Just because a plant has an unpleasant name, doesn’t mean that it lacks aesthetic appeal or wildlife benefits. Such is the case with native Skunk cabbage.

Skunk cabbage, (Symplocarpus foetidus = clustered fruit that is fetid) gets its name from the unpleasant carrion-like odor it emits. This scent is a way for the plant to attract pollinators that are lured to rotting meat. The scent is especially noticeable when the plant is injured; but don’t let that deter you from experiencing the unique beauty and utility of this native!

Skunk Cabbage (Symplocarpus foetidus), as it is lovingly known, is one of the very first plants to push up from winter’s frozen ground and is a native flowering perennial.

Often emerging in late February, the maverick skunk cabbage uses thermogenesis, the ability to use stored energy to create its own heat (up to 70 degrees F)  in order to melt through frozen ground and snow. As one of the year’s first flowering plants, skunk cabbage, usually found in old woodlands, wetlands and along streams, is a haven for early season insects. If you stroll down to the vernal pond here at the Nature Center, you can spot skunk cabbage along the wooden bridge and all throughout the wetland area.

The unique flowers appear before the leaves emerge and are characterized by a mottled maroon hood-like leaf called a spathe. Deep inside the spathe is a knob-like structure called a spadix. The spadix is actually a fleshy spike of many tiny flowers packed together. 

A burning sensation caused by oxalate crystals inside the plant may keep deer and rabbits from foraging on the leaves, but skunk cabbage is known to be sought out by bears just emerging from hibernation. In addition, turkey and geese also eat the young leaves, and the seeds from the fruits are eaten by squirrels, wood ducks and quail. 

After the flowers fade, the leaves take over. Dark green in color, the leaves are quite substantial, reaching a foot and a half wide and almost two feet long. With seeds often dropping adjacent to the parent plant it is most likely that you will see patches of skunk cabbage rather than isolated individuals.

This truly striking, bizarre, and fascinating plant is tolerant of soil ranging from slightly acidic to slightly alkaline and makes an exciting addition to any garden that has the right conditions. By providing early season growth with colorful flowers and attracting a litany of pollinators, skunk cabbage can benefit your garden, and may be just the right plant to help you daydream about warmer spring days ahead. Henry Davis Thoreau sure thought so…

“If you are afflicted with melancholy at this season, go to the swamp and see the brave spears of skunk-cabbage buds already advanced toward a new year…” “See those green cabbage buds lifting the dry leaves in that watery and muddy place. There is no can’t nor cant to them. They see over the brow of winter’s hill. They see another summer ahead.” –Henry David Thoreau

Cathy Ludden Around the Grounds, Invasives

Evil Ivy Over Everything

We have a big problem at the Nature Center. And we are not alone. 

Ivy (Hedera spp.) – English Ivy, Irish Ivy, Persian Ivy – causes enormous damage to trees, buildings, and forest ecology throughout the United States. Maybe you’ve already seen Ivy pull stucco, mortar, trellises, and rain gutters off of buildings, or cause wooden siding to rot or attract mold. At least those things can be repaired. 

The damage Ivy causes in nature is much worse. It climbs trees, slowly strangling them to death by stealing light and water, and it weighs down their weakened branches until they break and fall during storms. It crawls across the ground, sending out roots to take up all available nutrition. And it smothers the ground with its evergreen leaves so other plants cannot establish or find enough light to survive.

Ivy chokes trees by stealing light, air, and water
The weight of ivy breaks trees already weakened by choking vines

Forests in our region were once populated with hundreds of different species of shade-loving plants: ferns, grasses, and a huge variety of wildflowers. Those plants fed thousands of species of insects, birds, and animals. Of course, development and too many deer have contributed to a tragic loss of these species, and so has the introduction of invasive plants. Ivy is one of the worst offenders.

A healthy forest is filled with great diversity of plants
Ivy eliminates other species on the forest floor

There is nothing wrong with English Ivy — in England! It doesn’t overrun woodlands in Europe because it evolved there, and European insects and animals eat Ivy and control its growth. 

In America, there are no natural controls, no insects or other animals to keep it in check, so Ivy becomes invasive. It out-competes native plants, leaving the forest depleted and sterile. Nothing here eats Ivy, so when Ivy is all that is left in the forest, there is nothing for forest animals to eat.

Some birds eat berries produced by Ivy and scatter the seeds, which can spread Ivy from garden to forest. But humans are much more culpable. Ivy is unfortunately popular with humans because it is evergreen, grows very fast, will live in sun or shade, and can cover a lot of ground or a wall very quickly. But it is also very difficult to control once it is established. Cutting vines at the base, applying herbicide to cut stems, and digging out roots can help save trees, but diligence is required to prevent this very aggressive pest from trying again.

Ivy is trying to attack this tree again

There is no true Ivy native to North America. But there is a beautiful native plant that makes a great substitute for Ivy. If you want a climbing vine to cover a wall or an arbor, or you’re looking for a groundcover for a shady area, try Virginia Creeper (Parthenocissus quinquefolia). It is fast growing, and it has glorious fall color. Its leaves are the host plant for the very interesting Sphinx moth – the native insect that acts as a natural control preventing this vine from taking over the forest. Virginia Creeper will wind its way up a tree trunk, but it won’t kill your trees.

Virginia creeper evolved here, and belongs in our woods – photo courtesy of pixabay.com

Don’t be confused by the common names of Boston Ivy (Parthenocissus tricuspidata) and Poison Ivy (Toxicodendron radicans). Boston ivy is not from Boston and it’s not an Ivy. It is an Asian vine in the same family as Virginia Creeper. Though it is not as destructive as Ivy, it actually can grow faster and taller than Ivy and completely cover a building in no time. Poison Ivy is not an Ivy either. It is a native vine and, interestingly, it is only “poison” to allergic humans and not at all to other animals. It actually has a lot of wildlife value to birds and other animals. If it’s not in your immediate area, you could consider admiring its beautiful fall color from afar!

In the coming years, the Nature Center has a fight on its hands. We want to remove Ivy from our 33 acres of woods. While some areas are only partially affected, and we work hard to keep Ivy off of our trees, there are large sections of our forest totally overrun with Ivy. We will be formulating plans for an Ivy-removal program this year, but it will be difficult and expensive. If you would like to help by making a contribution, please visit our Donate page here.

This blog is authored weekly by Cathy Ludden, conservationist and native plant educator; and Board Member, Greenburgh Nature Center. Follow Cathy on Instagram for more photos and gardening tips @cathyludden.

Cathy Ludden Around the Grounds, Native Plants

Forever Green: Native Groundcovers That Stay All Winter

Given our recent weather, you may well ask, “why should I care whether a ground cover is green if it’s under a foot of snow”? Fair question! 

In our milder winters, when snow comes and goes, evergreen groundcovers do offer structure and winter interest in the garden. And they benefit birds and small mammals, providing cover from predators and shelter from icy winds. But not so with ivy or pachysandra! Both are invasive, non-native plants that must be prevented from running into wooded areas where they smother everything! Fortunately, there are native evergreen groundcovers much better suited to our landscapes and helpful, rather than harmful, to the ecosystem.

We recently described Leucothoe, a native evergreen that can replace pachysandra as a ground cover under trees and shrubs and in wooded areas.

Another evergreen woodland plant we love is Christmas fern (Polystichum acrostichoides). Not truly a groundcover, because it stays in place rather than spreading itself around, Christmas fern can be planted densely to fill in a shady area. Deer won’t eat it, and it’s such a pleasure to see a green fern in the dead of winter.

Evergreen Christmas fern brightens the winter landscape

Perhaps the best known native evergreen groundcover in our region is Creeping Juniper (Juniperis horizontalis). Juniper is a versatile shrub that provides significant value for wildlife year-round. Its dense branches provide good hiding places, and its berries feed the birds. It prefers dry soil and full sun, but it tolerates some shade as long as the soil is well-drained. It spreads at a moderate rate, and effectively suppresses weeds. Juniper is also tough — it handles being buried by snowplow build-up, even with road salt! It’s a good choice for curb-side plantings and along sidewalks and driveways.

Creeping Juniper is attractive all winter along a property line

You can see another of our favorite evergreen groundcovers in the foundation planting at the Nature Center’s Manor House. Carex laxiculmis ‘Hobb,’ often sold as ‘Bunny Blue’ sedge, is a great groundcover for shade. It’s maybe more “everblue” than evergreen, so its eye-catching color is striking around and under shrubs, and even under shade trees. It will live happily with dense tree roots and spread itself slowly by short runners that sprout new little plants over time. It holds its blue-green strappy leaves all winter long. You don’t have to cut it back in the spring, but if it looks a bit ragged, you can trim the old leaves before new growth begins. Like most grasses and sedges, it is avoided by deer.

‘Bunny Blue’ sedge in winter under shrubs at the Manor House

Plant ‘Bunny Blue’ sedge with other native shade-lovers for a mix of textures. When the other plants go dormant in the fall, ‘Bunny Blue’ will hold the spot until they return

‘Bunny Blue’ sedge in summer in with Maidenhair Fern and Wild Canadian Ginger 

For a sunny area, we like Waldsteinia (or Geum) fragaroides, commonly called “Barren Strawberry” because its leaves look similar to strawberry, but it doesn’t bear fruit. Waldsteinia is a deer-resistant evergreen groundcover that likes sunny dry sites and blooms in early spring with bright yellow flowers. It only gets a few inches tall, so it’s great at the front of a flower bed. We planted it last year at the very front of the Nature Center’s new Pollinator Garden. Be sure to come see it bloom this spring!

Spring growth covers bronzed winter foliage of Waldsteinia

Waldsteinia spreads slowly by shallow runners. Use it around a mailbox or lamp post, or along a sunny path. Snow cover and freezing cold do not bother it, and it is hardy to Zone 4. Its leaves may turn bronze by late winter, but new growth will cover the old in spring and form a weed-suppressing mat. And when April showers bring May flowers, you’ll want to be there.

Waldsteinia blooms in late April to early May

This blog is authored weekly by Cathy Ludden, conservationist and native plant educator; and Board Member, Greenburgh Nature Center. Follow Cathy on Instagram for more photos and gardening tips @cathyludden.

Cathy Ludden Around the Grounds, Native Plants

Lookin’ Good, Leucothoe!

Leucothoe has a lot going for it:

It is a beautiful, flowering, evergreen, deer-resistant, low-maintenance, native shrub. It works very well as a foundation plant, groundcover, hedge, tree-underplanting, or pathway lining. With all these virtues, why is this excellent plant so under-used in our suburban landscapes?

Maybe it’s because nobody knows how to pronounce it? We’ve heard it said:

Lew-COE-tho-way, Lew-COE-tho-wee, and LEW-cuh-tho – and all those from experts! We favor the first choice, but if you’re shopping for it, the nursery staff likely will understand any of those options.

Or maybe Leucothoe suffers from the horrifying Greek myth behind the name? Poor Leucothoe was an innocent young woman whose father punished her, for entirely wrong reasons (look it up!), by burying her alive, whereupon she turned into a plant! Of course, it wasn’t this plant, because this plant is native to the Eastern US, and the ancient Greeks didn’t even know it existed.

Leucothoe in early summer with Christmas fern

Whatever the reason, Leucothoe definitely should be better known. There are actually two species of Leucothoe native to the East Coast. Leucothoe fontanesiana ranges from Louisiana to New York, while Leucothoe axillaris naturally appears only as far north as Delaware. It is not easy to tell the two species apart, and there are cultivars with fancy leaf colors derived from both. We see Leucothoe axillaris sold here frequently as Coast or Coastal Leucothoe. Leucothoe fontanesiana tends to grow a little taller, so read the nursery tag to see what the grower indicates for size.

So why should you know this plant? Leucothoe is beautiful, with gracefully arching stems and shiny, evergreen leaves. It is easy to grow, and incredibly useful. It typically grows about 3 feet high, and slowly spreads wider. It is naturally an understory plant, so it is happiest in shade, but will live in sun if it has enough moisture. Leucothoe is perfect as an evergreen ground cover, especially near wooded areas where pachysandra or ivy would pose an invasive threat. It will retain moisture and suppress weeds, so you can use it instead of mulch around trees or shrubs. 

Leucothoe in winter as an evergreen ground cover

Leucothoe evolved growing in the relatively mild winters of Southeastern forests. It is a Zone 5 to 7 plant, so it should be protected from the coldest winter wind. You can use it as a foundation plant on the shady side of the house and not worry about having to prune it for size. It can drape over a stone wall or define the edge of a garden path. Pro tip: although sold in nursery pots with instructions to plant in a hole the same depth as the pot, we find Leucothoe likes to have its roots spread out wide and shallow, which makes it easier to plant around established trees and shrubs, too.

Leucothoe is great under trees and larger shrubs

Leucothoe flowers in late spring with little white bells that look like lily-of-the-valley, though the leaves hide the flowers to some extent. New leaves emerge in red or bronze shades before turning deep green. In winter, the shiny green leaves are very welcome. 

Leucothoe survives heavy deer predation in a local park

Did we mention deer-resistant? We have found Leucothoe thriving in the woods in winter in areas known to be major deer hang-outs. And on our grounds at the Nature Center, Leucothoe is the only native woodland plant that really holds its own against the invasion of English ivy. 

On the forest floor, Leucothoe fights back against invasive ivy and burning bush

So, consider Leucothoe as a native substitute for English ivy, Japanese pachysandra, vinca, or wintercreeper – all known to be seriously invasive if they reach wooded areas. Leucothoe forms a shiny, dark green skirt for the base of trees, leggy shrubs, or fences. It looks good all winter, and will still be looking good when the daffodils bloom in spring.

Lookin’ good, Leucothoe!

This blog is authored weekly by Cathy Ludden, conservationist and native plant educator; and Board Member, Greenburgh Nature Center. Follow Cathy on Instagram for more photos and gardening tips @cathyludden.