Sunday, March 29, 2015

Pass the Mustard

I’m always impressed when I’m with an experienced plantsman and he/she is able to confidently announce that a plant we’re examining is part of a certain plant family: “Well, clearly this is in the Heath family, Ericaceae.” Details are not always given so I just nod appreciatively and write it down. When it comes to the Mustard family, however, the family resemblance is a bit more obvious and spring time is a great time to recognize it.

Brassicaceae is the scientific name for the mustard family.  It contains approximately 375 genera worldwide, about 55 of which are found in North America. The plants in this family are mostly herbaceous plants that are annual, biennial or perennial. Of course you know many of the plants from the edible world: mustard (Sinapis and Brassica), radish (Raphanus), cabbage/broccoli/ cauliflower/turnip (Brassica), horseradish (Armoracia),  wasabi (Eutrema), cress (Lepidium) and watercress (Nasturtium).

Four petals
Flowers of the Brassicaceae family are recognized by having 4 petals arranged crosswise, as in the shape of a cross (hence an older name - Cruciferae - for the family). 

They also have 4 sepals (the green leafy parts that enclose the flower bud and later surround the flower at the base when it is open). They have 6 stamens, 4 of which are long and 2 of which are short.  The flowers are often held in elongated clusters.

Sepals on Cardamine diphylla
Some of the more familiar ornamental members of the mustard family include Alyssum, wallflower (Erysimum), dame’s rocket (Hesperis matronalis), candytuft (Iberis), moneyplant (Lunaria), stock (Matthiola), and Nasturtium. The ornamental forms of these plants are not native to the US, although there are some species of them that are.

There are some exceptionally weedy, and in two cases invasive, members of the mustard family. Garlic mustard (Alliaria petiolata) is the worst, but certainly many of us have fought against the annual hairy bittercress (Cardamine hirsuta) in our own yards. 

Pepperweed (Lepidium latifolium) is an invasive plant in the western US.

Slender toothwort, Cardamine angustata

Notable among the springtime native plants that you will find are the toothworts. Formerly known as Dentaria, they are now considered part of the Cardamine genus. Four species of toothwort are found in Georgia: slender toothwort (Cardamine angustata), forkleaf toothwort (Cardamine dissecta, formerly Dentaria multifida), cutleaf toothwort (Cardamine concatenata), and two-leaved toothwort (Cardamine diphylla). All of them are found in north Georgia only and they are perennial.

Cardamine bulbosa

The native bittercress have a more statewide distribution. These include species like Cardamine bulbosa, Cardamine pensylvanica, and Cardamine parviflora. Only C. bulbosa is reliably perennial.

There are native species of rockcress (Arabis) and Draba in Georgia as well, two other family members.

A late summer blooming member of the mustard family in Georgia is pinelandcress (Warea). I was fortunate to see it in bloom on a field trip to the Fall Line Sandhills with the Georgia Botanical Society.

Seed pods forming

Once the plant sets seed, the seed pods can be long and thin (known as a silique) or short and broad (a silicle). Long thin pods can be seen on toothworts and bittercress. 

One source indicates that all members of the mustard family are edible (but they don’t always taste good). I can’t vouch for that, so please use caution. This same source says that crushed leaves have a similar smell for all members.

Mustard family members in general are rather weedy and short-lived. [As far as I’m concerned, toothworts are not nearly weedy enough but at least they are perennial.] Research on the abilities of mustard family plants to perform phytoremediation has shown some promise. Phytoremediation is a process of decontaminating soil or water by using plants to absorb or break down pollutants. Now perhaps I can finally feel good about those hairy bittercress weeds in my yard!

Sunday, March 22, 2015

Spring Trees - Alternatives

As I walked through my neighborhood the other day, my view was filled with blooming ornamental pears (Pyrus calleryana ‘Bradford’ and others). This neighborhood is about 25 years old and that was a popular landscaping choice then. Thankfully it is less popular now.   

American plum (Prunus americana) in late March

Ornamental spring-blooming trees from other places (Asia, Europe, etc.) are a big part of the selection available to the average gardener. Are non-native trees the only choices for spring blooms in the landscape? Of course, the answer is no. The wild lands of Georgia were full of spring-blooming trees long before Europeans arrived on these shores. Those native trees are perfect candidates for our gardens even today.

Red maple (Acer rubrum) – the earliest tree to bloom with small but numerous red flowers that provide pollen and nectar for early bees. Red maple is also very adaptable to a variety of growing conditions.

Redbud (Cercis canadensis) – pale purple flowers often peek out at us from roadsides, but this tree provides a beautiful shape in the garden and bees love the flowers too. Several cultivars are available.

Serviceberry (Amelanchier arborea and other species) – soft white blossoms flutter in spring breezes. These flowers turn into tasty fruit used by early settlers as well as highly sought after by birds.

Plums (Prunus americana and others) – white flowers are held close to the branch but they light up the tree because they are so numerous. Pollinated flowers become juicy small fruits favored by humans and wildlife alike.

Hawthorn (Crataegus sp.) – clusters of white flowers are joined by emerging leaves to create a pleasing effect. Clusters of bright red berries appear in summer and persist into fall, waiting for flocks of birds to discover them. Several cultivars are available.

Hawthorn (Crataegus viridis 'Winter King') at the elementary school nearby

Black cherry (Prunus serotina) – elongated clusters of creamy flowers provide a feast for native bees. Ripening berries beckon birds who often find tasty caterpillars too.

Sassafras (Sassafras albidum) – pale yellow flowers are held in clusters before the leaves emerge. Only female flowers turn into the showy blue and red fruits. The tree also provides one of the best fall color shows around.

Crabapple (Malus angustifolia) – southern crabapple flowers are pale pink and can be delightfully fragrant. Edible small fruits follow and were often used by early settlers.

Crabapple (Malus angustifolia

Red buckeye (Aesculus pavia) – is a small tree form shrub that is perfect for small spaces. The early flowers are an important source of nectar for returning hummingbirds and bees.

Fringetree (Chionanthus virginica) – the delicate white petals are especially showy on male trees, but it is the female that produces the dark blue berries in the fall. As a specimen tree, this one never fails to grab attention.

Pagoda dogwood (Cornus alternifolia) – a lesser known species of dogwood, this one has alternate leaves and an especially pleasing shape. Tiny flowers held in clusters turn into fruit that is much appreciated by birds.

Pagoda dogwood (Cornus alternifolia)

Flowering dogwood (Cornus florida) – a long admired ornamental tree, this is generally available as cultivars in nurseries. Tiny flowers surrounded by large white bracts turn into showy red fruits that birds love. Don’t be fooled by Kousa dogwood, it is not native.

Silverbell (Halesia sp.) - this small to medium tree is perfect for a specimen tree location. The showy white bells decorate a gracefully shaped tree.

Snowbell (Styrax grandifolius and S. americana) - similar to the silverbell, but the white petals are more open to show the yellow stamens.

Bigleaf snowbell (Styrax grandifolius)

Wow, that is a lot of choices once you write them all down! I hope that if you are looking for something native that you can find something on this list to suit you and your landscape conditions.

Sunday, March 15, 2015

Winning Weeds

About the time that the common violets (Viola sororia) started blooming this week, Doug Tallamy had an op-ed in the New York Times about essential plant/insect relationships. For those of you that haven’t heard of Dr. Tallamy and his entomological message about plants and insects, it’s a compelling tale. If you know about the monarch butterfly and its relationship with milkweed (Asclepias sp.) then you already have the gist of it.

Tiny bluets (Houstonia) can be found in thin grassy areas

The op-ed included a photo gallery of plants and wildlife (insects, birds, and others - beautiful pictures as always) that have a relationship with those plants. While some relationships were about wildlife that eat the plants’ fruit, others were about insects that use the plants as larval hosts: monarch butterflies and milkweed, zebra swallowtail butterflies and paw paws (Asimina sp.), and violets (Viola sp.) and fritillary butterflies.

Of course the common violet is considered a pesky lawn weed by many folks but it’s time that it and other “weeds” get the credit they deserve for their important role in keeping butterflies flying. Here are just a few of the butterflies that depend on plants that might otherwise be considered weeds:

Great spangled fritillary butterfly – Violets (Viola sp.)
American lady butterfly – pussytoes (Antennaria  sp.), cudweed (Gnaphalium sp.), and ragwort (Senecio sp.)
Spotted thyris moth – bluets (Houstonia sp.)
Skippers, wood nymphs and satyrs – native grasses (Panicum sp., Andropogon sp. and others)
Cloudless sulphurs – native legumes such as partridge pea (Chamaecrista sp.)
Gray hairstreaks, skippers and eastern tailed blues – tick-trefoil (Desmodium sp. and related plants)
Question mark, comma, painted lady, and red admiral butterflies – nettles (Urtica sp. and related plants)

Cloudless sulphur butterfly

The next time that you come across a "weed" and decide to get rid of it, you might just want to check whose breakfast, lunch and dinner it is. Some of these native weeds are real winners.

Red admiral butterfly

Now if you'll excuse me, I think I need to go find some nettles.

If you're interested in learning more about butterflies? Check out the North American Butterfly Association and its new Georgia chapter. 

Sunday, March 8, 2015

Connect the Dots For a More Natural Landscape

Trees are wonderful things and I love to see them planted in suburban landscapes. In today’s smaller lots, they are often plopped right in the middle of a lawn with a neat ring of mulch around them. Having mowed a lawn or two, I can’t help but think about how difficult that is to mow around.

This tree ring could be connected to the bed behind it
Some people put several of these in their lawn, each one with a dedicated circle of mulch. Each circular object probably adds 3-4 minutes to the mowing job, making it even more of a chore.

These mini islands of arboriculture are more than just a pain in the neck, they are downright unnatural and not healthy for the trees.

What a chore!

How unnecessary to separate these!

In nature, trees are arranged in groups with natural leaf litter covering the ground around them. The deep and wide expanse of that leaf litter allows surface roots to be protected and fosters a healthy population of the bugs, worms and fungi that support the tree. Those bugs, worms and fungi help break down those leaves, releasing nutrients at root level for the tree.

Special types of fungi, called mycorrhizal fungi, forge relationships with the rootlets of the tree, helping to bring even more nutrients and moisture to the tree. The fungi benefit from the relationship as well, and this win-win arrangement contributes to your tree being healthy and happy.

You might think that the mulch ring around your tree performs a similar role, but tree roots extend farther than you think. Arranging trees in a group brings not only a more natural look but also benefits to the soil with more root cover.

Here a single large bed handles trees and shrubs

A simple path is all that is needed for access to the back

There are several other benefits to connecting your tree dots. Standalone tree circles chop up what might already be a small yard, emphasizing even more how small the area is. Joining smaller beds together creates a smoother look and using wide curves evokes a more natural landscape. Mowing chores will be easier and take less time.

An example of trees in a large, joined bed

A more natural look puts trees in a group

An alternative to grass paths 
With wider beds and less grass, you can incorporate more interesting plants like perennials or annuals.

For shady areas, use native ferns. For sunny areas, pollinator-powerhouses like perennial sunflowers, coneflowers and black-eyed Susans will contribute more to the local pollinators than the lawn ever would.

When you're ready to support more of nature, connect the dots in your landscape. I think you'll find it to be a win-win solution.

Sunday, March 1, 2015

A Perfect Plant for Birds in Georgia

Finding the perfect plant for gardeners who want to support birds would be a wonderful thing. Every bird lover would rush to purchase such a plant. Time to be amazed: such a plant exists and is native throughout Georgia. The plant is black cherry (Prunus serotina) - pronounced PROO-nus sair-OTT-ih-nuh - and it is found from far northern Georgia to the very southernmost counties. From east to west and north to south, black cherry thrives in the varied soils and climate of Georgia.

Black cherry (Prunus serotina) in bloom

Knowing what birds eat is the key to understanding why this plant, and its close native relatives, is such an ideal plant. Here is a quick review of the diet of adult birds. Adult birds, you see, are rather specific eaters.

Female red-bellied woodpecker on suet
Those adults that eat seed will flock to your seed feeders: cardinals, goldfinches, pine siskins, sparrows and finches of all kinds. You’ll also get birds like mourning doves, titmice, chickadees, bluejays and the occasional woodpecker. If you have some suet feeders, especially in winter, then you’ll bring in birds like warblers, wrens, bluebirds, and more woodpeckers that need some high energy food. Cold temps and snow cover will encourage even more species to stop by for a winter bite.

The plump fruits of black cherry 

In the spring and summer, birds focus more on their traditional adult diet and that’s where black cherry really shines. Birds that are frugivores (fruit is a large part of their diet) thrive on the small fruits of the native cherry trees, and as many as 53 different species of birds have been observed eating them (not all of them frugivores). These include birds like cedar waxwings, mockingbirds, catbirds and tanagers. Other wildlife eat the fruit too.

While adult diet is very important, we need also consider the diet of baby birds. That’s where the foliage of black cherry is important. A large percent of baby birds are raised on insects – 96% of bird species feed insects to their chicks. It takes an enormous amount of insects to feed just one clutch: an estimated 6000 to 9000 insects for a nest of chickadees and those are small birds.

Caterpillar of Furcula borealis on black cherry
While some of those insects are spiders and other things, most of them are caterpillars. Birds find caterpillars on the leaves of plants, primarily native plants. As most of you know, caterpillars are the larval form of butterflies and moths. Our native butterflies and moths have host plant relationships (think monarch butterfly and milkweed) with the plants they evolved with. Watch an entomologist explain it better in this short video.

Black cherry happens to be a host plant for over 450 different species of butterflies and moths. Species include those as familiar and beautiful as the Red-spotted Purple, the Viceroy, the American Lady, the Cecropia silkmoth, the Coral Hairstreak, and our state butterfly, the Eastern Tiger Swallowtail.

Of course there are still many more species, some of them drab colored moths (see White Furcula moth pictured) that we don’t notice. These make up the bulk of the caterpillar population that feeds these birds; they are most of the 6000-9000 insects that are needed to raise just one set of baby birds.

The yellow-rumped warbler eats insects in the spring and summer
You'll also be supporting the many adult birds that rely on an insect diet. Birds that are insectivores include the warblers, flycatchers like the Eastern phoebe, bluebirds, wrens, robins and our state bird, the brown thrasher.

The flowers of black cherry are numerous and attract a wide variety of pollinating insects, especially native bees of several types. If you like to support native bees, you now have another reason to want black cherry in your landscape.

All in all, black cherry has extremely high wildlife value. If you only want to have it for the birds, that reason is plenty is good enough. All the other critters will enjoy the fringe benefits.