Sunday, May 27, 2012

Out of the Ordinary Dogwoods

Those of us that grew up in the south are very familiar with the tree known as flowering dogwood (Cornus florida). The large white bloom is one of the iconic flowers of the southeastern United States. Many people don't realize that there are other shrubs and small trees in the same genus which are native to Georgia.  Other family members include alternate leaf dogwood (Cornus alternifolia), silky dogwood (Cornus amomum), toughleaf dogwood (Cornus asperifolia), swamp dogwood (Cornus foemina), and rough dogwood (Cornus drummondii).  In the northeastern areas of the U.S. there are even more native species of dogwood, many of which are commonly used in landscaping there.

Silky dogwood, Cornus amomum
The floral structure of the "other" dogwoods is quite different from that of flowering dogwood. Each inflorescence is composed of several dozen small flowers.

Each pollinated flower will turn into a small berry, often a round, blue-colored berry which is quite unlike the red fruits borne by Cornus florida.

Cornus amomum

Berries, Cornus amomum

By chance this week I passed a large group of silky dogwood on a rural roadside. It was loaded with flowers in various stages of bloom: some had faded and seeds were forming, while others were still in tight buds.  Obviously growing in ideal conditions (adequate moisture and full sun), it was a beautiful sight and pollinators were all over it. It was a very exciting find for me - I had never seen this species in flower before.  I plan to return in the late summer to see the berries.

Cornus amomum

The only other dogwood that I've successfully grown in my yard (so far!) is alternate leaf dogwood (Cornus alternifolia). The name is significant because other dogwoods have oppositely arranged leaves. Branches on this species are often elegantly arranged in tiers, earning it yet another common name: pagoda dogwood. The glossy foliage is very handsome. This species makes a fine small tree.

Cornus alternifolia
Look at this great foliage!

I hope to get more familiar with other species over time. Several of them are very wet tolerant - especially swamp dogwood, I have seen it growing in standing water. The birds love the berries of course and the flowers attract many small insects for birds to feed their chicks.  You should consider adding one of these other dogwoods to your garden.

Flowering dogwood, Cornus florida
By the way, the large flowers of Cornus florida are made up of four showy white bracts with a cluster of small flowers in the center. 

Sunday, May 20, 2012

Ferns That Work For You

Ferns are one of the true non-flowering plants.  These ancient plants reproduce by spores - an amazing difference that is worth explaining to your kids/grandkids. Spores are often found on the back of the frond (or leaf if you will); they are clustered into spore cases (sporangia) that are grouped in clusters called sori.  Fronds with sori are fertile fronds, and some ferns produce unique fertile fronds that look nothing like the other fronds.

Sori on Dryopteris marginalis
Fertile frond with sori on
Botrychium biternatum

Despite their lack of flowers they provide beauty and versatility in the garden and support wildlife in less noticeable but unique ways.  Songbirds use fronds from some of the more delicate ferns like New York fern (Thelypteris noveboracensis) for nesting material. Insects feed on some ferns while others provide cover for reptiles, amphibians and small mammals.

Georgia has a bunch of indigenous ferns, many of which are perfectly suitable for average garden use, especially in shade/part-shade conditions. The larger ferns offer bold green foliage to be used as a foil against other plants. Small ferns can serve as accent pieces, particularly in tight spaces or at the base of trees. Wet tolerant ferns provide a solution to a difficult area and running ferns fill up spaces that might otherwise be hard to reach.  I'd like to introduce you to the possibilities of using native ferns in Georgia.

Northern maidenhair (Adiantum pedatum)

Large ferns: size is subjective, of course, but these are the native ferns that in my garden grow fairly large: Christmas (Polystichum acrostichoides), sensitive (Onoclea sensibilis), southern shield/southern wood (Thelypteris kunthii), lady (Athyrium filix-femina), northern maidenhair (Adiantum pedatum), hay-scented (Dennstaedtia punctilobula), marginal wood (Dryopteris marginalis), cinnamon (Osmunda cinnamomea) and royal (Osmunda regalis).

Red-stemmed lady fern (Athyrium filix-femina)

Small ferns: petite little wonders to tuck into special spots: ebony spleenwort (Asplenium platyneuron), brittle fern (Cystopteris protrusa), grape (Botrychium spp.), and adder's tongue fern (Ophioglossum vulgatum).

Adder's tongue fern (Ophioglossum vulgatum) 
Photo by S. George

Ebony spleenwort (Asplenium platyneuron)

Running ferns: ferns that will send out rhizomes and increase in size by traveling: netted chain (Woodwardia areolata), New York (Thelypteris noveboracensis), sensitive (Onoclea sensibilis), broad beech (Phegopteris hexagonoptera), and Virginia chain fern (Woodwardia virginica).

New York fern (Thelypteris noveboracensis)
Broad beech fern (Phegopteris hexagonoptera)

Wet tolerant: ferns that don't mind being wet occasionally or always: cinnamon (Osmunda cinnamomea), royal (Osmunda regalis), sensitive (Onoclea sensibilis), and netted chain (Woodwardia areolata).

Cinnamon fern (Osmunda cinnamomea)

Sun tolerant: ferns that can take more sun, especially full-on morning sun, after 1 pm is a little tricky for any of them:  southern shield/southern wood (Thelypteris kunthii), and the very aggressive bracken fern (Pteridium aquilinum).  Both of these do run a bit and the more the moisture the more they run!

A robust clump of Thelypteris kunthii

Specimen: ferns that are especially attractive or unusual:  northern maidenhair (Adiantum pedatum) and southern maidenhair (Adiantum capillus-veneris), rockcap fern (Polypodium virginianum), resurrection fern (Pleopeltis polypodioides), and American climbing fern (Lygodium palmatum).

Rockcap fern growing on a log (Polypodium virginianum)

Evergreen ferns: ferns that retain some fronds year round in the metro Atlanta area: Christmas (Polystichum acrostichoides), marginal wood (Dryopteris marginalis), ebony spleenwort (Asplenium platyneuron), rockcap fern (Polypodium virginianum), resurrection fern (Pleopeltis polypodioides), and the fall-appearing grapefern (Botrychium biternatum).

A young Christmas fern (Polystichum acrostichoides)

If you're not using native ferns in your garden, give them a try.  They are a beautiful and useful addition to almost any condition.

Reference: Field Guide to the Ferns and Other Pteridophytes of Georgia by Lloyd Snyder and James Bruce

Sunday, May 13, 2012

A Walk in the Woods

Enjoying native plants is not just about using them in the garden for me.  It’s good to go out and see them in the places where they grow naturally, to take note of the communities in which they live, and to enjoy the beautiful arrangements that nature has created with them.  Last weekend the Georgia Botanical Society’s 42nd annual Wildflower Pilgrimage was in Clayton, GA, and I had a chance to go and enjoy some time in the woods.

Tradescantia subaspera - at home in the woods

Rabun County is one of the counties that borders North Carolina so we were in the mountains there.   Field trips included tours of waterfalls, rich mountain coves, creeks, gaps, ridges and all the neat places associated with mountainous areas.  But while each of them was lush with indigenous plants, it was disappointing to see how invasive plants have crept into even these places.  The worst one in general was multiflora rose (Rosa multiflora).  On roadsides it would cover huge areas, smothering native shrubs and small trees, shading out native perennials like Solomon’s seal (Polygonatum biflorum) and ferns that grew in abundance where the rose was not.  Inside the woods, small populations of the rose were forming in sunnier areas, poised to take over should a tree fall and the canopy open up enough for it to become the thug it wanted to be.

Enough doom and gloom – let me show you some of the special things we found.

Clintonia umbellulata - Clinton's lily

Geranium maculatum - was blooming heavily

Asclepias quadrifolia - fourleaf milkweed in the woods
Black raspberry was in abundance - Rubus occidentalis

Mountain laurel was in full bloom - Kalmia latifolia

Oxalis grandis - Look at the maroon edges

Polygonatum biflorum

Trillium vaseyi - the last of the trilliums
Pipevine - Aristolochia macrophylla

Umbrella leaf grew in a wet area of a rich cove - Diphylleia cymosa
I don’t always take the time to enjoy a trip just for looking. But whenever I do, I always wonder why I don’t do it more often.

By the way, if you’ve never read “A Walk in the Woods” by Bill Bryson, I highly recommend it. It is an amusing tale of one man’s determination to walk the Appalachian Trail and the adventures he has along the way.

Sunday, May 6, 2012

Late Spring Shrubs

Despite the recent hot weather, it is still officially spring in Georgia.  The heavy flush of early spring shrub blooms are gone now, but I noticed this week that round two has begun.  In my yard that is Virginia sweetspire (Itea virginica), mountain laurel (Kalmia latifolia), evergreen rhododendron (Rhododendron catawbiense) and oakleaf hydrangea (Hydrangea quercifolia).

Rhododendron catawbiense

Rhododendrons are typically higher elevation plants but I find they do well enough in North Georgia in north facing areas with good drainage.  I created a small berm in my yard and put a row of small ones that I got via mail order.  Three of them bloomed this year - 2 of them are the rosy-purple color so typical of the species Rhododendron catawbiense and one was billed as a white form but which ended up being a very pale pink.  Rhododendron in general is a large, open shrub and should be sited accordingly.  Be careful when researching cultivars if you are looking for native ones as many of them are hybrids with an Asian parent.

Loose and open habit of Rhododendron

Mountain laurel (Kalmia latifolia) is a similar shrub in that it is evergreen, large and becomes fairly open with enough age.  The two plants grow together in the mountains, creating massive groups of cool green along streams and mountainsides.  But in shady, well mulched areas, they also do very well in suburban gardens.  I bermed up (yes, I'm using that as a verb) an area near the house and planted them as foundation shrubs.  They get sun until about noon and just love it there.  Many, many cultivars are available in a range of sizes and colors.

Kalmia latifolia
Kalmia latifolia pink cultivar
Virginia sweetspire (Itea virginica) is a beautiful and adaptable shrub that looks good for 3 out of 4 seasons.  Handsome foliage is covered in long white spires in May, and each spire is composed of dozens of star-shaped flowers.  The foliage is attractive all summer and then changes to a deep burgundy come autumn.  If you get a cultivar like 'Henry's Garnet' or 'Merlot', the color is especially nice.  This shrub naturally grows along streambanks so it can handle overly moist soil, but it also does very well in average moisture.  My plants get no supplemental water at all.

Itea virginica
Itea virginica
Oakleaf hydrangea (Hydrangea quercifolia) is another year round good-looking shrub and should be used more often.  Those foreign blue mophead hydrangeas have nothing on this one!  With large, oakleaf-shaped leaves, the foliage on this plant is a winner by itself - especially when it turns purple in the fall.  The panicles of white flowers are very showy and continue to look good into the late summer as they fade to a pale pink, giving the appearance of persistent flowers. The panicles contain both fertile and non-fertile flowers, supporting pollinators in a way that the blue and pink ones don't.  The exfoliating bark in the winter is also very attractive.  Cultivars are available in double flowering forms, dwarf forms and even a form with golden foliage.

Hydrangea quercifolia
Hydrangea quercifolia 'Little Honey'

So if you're looking for some shrubs to extend your spring season, these are a few to consider.