Over a decade ago I decided to try planting the native Frogfruit (Phyla nodiflora) in the maritime grassland exhibit at the South Carolina Botanical Garden. To my amazement, this species that I knew of from the fringes of saltmarsh in the Lowcountry thrived in both wet and dry soils of the upper Piedmont of South Carolina! The plant has proven to have incredible versatility and grows well in sand or clay and can be flooded for weeks and completely dry as well. Unlike many other plants that can accommodate such diverse conditions it isn’t so ugly that only a mother could love it, in fact, it’s charming.
Frogfruit is a low (4” tall) trailing groundcover with 1.25” long leaves that forms a solid mass of foliage but lacks deep root structures and thus does not compete with deeper rooted structural element plants. The flowers are pale pink to lavender and resemble tiny lantanas (a close relative). The flowering season here in the south begins in April and can continue through hard freezes (typically November) but may produce flowers year-round in mild winters.
Phyla nodiflora ‘Ramble On’
Our plants, Phyla nodiflora ‘Ramble On,’ are from a Charleston County, South Carolina collection along the margins of a wet ditch (freshwater), but the species has an amazingly wide range being found from New Jersey west to California and throughout the tropical regions of the world. Another species, Phyla lanceolata, is a more upright plant, with a similar range (but extending north to Ontario) it has longer leaves and is generally less showy as a groundcover.
Phyla nodiflora ‘Ramble On’
This is the ideal living mulch for tough areas of your landscape. It spreads rapidly but is easy to keep contained by trimming the edges of your patch. We placed it in one of our pond overflow pits and were amazed to see it completely transform a time-sink of constant weeding into a mass of lovely little flowers while allowing the Hymenocallis and Hibiscus to continue to rise through the groundcover without obstruction.
The flowers are favored by skipper butterflies, particularly the smaller species and there is an all-day-long collection of hundreds on our patch every day. In addition, small flies, native bees, sweat bees and tiny wasps are fond of their constantly produced flowers. The leaf and stem color ranges from green to deep purple depending on the environmental conditions—generally, the more exposed to sun, intermittent drought or salty soils, the more purple in the plant. If the goal of your garden is to increase the production of life by filling all your spaces with plants that are loved by insects while at the same time reducing the need for mulch and weeding, this plant is definitely worth a try. Look for this in the near future. – Patrick McMillan.
Despite the impending flooding late last week, Patrick, Zac, and I took off to the mountains of western South Carolina for a few days of botanizing. Despite the monsoon-like rains, we managed to visit seven amazing sites. Below is a highlight.
One stop was at a giant granitic outcrop. The rocks are covered in an array of mosses, lichens, and other associated flora, most growing in shallow pockets or organic debris that alternation from inundated to bone dry for months.
Large patches are covered with the colorful, 1″ tall, annual sedum, Diamorpha smallii, commonly known as Elf orpine.
Diamorpha smallii
Another site also had large granite flatrocks, but with a complete different flora. Here, two dryland ferns, Cheilanthes lanosa and Cheilanthes tomentosa formed large patches, along with the amazing Selaginella tortipila.
The more shaded slopes were filled with amazing clones of the dwarf painted buckeye, Aesculus sylvatica, which at this site, mature at only 3-5′ in height. In most other area, the same species matures at 10-20′ tall. The flower colors here ranged from peachy yellow to screaming orange red.
Aesculus sylvatica dwarf forms
One of our next stops was an amazing watershed where, Shortia galacifolia grows by the acre, carpeting the mountain side. This is the world’s largest population of this amazing native. We even found it growing epiphytically on a rock, perched in the middle of a stream.
Shortia galacifoliaShortia galacifolia
The native Micranthes micranthidifolia grew along the moist stream banks. This is the first time I’ve seen this, since I first purchased the plant back in 1995 from the former We-Du Nursery. In that case, I killed it, before getting it planted.
Micranthes micranthidifolia
Another plant I’ve killed in my previous attempt was the native climbing fern, Lygodium palmatum. Here, it grew with the easy-to-grow Christmas fern, Polystichum acrostichoides.
Lygodium palmatum
The difficult to grow Asarum heterophyllum was scattered throughout our several mile trek, almost all plants were the solid green leaf form.
Asarum heterophyllum
Far easier to grow is the native Hydrangea radiata (formerly known as H. arborescens var. radiata), with its shimmering white-backed leaves.
Hydrangea radiata
As we walked along the towering cliffs, the red fruit adorning the carpets of partridge berry, Mitchella repens glistened in the rain.
Mitchella repens
Several patches of mayapple, Podophyllum peltatum had some of the largest foliage that I’d ever seen, measuring 1′ in width.
Podophyllum peltatum
Not far away we saw some of the most strikingly patterned form of Pachysandra procumbens we’ve ever seen.
Pachysandra procumbens
We almost got through the entire trip without finding a single variegated or colored foliage mutant, when not far from the parking area, we spotted a streak sport on Kalmia latifolia.
Kalmia latifolia streaked branch
Below is our incredible, but soaking wet, botanizing team (l-r) Adam Black, Bartlett Arboretum, Zac Hill, JLBG, Patrick McMillan, JLBG.
Great new plants for the garden do sometimes just happen. They can occur as a spontaneous sport from an existing planting, as a seed selection that has much better garden traits, but many of our most useful and ecologically important plants in the garden have their start in exploration. I was thinking about this today as I observed the tightly-clumping overwintering rosettes of one of our newest introductions to the JLBG—Oenothera riparia, Riverbank Sundrop.
Oenothera riparia
Sundrops hold a special place in my heart. My grandmother loved them and had large swathes of the old pass along yellow standard Oenothera fruticosa/tetragona in her extensive garden. Every June they would burst into flower for a brief week or so, bringing a brilliant light and foil to her many glorious iris. As I mature, I have come to value plants with connections to our being but also the value of similar plants that can provide the same nostalgia while giving us much more in the landscape.
A plant known as Riverbank sundrops may be a perfect example of a great garden plant that is native to the Southeast and provides more of what gardeners love, while also providing the native insects and other wildlife an abundant resource.
Oenothera riparia was described by Thomas Nuttall in 1818 from plants collected along the Cape Fear River near Wilmington, NC. Nuttall provided a very full description of the plant (for the time) though he presumed it to be a biennial—it is in fact a long-lived perennial. J.K. Small recognized the species in a segregate genus as Knieffia riparia in his 1903 Flora of the Southeastern US. In 1937, Munz reduced the species to varietal status as Oenothera tetragona ssp. glauca var. riparia, and after this it was essentially lost to the minds of taxonomists and plant enthusiasts being considered merely part of the immense variability of Oenothera fruticosa by Radford, Ahles and Bell (1968).
In the mid 1990’s while working in the tidal freshwater swamps and marshes of South Carolina, Richard Porcher and I encountered this species growing at the bases of Bald Cypress trees, on stumps, and on floating logs just above the high-water tidal line on the Waccamaw, Pee Dee, and Edisto Rivers. My frustration with its identification led me to the name Oenothera riparia and its recognition as a completely and consistently distinct taxon—which is very unusual in a genus known for its morphological variability and messy taxonomy.
Oenothera riparia
This plant is smooth (lacking hairs) throughout with thick textured dark-green leaves and a very bushy habit—it does not produce long stolons or rhizomes, so it forms a dense clump. The stems generally range from a foot to nearly 3 feet in height and the thick stems become semi-woody, providing a stiffly upright growth form. Rather than a single burst of flowers this species produces masses of flowers over the entire summer (June-late August) with sporadic flowering later in the season.
Imagine, here we could have a sundrop that won’t spread like wildfire, doesn’t flop, and flowers for month after month! Sounds like everything you would want in a plant. There is only one problem, it hasn’t been cultivated. This is where the adventure continues and as we embark on this adventure, I would like to take you along for the ride. There is so much that goes into identifying a potentially great garden plant, evaluating it, and bringing it to the trade.
Our initial collections were made this August (2022) when Zac Hill, my wife Waynna, and I were traveling through the SC coastal plain. We made the stop at the Edisto River in Colleton County where I had seen the plant many years before and just like I remembered, there they were, full of seed and with some flowers still present. The only problem is that they were growing far out in the water along the bases of trees! The Edisto is a blackwater river with a large tidal amplitude at this location and it was full on high tide. If you’re a field botanist you forget entirely about the things that concern other more rational folks, like the multitude of large Alligators, and make for the plants. I found some low branches on a neighboring willow tree that kept my feet in only a couple feet of water, and balancing on the branch, in the water, made my way all the way to the edge of the river where a fabulous floating log provided an abundance of seeds and two small plants from a large cluster of individuals. The only casualty was my prescription glasses which promptly fell from my head into the depths of a rapidly moving Edisto River (my wife will not easily let me forget the cost of this single collection). The first step in the process of bringing a new plant into production is done.
Oenothera riparia
Our two small divisions were placed directly into the sun garden at JLBG and the seed was sown. For this plant to be successful in a garden it must be able to not just survive but thrive in a common garden condition far away from its very narrow niche at the very upper edge of the water along the Edisto. You might think this would be unlikely, but other incredible garden plants are entirely found in wetland communities and thrive under very different conditions in the garden. A good example of this is found in another of our introductions, Eryngium ravenelii ‘Charleston Blues’, which comes from high pH wetlands not too far away from the Edisto River.
Will it be hardy here? Will it survive under normal garden conditions? Will it maintain its distinctive and garden-worthy features? Well at least part of this can be answered already. Our tiny divisions are now large overwintering basal rosettes. The plants have not thought about running away from their tight cluster, and they grew very well during their first autumn in soil that was not kept overly moist.
The real test lies ahead. What will the plants nature be under cultivation? Will it be as good as I think it could be? Will it be better? One can only hope, put in the labor, and follow along to find out the end of this story for Oenothera riparia. It could provide all of us with a stately and handsome bit of nostalgia with far greater design and utilitarian use for humans and our native biota. What’s more, there are other seemingly great garden-worthy Oenothera out there—not in far-flung locations but right here in the Carolinas. Have you ever heard of Oenothera tetragona var. fraseri? If not, look for us to tell you more about that in the years to come, there’s a fantastic form with huge flowers in the Blue Ridge escarpment of South Carolina!
You go straight through to the round of botanical superstars if you recognize this little-known southeast native (SC to Florida), Piriqueta caroliniana. This Patrick McMillan collection from coastal SC has thrived all summer in our full sun rock garden, flowering constantly, with new flowers opening every other day. This oddity is a member of the Turneraceae family, which comprises nine other equally obscure genera. We’ve yet to determine if this will actually make a good garden plant, but evaluation continues. Hardiness north of Zone 8a is unknown.
