There comes a point in every gardener‘s development when certain, seemingly inconsequential co-incidents begin to reveal themselves as the very deliberate patterns that they are. It’s a slow process, but eventually all the disjointed observations made both directly in the garden and indirectly through text begin to weave together, and things that seemed unrelated suddenly, well, relate. Take for example the two vines Campsis radicans and Lonicera sempervirens. While unrelated, both attract hummingbirds with their crimson, trumpet shaped flowers, and (a seemingly unrelated characteristic) both are prone to aphid infestations.... often with accompanying ant shepherds. While making assumptive jumps in logic often bite me in the butt down the road, I think it would be safe to say that these small critters act as an additional incentive to the hummingbirds (who are also small insect feeders). If I had to guess I would say whatever price the plants pays in loss of vigor, pays off in a greater likelihood of pollination.
Aphids on Campsis radicans and Lonicera sempervirens
To get back to my intended point, the more plants I get to know, there’s been a few larger global pattern that have stood out to me not only because of their scale, but mainly because I can't seem to make all the pieces fit together. The one that bugs me the most is the occurrence of closely related species on the eastern coast of Asia, and North America, but nowhere in between (most of the time). Additionally, while I know there are plenty of exceptions that could prove the contrary, the pacific coast Asian temperate plants often have flowers that are larger, more colorful, and just generally more showy then their North American counterparts. The pictures below will speak for themselves.
LEFT: Hydrastis canadensis - Goldenseal (North America)
Zone: 4-8
Purchase from: Amanda's Garden, Companion Plants, Everwilde Farms, Lazy S'S Farm, Prairie Moon Nursery
RIGHT: Glaucidium palmatum - Japanese Wood Poppy (Asia)
Zone: 5-7 (sources are over the place with this one, but given its native range this seems to be the most logical)
Purchase from: Plant World Seeds
LEFT: Symplocarpus foetidus - Skunk Cabbage (North America)
Zone: 3-7
Purchase from: Amanda's Garden, Lazy S'S Farm
RIGHT: Lysichiton camtschatcensis - White Skunk Cabbage (Asia)
Zone: 6-? (not much info out there on this guy)
Purchase from: Rareplants.eu (Could only find a European source for this)
Also check out the landscape this guy is native to... STUNNING!!!
LEFT: Anemone virginiana - Tall Thimbleweed (North America)
Zone: 3-9
Purchase from: Amanda's Garden, Everwilde Farms, Naturally Native Nursery, Niche Gardens, Prairie Moon Nursery, Shooting Star Nursery
RIGHT: Anemone hupehensis - Japanese Anemone (Asia)
Zone: 5-9
Purchase from: Cultivars and Hybrids widely available, Straight species more difficult to come by. Closest to straight species I could find was at Special Plants Nursery
LEFT: Arisaema triphyllum - Jack-In-The-Pulpit, (North America)
Zone: 3-9
Purchase from: Amanda's Garden, American Meadows, Companion Plants, Everwilde Farms, Forest Farm, Lazy S'S Farm, Forest Farm, Naturally Native Nursery, Niche Gardens, Prairie Nursery, Prarie Moon Nursery,Rare Exotic Seeds, Romence Gardens, Shooting Star Nursery, Toadshade Wildflower Farm
RIGHT, TOP: Arisaema candidissimum - Pink Flowered Cobra Lily (Asia)
Zone: 6a-9b
Purchase from: Plant Delights Nursery, Hillside Nursery, Broken Arrow Nursery, Brent and Becky's Bulbs, Digging Dog Nursery, Check out more availability here: Plant Lust
RIGHT, BOTTOM: Arisaema sikokianum - Snow Rice-cake Plant (Asia)
Zone: 5a-9b
Purchase from: Plant Delights Nursery, White Flower Farm, Sunlight Gardens, Lazy S'S
Farm Nursery, Check out more availability here: Plant Lust
LEFT: Dicentra eximia - Fringed Bleeding Heart (North America)
Zone: 3-8
Purchase from: American Meadows, Lazy S'S Farm, Plant Delights Nursery, Lazy S'S Farm, Niche Gardens, Outsidepride.com, Romence Gardens, Shooting Star Nursery
RIGHT: Dicentra (Lamprocapnos) spectabilis - Showy Bleeding Heart (Asia)
Zone: 2-8
Purchase from: Deer-Resistant Landscape Nursery, Lazy S'S Farm, New Garden Plants, Rare Exotic Seeds, Romence Gardens, Sooner Plant Farm, Willow Creek Gardens
LEFT: Hamamelis virginiana - Common Witch Hazel (North America)
Zone: 3b-8
Purchase from: Amanda's Garden, New England Wetland Plants, Nasami Farm, Cold Stream Farm, Forest Farm, Lazy S'S Farm, Greenwood Nursery, Plant and Gnome, Prairie Nursery, Shooting Star Nursery, White Oak Nursery
RIGHT: Hamamelis mollis - Chinese Witch Hazel (Asia)
Zone: 5-8
Purchase from: Many cultivars and parent to many hybrids, but difficult to find straight species. The only 2 sources I could find were both European, Crocus, Burncoose Nurseries
LEFT: Jeffersonia diphylla - Twinleaf (North America)
Zone: 4-9
Purchase from: Amanda's Garden, Companion Plants, Everwilde Farms, Gardens in the Wood of Grassy Creek, Lazy S'S Farm, Nasami Farm, Prairie Moon Nursery
RIGHT: Jeffersonia dubia - Asian Twinleaf (Asia)
Zone: 4-7
Purchase from: Plant Delights Nursery, Hillside Nursery, Keeping It Green Nursery, Lazy S'S Farm
LEFT: Nelumbo lutea - American Lotus (North America)
Zone: 4-10
Purchase from: Everwilde Farms, Flora Exotica, Rare Exotic Seeds, Horizon Herbs
RIGHT: Nelumbo nucifera - Sacred Lotus (Asia)
Zone: 4-10
Purchase from: Flora Exotica, J.L. Hudson, Rare Exotic Seeds
Don’t get me wrong, I love our natives. And I think our “American equivalents” with their simple beauty are somehow more self-possessed than their ostentatious Asian cousins. On the other hand, there is no arguing that the Asian species seem to have been tailor-made for the more obvious beauty of the garden. But when you zoom out a bit contextually, ignoring the superficial aesthetic differences between the two groups, and start to look at things more broadly in terms of our earth’s natural history, certain questions start to arise that aren’t easily answered. And while I’m sure there is some evolutionary biologist or botanist out there that has long ago looked into these things, I have yet to find the answers for myself.
I suppose it’s easiest to start with the facts, or at least the facts as we currently understand them. While vascular plants have been around for a bit (approximately 400 million years) flowering plants, and flowers as we know them came on the scene fairly recently (between 130-125 million years ago) somewhere in present day eastern China. While no actual fossils have been found, it’s believed that the first blossoms would have very closely resembled those of the magnolia family (Magnaoliacea). I can’t help but think if would have looked an awful lot like the flowers of 2 of our native trees: Tulip Tree (Liriodendron tulipifera) and Cucumber Magnolia (Magnolia acuminata), with petals that aren’t too far removed visually from their leafy ancestry (mostly green with only a few streaks of color at the base of the petals to attract insects).
Flowers of Liriodendron tulipifera and Magnolia acuminata
If we look at this evolutionary history in the context of geologic time, specifically Pangea, the former supercontinent, obvious questions begin to arise regarding these plants current distribution. To start with Pangea began breaking apart approximately 200 million years ago, well before the first flowering plants appeared, and by the time they started to diversify at least 70 million years later (a VERY rough estimate), whatever land that might have connected the two continents would have been long gone.
Red areas of eastern Asia and North America indicate the general area where closely related plants can be found on either continent. In addition to those shown above this list includes species in the genus Asarum, Castanea, Catalpa, Chionanthus, Cornus, Diospyros, Disporum, Hepatica, Iris, Lilium, Malus, Polygonatum, Thalictrum, Viola,... and the list goes on.
So assuming all these things to be true, how then did we end up with closely related flowering plants thousands of miles away from each other on two different continents separated by deserts, mountains, tundra, and oceans? Add to this the complexity of multiple ice ages (advancing and retreating glaciers) and the picture only becomes more complex.
TOP: Showing the frequency and number of ice during the past 450,000 years
BOTTOM: Maximum extent of continental ice sheets during the zenith of the last ice age
Aside from the general similarities of relative continental and latitudal location, there is no clear singular answer to the question of how these plants reached their current distribution (or at least none I can find). On the other hand at least the aesthetic differences between the two groups does have (at least seemingly) a fairly logical explanation. Nearly all of northeastern North America, at least during the last ice age, was beneath the Laurentide ice sheet, so a great deal of the genetic diversity of plant populations of this area would have been lost with the advance of the ice, and gradually repopulated by plants to the south once the glaciers began to retreat, approximately 20,000 years ago. Northeast Asia on the other hand remained largely untouched by advancing glaciers, leaving the genetic diversity of these areas intact. This, coupled with the drastic changes in topography and resulting diversity of microclimates of eastern Asia allowed for much more advanced speciation that simply wasn’t possible in northeastern North America.
So the next time you have Asian plant envy just remember that these plants have had tens of thousands if not millions of years more to continue to evolve and diversify in situ, time that the plants of northeast North America simply haven’t had. What people also fail to realize, or conveniently forget is that evolving alongside these Asian beauties was an equally diverse number of foreign disease causing invertebrates, microbes, and viruses. Pests and diseases that their closely related North American equivalents have not had the luxury of spending millions of years evolving defenses for, which, not so surprisingly, often leaves the North American plants vulnerable and defenseless against such pathogens when they are introduced to the Americas. So when these Asian cousins are brought over, at some point, an individual will carry with it a hidden disease or pathogen that has the potential to, if not literally, at least functionally wipe out an entire species (a “great” example of this would be chestnut blight, caused by Cryphonectria parasitica that decimated Castanea dentata aka American Chestnut).
So rather than seek these foreign plants out do your best to appreciate the simple elegance of our natives, and explore the beauty of eastern Asian plant diversity through pictures only. But, if you can't help but give into temptation try to grow these Asian species from seed first, as seeds alone are much less likely to carry disease than entire plants (or at the very least, know where your plant material is coming from and be vigilant when you plant these exotics in your garden!).
