Wednesday, August 12, 2009

Confessions of a Gesneri-nerd

Above is Hemiboea subcapitata, among the hardiest of gesneriads for me so far, having overwintered successfully even in large containers. Its one aesthetic drawback is that the bracts which subtend the tubular blooms invariably turn brown just as the flowers begin to open. Below, Kohleria 'Longwood', tender, but happily bedded out for the summer.A person whom I used to consider one of my best friends has been riding me unmercifully about having attended the annual convention of the National Gesneriad Association in Silver Spring, Maryland last month. Try as I might, I’ve been unable to disabuse him of the notion that this constituted either (a) a coven of old ladies sporting red hats and purple dresses swooning over African Violets (not that there's anything wrong with that) or (b) a gathering of nerds in skin-tight spandex huddled in groups discussing favorite episodes in which various Gesneriads attacked the Starship Enterprise (that either...I guess). In truth, it was sort of both, featuring a spectacular array of plants for sale and on display, lots of nice, knowledgeable people, and what I’m sure were very informative lectures which I would love to have heard, had time and circumstances permitted.

So when our friend arrived the other night, I was prepared: I had many new plants to show him that I considered indicative of what was available at the sale, but nowhere else; several examples of blooming gesneriads in the landscape which are totally hardy here; and, best of all, a brand new, very flamboyant (they had a more tasteful version, but I figured I’d let my gesneriad freak flag fly all the way) new t-shirt. It’s emblazoned with a colorful botanical illustration of Episcia reptans, about a thousand times normal size, and a banner headline that reads “The Gesneriad Society.” Sadly, my friend (as well as my long-suffering partner) remained unimpressed. Pressing on, I regaled them with the virtues of gesneriads as hardy landscape plants here, mentioning that I've been trialing some plants for hardiness which had heretofore been considered only suitable for greenhouse cultivation. I showed him one of my tiniest Sinningias (‘Rio das Pedras’), full grown and comfortable in a pot the size of a thimble; his comment was “I bet people walk all over those in South America all the time and never notice.” Finally, just to humor me (he does this, which is one reason I like him so much), he did ask an extremely intelligent question: “So just what makes a plant a Gesneriad?”.

If he had asked the same question about a Begonia, I’d have been ready. Ditto for lots of other botanical families. However, the only response I could make to this question was to stammer and stare; I was totally stumped. It’s just an incredibly diverse tribe, and there are genera (Rehmannia, for example) about which even botanists can’t seem to agree in terms of whether they’re Gesneriads or members of the Scrophulariaceae. On top of this, the scientific names change back and forth on what seems like a weekly basis. Since I was finally speechless on the subject, I poured him another vodka-watermelon smoothie and let my friend take over the conversation, which is usually the best plan when he’s around, anyway. He’s darned entertaining, even if he does do a pretty good impression of a botanical cretin.

After researching his question, I feel somewhat vindicated. Every definition of the family Gesneriaceae that I can find is riddled with inconsistencies – the words “most” and “many” are commonly used. There seem to be very few uniquely defining factors, as in this Wikipedia article:

"Most species are perennial herbs or subshrubs but a few are woody shrubs or small trees. The phyllotaxy is usually opposite and decussate, but leaves have a spiral or alternate arrangement in some groups. As with other members of the Lamiales the flowers have a (usually) zygomorphic corolla whose petals are fused into a tube and there is no one character that separates a gesneriad from any other member of Lamiales. Gesneriads differ from related families of the Lamiales in having an unusual inflorescence structure, the "pair-flowered cyme", but some gesneriads lack this characteristic, and some other Lamiales (Calceolariaceae and some Scrophulariaceae) share it. The ovary can be superior, half-inferior or fully inferior, and the fruit a dry or fleshy capsule or a berry. The seeds are always small and numerous. Gesneriaceae have traditionally been separated from Scrophulariaceae by having a unilocular rather than bilocular ovary, with parietal rather than axile placentation."

While this question may continue to be perplexing, at this time of year I’m very appreciative of the contribution that the members of this very diverse family make to the garden. Many species and hybrids are proving to overwinter as perennials here in Southeastern VA, zone 7b, and numerous others are perfectly adapted to dry storage as rhizomes and tubers, making them perfect for summer container culture.

Below are the windowboxes from my last post, shown again here to illustrate some of the ways gerneriads can contribute to the summer garden. The scandent Begonia is B. boliviensis, but the darker, more upright foliage belongs to Kohleria 'Dark Velvet'. Kohlerias are rhizomatus gesneriads, but their dormancy is unpredictable, so they don't lend themselves to prolonged winter storage as do Achimenes, Sinningias, and Eucodonias, for instance. They're also extremely tender, browning off at temps in the 40's. Luckily this variety is easy to root from cuttings and grows like a weed all summer, adding its tall, felted, chocolatey foliage to containers in shade to part sun.
Here's a detail of the tubular, speckled blooms of K. 'Dark Velvet'.
Another view of the windowboxes and surrounding bed, showing more gesneriads on the lower level - Achimenes 'Purple King' and Gloxinia nematanthodes 'Evita'. These two are now ubiquitous in the garden, apparently hardy even in pots and containers left outside over the winter. Can't help but notice the "color echo" among the Begonias, the Gloxinia, and and the Arisaema seedpod in the forground.
Titanotrichum oldhamii was the first of the hardy gesneriads I planted outside, and it's been fairly dependable, especially given some supplemental summer irrigation. It's like a tall, shade loving foxglove that puts up spikes of yellow bells every fall - it's a good illustration of the close connection between the gesneriads and the scrophulacea. Interestingly, instead of flowers, less mature plants produce terminal wands of beady propagules, which can be "sown" just like seeds to produce hundreds of new plants.
Tremacron aurantiacum, another Chinese gesneriad, and the only rosette-forming representative of the family with which I've had much success in the outdoor garden. Ramondas have been a dismal failure, melting away during the hottest part of the summer; I do have two Haberleas growing fairly well in raised beds, but they haven't bloomed so far. Tremacron is an extremely obscure genus, and there's almost no literature available on it; the closest affiliated genus I've been able to discover is Briggsia, and barely more has been written about it. Trial and error is the only way to go in a case like this. For this week, at least, the two plants below are included in the genus Seemannia; they were Gloxinias before, which is not the same as the genus including the familiar florist's Gloxinias, which are actually Sinningias. Clear as mud? The first illustration in Seemannia sylvatica, which produces lush growth all summer long, but waits until November to bloom, being sensitive to day length. It does behave as a herbaceous perennial here, but there's not much point in growing it outside, since our first frosts prevent its flowering. I do think it would have great potential as a holiday house plant; it's certainly much easier to rebloom than a poinsettia or a Thanksgiving/Christmas cactus.
Seemannia nematanthodes 'Evita' is perfectly hardy here, where it, along with Achimenes 'Purple King', has insinuated itself into beds and containers all over the yard, mostly due to my recycling potting soil in which are hidden the chubby white rhizomes which serve to carry the plant through the cold months if kept barely moist. It has even wintered over successfully in pots and containers left standing outside without protection.
As mentioned before, the florist Gloxinias are simply a group of Sinningias hybridized from a peloric (which means that the individual blooms exhibit a radial symmetry atypical to those of the normal species- I think) form of S. speciosa, pictured below. Grown from seeds several years ago, these seem to manage fine planted all year in the dry shade beneath an overgrown Magnolia grandiflora (everybody has at least one of those in these parts.) Sinningia guttata, also hardy in a raised bed, and another parent of the florist's Gloxinia. I should mention that I have wintered over tubers of those hybrids outdoors as well. If anyone knows of a reputable source for "Emperor Frederick", a once-common old cultivar that's a sentimental favorite (my grandmother gave me one for my birthday once), I'd love to grow that again.
Sinningia tubiflora is bone hardy all over the garden and in containers, and is a dead ringer for Nicotiana alata when it blooms in June in the dry partial shade under the skirts of a Magnolia grandiflora which needs to be removed on day. It's as easy to grow as potatoes, and can be stored in a similar manner through the winter if hardiness is an issue. Here's another visit with the companion planting of Eucomis 'Sparkling Burgundy' with Sinningia selloviae, another dependably hardy gesneriad that's a real workhorse in my summer garden. I've tried unsuccessfully to grow Phygelius for years, but I've found that this plant and its hybrids give a similar effect (vertical spires of tubular flowers in reds, oranges, and creamy yellows) but are much easier to grow here. Some of the tubers (grown from seed) are the size of baseballs now. I have a couple of plants of S. selloviae 'Purple Rain', but that selection seems to be a much weaker grower for me thus far.
The white form of Sinningia cardinalis ('Innocence'), leaning out from under a containerized Hellebore. It would probably like more sun, as most of the Sinningias seem happiest in strong light. Haven't tried this yet for hardiness, but I have enough to do so this year, and have high hopes.
I think this is Sinningia lineata; it's pretty tough, and quite possibly hardy here, as well. It's one of the determinate growers, unlike selloviae, tubiflora, and their hybrids (Sinningias can be determinate or indeterminate bloomers and growers, just like tomatoes). This, in my opinion, limits its potential as a garden plant - it doesn't mean I won't grow and enjoy it, but the finite bloom period makes its impact more fleeting in the landscape. The miniatures and semi-miniatures fall into this category as well, and have demonstrated pretty good winter hardiness, provided the tubers are kept dry. Their main drawback is their size - one fallen leaf can obscure an entire plant for long enough that I completely forget it's there until it's too late. For now, they live in the garage under banks of fluorescent lights (which thankfully are back in operation after having had to be dismantled for a construction project.)
Sinningia conspicua is hardy here, and enjoys as much sun as possible. I first saw this species growing in the high desert garden at the NC State Arboretum, which was an "aha" moment for me regarding the cultivation of this genus in general.
Sinningia 'Butter and Cream', another of the selloviae-tubiflora complex of hybrids which propagates easily by tip cuttings and returns annually. This one is a nice substitute for Phygelius 'Moonraker', with which I've struggled ever since seeing great swaths of it in St. James Park in 1996. This ain't London... in lots of ways!
A newer acquisition, Primulina tabacum, a rosette-forming gesneriad which seems to do well in the shady plunge bed. It hasn't spent a winter outside yet, so the jury's still out. It may be more interesting than beautiful, but so are a lot of the things I grow (and many are only interesting to me...I live in fear of the crew from "Curb Appeal" on HGTV showing up at our house!)
Below are several more pics of Seemannia nematanthodes 'Evita', which is just coming into full bloom right now all over the garden. It's great for filling in late summer gaps everywhere, and blends well with many other things, including tomatoes!
This clump should look great when it blooms in a week or two, especially if the Rudbeckias hold out long enough to offer some contrast in shape and color.

Not hardy (as far as I know - trying it this year), but cool, is what used to be called Koellikeria erinoides; I think it's actually a Gloxinia these days. I have lots of them, due to its propensity for reseeding itself and ability to be propagated by dividing the long, scaly rhizomes, which are easy to store dry in pots over the winter. Here it's a great foil to the dwarf Eucomis vandermerwei; the whole pot goes into my parents' shed in October, and I don't see it again until April, when I bring it out, water it, and begin the cycle again. I may have mentioned this before, but the rhizomatous gesneriads and South African bulbs seem to have very similar cultural needs, and make great companion plants, also being complimentary in foliage and bloom. It's a hard plant to photograph well outside, and there are much better pics of it on the Gesneriad society site. One of my secret (not anymore...), guilty, Martha Stewart-esque "good things" is to use Ron's collection of McCoy Rustic pottery as caches for pots of these when they come into bloom - the creams, greens, and browns of the pottery and the plant are perfectly in sync.
This container is treated in the same way as the previous one. It combines Kaempferia roscoeana, one of the monsoonal, shade-loving gingers, with Eucodonia andrewsii, another of the smaller rhizomatous gesneriads which has spread itself throughout our planting beds. The flowers, when they begin, are small, slipper-shaped, and an exact color match with the flowers of the Kaempferia.
Another E. andrewsii produced from the same pinch of seed -
the foliage of this species seems to come in two color phases. It tends to begin blooming in late August- early September, along with its relatives, the Achimenes. A Chirita ('Chastity'?) which was a gift from some great gardening friends, tucked in among the roots of the Magnolia. It wintered over last year, but I keep another in the greenhouse for insurance. I have a couple of other hybrids that I plan to try outside eventually as well. These don't really have well-developed underground storage structures or rhizomes, so I suspect their hardiness may be less dependable by far than those gesneriads that do.
The Achimenes are just beginning to bloom now, and they're becoming some of my favorite plants. The small, purplish rhizomes are ridiculously easy to store over the winter in small bags of vermiculite, and some, which are inevitably left behind in the ground or in containers over the winter, return every summer throughout the garden. About the only drawback to growing them is the fact that they respond to drought by going dormant, so consistent moisture (without overwatering, the eternal paradox of gardening) is necessary. Below is 'Harry Williams'.
This is A. 'Yellow Queen'.
And A. 'Purple King', which is becoming a great "passalong plant" throughout the south, and with good reason - I grow it everywhere. It's the earliest blooming variety, produces a myriad of rhizomes which can be stored or left in the ground over winter (and even in pots, apparently.) Here it's spilling over the top of one of our rain barrels, weaving in among the Trachelospermum which constantly threatens to engulf the house.
There are so many other gesneriads waiting in the wings (and the greenhouse...and the light garden in the garage...) for garden space, that I suppose I do have good reason to be embarrassed about it. We all have our little (?) manifestations of sublimation and denial in life, and the insatiable acquisition and propagation of plants appears to be one of mine. At the aforementioned convention, I found lots of new plants to try in the garden, and a few that will never go outside - why I need to grow Episicias or Gesneria cuneifolia, which basically require life-support, is another question, but they are here, too, along with Niphaeas, Diastemas, Lysionotus, Vanhoutteas, and many others too numerous to mention. One day, when they're finally rid of me and all of my craziness, I hope my partner and friends will invite some real plant nuts over to clean the place out!

One more Chirita for the road...