Like many other plant characteristics, fragrance varies from individual to individual within a species, and this variability is genetic. This variation is most apparent when selfing newly collected species; these individuals still retain some of the natural heterozygosity which is eventually lost through several generations of self-pollination in cultivation. This is significant because wild-collected individuals will have the most potential for selecting for fragrance as well as for other characteristics. It is also significant because fragrance is a trait that can be selectively bred by plant hybridizers.
In the list that follows, some will find plants they do not consider fragrant, or unpleasantly so. Smell is perhaps our most subjective sense; people differ in how well they can smell particular fragrances, and in their reaction to those fragrances. For example, many people enjoy the scent of Sinningia conspicua and describe it as "lemony". I can barely smell this species, and what I do smell I do not consider especially pleasant, much less lemony. On the other hand, some fragrances that I enjoy, like that of Nematanthus Santa Teresa, others find offensive. Because of this subjectivity, it is very difficult to accurately describe fragrances. The intensity of a scent may also vary with time of day, or if plants are growing in an enclosed space. The accompanying descriptions are from my own observations, as well as those of many others. I am greatly indebted to the members of the Gesneriphiles Internet discussion list for much of the information that follows. Many thanks for additions to the list, comments on fragrances, and much stimulating discussion.
Oddly enough, there are very few members of the Old World subfamily (Cyrtandroideae) on the list, although this subfamily is largely pollinated by insects and should have many fragrant species. It may be that as more Old World species are brought into cultivation and are more widely grown, they will be discovered to be fragrant. In fact, the botanical literature describes certain species of Didymocarpus and Cyrtandra as having sweetly fragrant flowers, but none of these fragrant species are in cultivation. In addition, the New World species Anetanthus gracilis, Besleria insolita, and Drymonia lanceolata have been described on herbarium specimen labels as having sweetly fragrant flowers, but are not known to be in cultivation.
Achimenes has several fragrant species. Achimenes dulcis has very pretty pure white flowers that are midway between a slipper and a trumpet, not flat-faced like most of the more familiar species and cultivars. I first saw A. dulcis blooming in the Smithsonian greenhouses and thought it an attractive plant, but only later got to wondering why it was named "dulcis", meaning "sweet." The original description gave no explanation of the name. When I saw it blooming again in the greenhouses, I stuck my nose in, and sure enough, it had a pleasant sweet scent. Achimenes dulcis is a small plant (although tending to trail) with good-sized flowers, and could easily be grown under lights. It would be worth checking its close relative, A. mexicana, for a similar scent; the flowers are quite similar but purple. Also reported as fragrant by Patrick Worley are A. fimbriata and A. glabrata. He adds that hybrids with these species, unfortunately, did not inherit any fragrance.
Capanea is a genus of epiphytic, bat-pollinated species. The plants require a well-drained soil and may grow quite large, tending to climb or trail. Capanea has been described as lacking scaly rhizomes, but C. grandiflora will occasionally produce scaly rhizomes in cultivation. The flowers are large, hairy, green with brown speckles, and pendulous. I did not think to check for a scent when my plant bloomed, but Patrick Worley reports a cabbage-like odor on Capanea (probably C. grandiflora) in Costa Rica.
Chiritopsis is a genus of about ten species, all restricted to southern China. Only one species is in cultivation in North America. Chiritopsis repanda has only recently been discovered to have fragrant flowers, although it has been in cultivation for several years. This is probably because it also has fragrant foliage, which obscures the scent of the small white flowers. According to Monte Watler, "the blossoms as well as the foliage are highly scented and at night pervade the plant room with a very strong odour which some people may find unpleasant. I find it rather pleasant and normally I have an aversion to strong-smelling plants such as the hyacinth and lily of the valley" ("Chiritopsis repanda var. guilinensis," 1997, The Gloxinian 47(4): 32).
Codonanthe species grow epiphytically in association with ant nests. There are several species distributed throughout South and Central America and the West Indies. All are more or less trailing, and make good hanging baskets. According to Patrick Worley, most species are fragrant to some degree, with C. digna (as C. Frances Batcheller) being one of the most fragrant. In my own experience, I have found only C. carnosa to be fragrant. Codonanthe carnosa was described as the "gingerbread-scented gesneriad" in an article by Anne Crowley several years ago ("Codonanthe", 1985, The Gloxinian 35(2): 18). The beautiful white flowers are deliciously sweet, with a somewhat spicy undertone.
Drymonia species are of easy culture and have attractive flowers; unfortunately, most are too large for indoor culture. Most are lianas, but a few are upright growers, and many have attractive, often patterned, leaves. The flowers may be pollinated by large bees, or possibly even bats. Most seem to have faintly, but not always pleasantly, fragrant flowers. Drymonia alloplectoides, a trailer, has been reported to have a faint sweet scent. Drymonia killipii is an upright grower with handsome foliage and waxy, oddly scented red-purple flowers. The fragrance reminds me of a purple trillium, a scent I appreciate but others do not. Two other species I have found to be faintly fragrant are D. mortoniana, with a sweet scent, and D. serrulata, with a slightly musky scent. Drymonia serrulata is a widespread and variable species, and the various collections differ in their floral scents. One collection in the Smithsonian Institution greenhouses has a pungent scent aptly described as "stink bug" by Christian Feuillet. For an excellent survey of the cultivated species, see David Turleys 1994 article "Drymonia: As I See It," The Gloxinian 44(2): 23-27.
Gasteranthus is still a poorly known genus, but many species are now in cultivation. They are generally difficult to grow and bloom, requiring low light and high humidity. One species, G. atratus, has yellow flowers with a sweet lemony fragrance. Others will surely be found to be fragrant as well.
Gesneria has at least one species with fragrant flowers, G. humilis. Elisabeth Funkhouser described it in her 1984 article "Success with Gesneria humilis", The Gloxinian 34(6): 10-11, "It is a strange odor, not exactly unpleasant, but reminding me of a snuffed-out candle . When I smell G. humilis, I think of the bayberry candles we used to burn on Christmas Eve, letting them burn down and go out by themselves." The pollinator of this odd little plant is still unknown. There are several other species of Gesneria which might have fragrant flowers as well, particularly those with white or greenish flowers, which are presumably pollinated by bats.
Gloxinia has at least two fragrant species. Gloxinia perennis is one of the familiar fragrant gesneriads. I find the frequent comparisons of its pleasant minty scent to toothpaste to be unfair. Unfortunately, this species is too tall for most of us to grow under lights. If you have room in a greenhouse, sunporch, or patio, the plant is most impressive. The selection Insignis is a little more compact, and I have bloomed it under lights. One compact G. perennis hybrid, G. Arion, is also reported to carry the minty fragrance. The other fragrant species, G. lindeniana, is quite unlike G. perennis. The silver-veined dark velvety leaves make it look more like a kohleria, and indeed it was formerly classified as Kohleria lindeniana. David Turley describes the scent as minty, but to me it has a distinct rose scent, sweet but with a slight undertone of decay, like a flower thats past its prime. Other species of Gloxinia are to be expected to be fragrant, including G. racemosa and G. sarmentiana. These species lack a nectary disk, and without nectar, must use another enticement to attract pollinators. However, they may produce compounds that are fragrant to their pollinators but not to us!
Koellikeria erinoides is one of my favorite gesneriads. It is easy to grow, small enough for lights, a dependable bloomer, and has an unusual scent: a delicious spicy smell of coconut, which I discovered on my plant of K. erinoides Red Satin quite by accident several years ago. The fragrance is intermittent, but at times is quite strong on a heavily blooming plant. The pollinator is presumed to be a small bee. Koellikeria erinoides has entered into intergeneric hybrids with Kohleria to produce xKoellikohleria rosea and xKoellikohleria Goblin. Neither of these is known to be fragrant. However, a cross with Gloxinia perennis by Jim Roberts has produced a fragrant intergeneric hybrid: xGlokeria Dragonsong is reported by David and Colleen Turley to have a spicy scent unlike that of either parent.
Lietzia has recently been synonymized under Sinningia, and Lietzia brasiliensis is now Sinningia brasiliensis. However, for convenience I will discuss this species separately. One collection has been distributed with the unpublished (and therefore invalid) name "Lietzia glandulosa." However, this intriguing plant is well worth growing if you are interested in unusual gesneriads. This collection is distinguished by its narrow, deeply serrate, and extremely sticky leaves which are strongly and unpleasantly fragrant. The flowers, on the other hand, have a sweet honey-like fragrance. They are a pale yellow-green with tiny purple speckles on opening, and fade to a creamy white. They make me think of a yawning dragon. Other collections of S. brasiliensis have larger flowers, often more heavily marked with purple, but the scent is less pleasant. The individual flowers last only two or three days, but the bloom period is long, and the plant produces many side shoots which will continue to bloom. All collections of Sinningia brasiliensis are tall growers that require high light levels, and even then they may need staking. Their cultural requirements are similar to those of S. tubiflora, except that they tolerate underpotting quite well. They are easily grown from seed, but may not bloom until their second or third year. A form with pure white, unspeckled flowers has arisen in cultivation, and may prove useful to hybridizers. For more information on Sinningia brasiliensis, see Dave Zaitlins article "Experiences with a New Species of Lietzia," 1990, The Gloxinian 40(4): 9-12.
Napeanthus is a little-known genus. The plants are small growing, require terrarium conditions, and the small white flowers open early in the morning and drop off by early afternoon. Patrick Worley notes that N. costaricensis has fragrant flowers. Napeanthus jelskyi may also be fragrant, but the flowers are so tiny its hard to tell!
Nautilocalyx has had one species previously reported as fragrant, N. pemphidius. However, I have never noted any fragrance on this species small white flowers. Nautilocalyx punctatus, a much larger species, has purple-speckled pale yellow flowers with a faint sweet scent. I would not be surprised to discover that other species in the genus are fragrant.
Nematanthus Santa Teresa is a still-undescribed species completely unlike any other member of the genus, and its large orange-speckled white flower is more reminiscent of a Codonanthe on steroids! This is probably the most powerfully fragrant gesneriad, with a single flower perfuming a good-sized greenhouse. The scent has been described as a combination of fine olive oil and oranges, as drying paint, as rotting tangerines, and as more unmentionable things! The fragrance is obviously not for everybody, and a plant in full bloom in an enclosed space can be a bit overwhelming. The flowers seem to open all at once, with a plant producing several flushes of bloom each growing season. Santa Teresa is an epiphyte with lax stems and velvety leaves. It makes an attractive hanging basket and requires the same culture as Codonanthe and Nematanthus: bright light and a well-drained soil that is allowed to dry out slightly between waterings. It has a semi-dormant period in the winter, when it can be kept cooler and drier. The flowers are produced in the axils of last years growth, so any pruning should be done immediately after flowering. There is another collection of the same species in cultivation, with even larger flowers. I have attempted to cross Santa Teresa with Codonanthe carnosa, without luck; however, other crosses between Codonanthe and Nematanthus have resulted in the hybrid genus xCodonatanthus, and if a cross with Santa Teresa is ever successful, the fragrance may be dominant!
Niphaea is a small Central American genus of small white-flowered herbs. Patrick Worley notes that N. oblonga has fragrant flowers. However, I have never been able to detect any fragrance on this species.
Paliavana is a small genus of shrubs from southern Brazil with large, waxy flowers. Paliavana is closely related to Sinningia, but does not produce tubers. Two species are in cultivation, P. prasinata and P. tenuiflora. Both are fragrant, but in entirely different ways. Paliavana prasinata has campanulate green flowers speckled with purple, which have an unpleasant carrion-like odor. It is presumably pollinated by bats. Paliavana tenuiflora, on the other hand, has lovely deep lavender blooms, much like the wild types of Sinningia speciosa, and they are sweetly fragrant. Paliavana prasinata and P. tenuiflora may be induced to bloom at a smaller size by keeping them underpotted; both require high light levels and must be watered frequently while actively growing.
Paradrymonia has at least two fragrant species. One species that has bloomed in the Smithsonian greenhouses, P. fuquaiana, is reported to have a pleasant scent by Leslie Brothers. I find it to have a slightly pungent spicy or medicinal fragrance. Smithsonian collection 94-220, collected in Ecuador by Rick Dunn, has also been identified as P. fuquaiana, but has a much stronger scent. It has been distributed through the AGGS Seed Fund as "Paradrymonia sp. aff. fuquaiana." The other fragrant species has been offered in the AGGS Seed Fund as "Paradrymonia sp. (costaricana ined.)". Its scent has been compared to cloves.
Rhynchoglossum is unusual in that it is the only genus in the family with species occurring in both the New World and Old World. The plants have pretty flowers that are as close to true blue as any gesneriad comes. Several species are in limited cultivation, but so far only R. gardneri (previously grown as R. notonianum) has been reported to have fragrant flowers. Patrick Worley describes the fragrance as a "sweet orange-blossom scent" although I have never noticed this on my own plant. Several other species of this interesting genus are now in cultivation, and it would be worth checking them for fragrance as well.
Rhytidophyllum species are probably pollinated by bats. Although I did not note the species, the flowers of one plant in the Smithsonian greenhouses had a rank scent reminding me of an animal cage at the zoo. However, other species may have different (and possibly more pleasant!) fragrances.
Sinningia was represented until recently by only one fragrant species: Sinningia tubiflora. This species is not widely grown because it is a tall grower and requires lots of light to bloom, but it is well worth the effort for the large, intensely fragrant pure white flowers. Although the pollinator of S. tubiflora is unknown, it is most likely a long-tongued sphinx moth. Sinningia tubiflora is hardy, as gesneriads go; it has been reported to overwinter successfully in northern Florida. Some people consider the powerful lemony fragrance overwhelming, but I have met at least one person who could not smell it at all!
How things have changed! There are now several other fragrant sinningias in cultivation, as a result of hybridization and introduction of new species. One of the first "other" fragrant sinningias was Peg Conners Apricot Bouquet. This hybrid of Sinningia aggregata Pendulina, S. tubiflora, and S. warmingii has flowers with a toned-down version of the scent of its S. tubiflora parent; and as a bonus, has lemon-scented leaves from its S. aggregata parent. It is unknown whether the compounds responsible for the scented leaves and flowers are chemically similar. However, the fact that the fragrance came through in Apricot Bouquet suggests that it is a dominant characteristic, and should alert hybridizers to the possibility of producing other fragrant hybrid sinningias! There is another plant in cultivation in the Smithsonian greenhouses, unfortunately without a name, that probably represents another of Pegs hybrids. It is obviously a S. tubiflora hybrid, but is more compact, has large pale yellow flowers with a pleasant lemony scent, and slightly fragrant leaves as well.
Several recently introduced Sinningia species are also fragrant, though not to the degree of S. tubiflora. Sinningia guttata, S. villosa, and S. lindleyi, all closely related to S. helleri, the type species of Sinningia, have fleeting, sweet fragrances. The scent of S. villosa has been described as "sweet minty" by Peter Shalit, and that of S. lindleyi as "key lime pie" by Jon Dixon. Like S. tubiflora, the long-tubed white, yellow, or pale green flowers of these species are suggestive of moth pollination. However, the fact that these species are most strongly scented during the day suggests a large, long-tongued bee instead.
Sinningia conspicua is another newly introduced species with a sweetly scented flower. This is one species with a scent I dont find especially pleasant, although others do. The scent has been described as lemony. Plants from wild-collected seeds have proven to be quite variable with respect to growth habit, flower shape and color, and intensity of fragrance. Seeds from a fragrant selection are available through the AGGS Seed Fund. Sinningia conspicua is a close relative of S. eumorpha, which has never been reported to have fragrant flowers, although I would certainly expect it to. Dave Zaitlin has been crossing the two species in hopes of producing plants like S. eumorpha but with the fragrant yellow flowers of S. conspicua. Like S. eumorpha, S. conspicua will produce fertile hybrids with S. cardinalis, S. macropoda, S. leucotricha, and all other members of this group of species. These hybrids will have smaller but more numerous flowers in shades of red, purple, pink, and orange, and will probably not be scented. However, back-crossing to S. conspicua should yield some very interesting plants with larger flowers in a wide range of colors, including yellow, with the possibility of recovering fragrance. Sinningia conspicua, like S. eumorpha, might be persuaded to make the occasional odd cross with the taller Sinningia species. While these crosses have little horticultural merit, it would be very interesting to produce a hybrid with S. tubiflora and see if it is fragrant! Crosses between S. eumorpha and S. tubiflora were produced by Carl Clayberg several years ago, but there is no indication that they were fragrant.
Smithiantha canarina has a slight lemony scent, appropriately enough for its bright lemon-yellow flowers.
Streptocarpus species are among the few Old World gesneriads reported to have fragrant flowers, and even then only six species have been reported, all in subgenus Streptocarpus. Streptocarpus candidus, S. fanniniae, and S. wilmsii are close relatives that are described as being sweetly honey-scented. Maryjane Evans describes S. candidus as having "an intense fragrance of warm honey." On the other hand, S. vandeleurii, S. eylesii (flowers here), and S. wittei are described as having a strong (but not necessarily unpleasant) scent like a mixture of honey and creosote. Most of these species are available from the AGGS Seed Fund; unfortunately, all are rather large growers, and not all selections of these species are fragrant. Martin Kunhardt has been distributing seeds from crosses with some of these species. One cross with S. vandeleurii yielded pleasantly scented flowers (see Peter Shalits 1994 article "Fragrant Streptocarpus HybridsReally!" in CrossWords 18(3): 6), suggesting that this characteristic is dominant in crosses, and well worth working with. All these species should be crossed with more compact species and cultivars, in an effort to bring their fragrance into plants more suitable for indoor culture. The definitive reference on this large genus is Hilliard & Burtts Streptocarpus: An African Plant Study (1971, University of Natal Press), a treasure if you can find it.
Finally, there are several genera of gesneriads in which we would expect to find fragrant flowers, but none have been reported. This may be because they are rarely cultivated and poorly known, or because the fragrances are detectable to their pollinators but not to us. Two such genera are Lembocarpus and Monopyle; both have flowers similar to those of Gloxinia perennis and like that species have no nectary, leading one to expect a fragrance to attract a pollinator. I have specifically checked for fragrance in the flowers of Lembocarpus amoenus and Monopyle flava and detected none. But maybe its just my nose!
This is by no means the last word on fragrance in gesneriads. There are sure to be many more fragrant species out there. There may even be some well-known species that we have overlooked. So the next time you have a plant blooming, stick your nose in and give its flowers a sniff!
This article was originally published in slightly different form in The Gloxinian, Third Quarter 1996 (V. 46, No. 3).