I stIll remember exactly the time I became enchanted by gentians in the wild. I was fortunate enough to accompany a group of botanists in early October of 2007 on a visit to the Warren Grove National Guard Bombing Range in Warren Grove, New Jersey. The range encompasses nearly 10,000 acres of diverse habitat in the Pine Barrens, and laid out in front of me was a field of thousands of impossibly azure pine barren gentian (Gentiana autumnalis) blossoms. I turned to my companions and asked how such a scene was possible, in New Jersey no less? “The National Guard periodically drives their tanks over here and blows stuff up”, and the disturbance and accompanying fire regime helped to create the rich mosaic of species before my eyes. My jaw agape, I asked specifically how such a flower could be so blue having never before encountered its rival in my 15 years in public horticulture. “No flower is bluer than the gentian.” Returning to NYC that evening I felt inspired to find out more about this plant and was happy to find myself not alone in my amazement. Many poets have waxed over the particular joy of encountering gentians in the wild. William Cullen Bryant in his ode “To the Fringed Gentian” writes,
Thou waitest late and com’st alone,
When woods are bare and birds are flown,
And frosts and shortening days portend
The aged year is near his end.
Then doth thy sweet and quiet eye
Look through its fringe to the sky,
Blue – blue – as if that sky let fall
A flower from its cerulean wall.
D. H. Lawrence once famously quipped, “Oh what in you can answer to this blueness?” In my estimation, few plants can. Herein lies the beguiling attraction of the gentian. They are regarded as exceedingly beautiful, almost as mythical and rare as an orchid, and difficult to grow and manage in the garden. Although many species occur in North America as natives, and a few of these are occasionally cultivated, the majority of the 350 species in the genus Gentiana are adapted to chiefly alpine and cool climate regions worldwide. In the northeast and north central states of the US, gardeners struggle with them to achieve a modicum of success despite the warmer and more humid conditions. My aim with this article is to present two species, pine barren gentian (Gentiana autumnalis) and fringed gentian (Gentianopsis crinita), with which I have had good success in cultivation. I will discuss the natural history, pollination biology, and conservation status of these plants in the wild along with my observations regarding seed collection and cultivation.
Pine barren gentian (Gentiana autumnalis) is a denizen of the Atlantic coastal plain and can be found in pine savannahs and sandhill ecosystems. It prefers to grow in open, grassy areas with damp acidic sandy soils. The natural distribution of pine barren gentian is somewhat odd, the bulk of its populations are found in northeastern South Carolina through North Carolina (the state from which the type specimen, which actually predates Linnaeus, was collected) and into the southeastern corner of Virginia. Then it reappears in small, scattered populations in southern Delaware and in the Pine Barrens of southern New Jersey. In terms of its conservation status, the plant is listed as globally vulnerable (G3) indicating that it is very rare throughout its range. It is found only in restricted areas (even if abundant at some locations) and comprised typically of between 21 and 100 occurrences or between 3000 to 10,000 individuals. South Carolina, North Carolina, Virginia, and New Jersey rank it as imperiled or critically imperiled while the species has been extirpated from the state of Delaware. As is the case with many of our rare plants, their populations are in decline due to anthropogenic factors, primarily loss of habitat and fire suppression. Although not extremely rare, this species does occur in threatened habitats. This stunning plant is an early successional perennial, which responds favorably to periodic burns.
One of the very botanists who introduced me to the charismatic plant has studied the effects of prescribed burns on its population demographics. Dr. Walter Bien and Dr. Ryan Rebozo have shown that regular burns of populations on the Warren Grove Bombing Range have resulted in greater plant density and flowering over undisturbed populations. Furthermore, disturbed sites showed the greatest colonization by arbuscular mycorrhizal fungi as well as the greatest insect visitation and seed set. Studies like this one can help determine management strategies to ensure the future survival of pine barren gentian.
Plants arise from thick fleshy roots and produce slender, wiry stems with narrow leaves. Those thick roots will become important when discussing the propagation of Gentiana autumnalis. Bloom time for this species ranges from October in the north of its range into December or even January in the southern portions of its range. They are rather inconspicuous unless they are blooming. Usually one, but sometimes two to three flowers will open at the terminus of the branch. Bright sunny days seem to coax the flowers to open while they remain shy and closed on cloudy days. The corolla is quite large in comparison with the overall size of the plant and tends to be a brilliant blue, which can very from “sky blue” to darker, richer hues of blue. There is even a great population of pale purple flowers growing at the Franklin Parker Preserve in Chatsworth, New Jersey. The throat or interior of the corolla is heavily speckled with whitish green dots. A fascinating feature of gentian flowers is the prominent pleats found between each pair of fused petals. While not treated here, the bottle gentian bears flowers that never open, and its pollinators must be robust enough to squeeze into the narrow aperture at the top. Once inside the flower can expand like a bellows or accordion to accommodate larger pollinators like the bumblebee. The pine barren gentian with its open corolla has no problem making room for any size pollinator! Lots of busy pollinators ensure good seed production.
Due to the late season of its bloom, the window for seed collection can extend into early winter. Ripe seed will be light brown in color and is best sown immediately when fresh. Some authors indicate that it can be stored cold over the winter and sown in the spring, but I have experienced better germination when sown fresh. We use a standard germination mix as soil media. A good friend had sown some seeds in a germination tray with good results but experienced a great deal
of seedling mortality after pricking out the seedlings that following spring. It seems that the seedlings need to remain undisturbed in the tray, no matter how crowded they may seem in order to better develop that thick fleshy root I mentioned earlier. Even if they are large enough to handle, resist the urge to disturb them. The following season, with larger roots established and a store of reserves to draw upon, the success rate for transplanting was near 100%. The seedlings were then transferred to a deep plug tray filled with a 1:1 ratio of peat and sand. Some of the plants even produced small flowers only two years from seed.
Given where the plant can be found in the wild might lead you to conclude it likes drier soils, perhaps because of the fungal relationships it forms. However, over the course of growing this plant these past four years, I have observed that it prefers to be kept wetter when actively growing. I have seen it used as a companion plant for bog container gardens, happily growing alongside pitcher plants and cranberries. Our plants have been repotted once from the plug trays so that I can display robust vigorous plants in the garden.
Fringed gentian (Gentianopsis crinita) is no less alluring than its pine barren cousin but perhaps more elusive. The distribution of this plant stretches from Maine south to Maryland, west to Iowa and north to Manitoba. There are also disjunct populations along the Appalachian Mountains in Virginia, North Carolina, and northern Georgia. It grows as an annual or biennial herb and, as such, the locations of populations can shift depending upon how successful seed dispersal is in any given year. Its ephemeral nature makes it difficult to truly assess its conservation status. Most states list it as threatened with many historic locations. The early-successional habitat of this species has declined throughout its range due to reforestation. New England and the northern central US were about 30% less forested 100 years ago than than they are now, having been cleared mostly for timber, farming and other agricultural purposes. Climate may also have an adverse affect on this species, particularly since plants flower late in the season. Furthermore, the scattered populations are often made up of only a few surviving individuals. In their article, Letendre and Hull have shown that small populations are less effectively visited by insect pollinators and therefore produce less seed. Fringed gentian prefers rich most soil found in wet meadows, low woods, and stream banks. Thanks to human disturbances it can be found in moist areas along power line cuts and low roadside ditches.
Plants have simple, entire, opposite sessile leaves borne on a branched stem growing between 1 to 3 feet in height. The deep blue- purple flowers, about 5 cm (2 in.) in length, are individually stalked on a long peduncle. The four wide petals at the top of the throat of the flower are rolled up in a spiral cone shape in bud. The flowers open in the sun and close in the shade. The petal edges are fringed with feathery narrow tapering teeth. The fruits are borne in a spindle-shaped capsule with a slender beak producing many seeds. The seeds bear numerous tiny projections, which make them easily dispersed by the wind. Fringed gentian appears to benefit from the presence of mycorrhizae, which seem to play a role in inducing and breaking winter dormancy and suppressing soil pathogens that cause root disease.
In much the same way as with pine barren gentian, I have greatest success using fresh seed and sowing immediately in the late fall/early winter. My initial attempts involved sowing older seed onto standard moistened germination mix and placing the tray into the refrigerator for 12 weeks cold treatment. Once removed from the cold treatment the tray was placed on a heat mat, yet yielded poor germination. The seedlings that did germinate were pricked out and transplanted but never really grew much beyond that point. Fortunately, I have a good source of seed from Connecticut and was able to secure a fresh batch. After sowing the fresh seed, I placed the tray outside in a cold frame with a wire mesh top. The mesh was used to prevent mice and rodents from digging around in the flats as I was also growing bloodroot and trillium from seed. The tray sat out all winter, exposed to the elements and at times buried in heaps of snow. As spring arrived, I checked on my tray and was delighted to find that a carpet of seedlings had sprouted! I concluded that not only was fresh seed necessary but the kind of outdoor cold treatment that a tough NY winter can mete out proved the answer. By June, the seedlings were large enough to handle and were pricked out into cell trays with Metro Mix as the medium. They have been kept evenly moist and have put on 6-8 inches of growth to date. Half of my plants will be set out into the garden while the other half will be kept in the Quonset for seed production. Of course, I have no guarantees that new plants will be successfully integrated in the garden, but the fun is in trying anyway.
Despite their mythical status and the perception that they are difficult to propagate, these two beautiful gentian species have proven to be quite attainable and rewarding in cultivation. While I still enjoy the thrill of the hunt for these plants in the wild, growing them in the garden has made it all the easier to become enchanted all over again.
BIEN, Walter and REBOZO, Ryan R. 2014. The influence of disturbance on the demography of the rare pine barren gentian (Gentiana autumnalis) in New Jersey. Biology Department, Drexel University Conference Paper 99th Annual ESA Conference.
LETENDRE, K. and HULL, J.C. 2004. Effect of population size on insect visitation of Gentianopsis crinita (Frole.) Ma. (fringed gentian). Department of Biological Sciences, Towson University, 8000 York Road, Towson, MD 21252 USA .