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  lowers have always steered us to new colors and the harmonic use of color, even supplying pigments for
dyes. Skilled gardeners, much like skilled painters, can be judged by how well they manipulate color.
Gertrude Jekyll revolutionized gardening with a sophisticated approach to complementary and contrasting
color dynamics. She was acutely aware of the nuance of color and its proper naming, as she wrote in Color
Schemes for the Flower Garden:
What a wonderful range of colouring there is in black alone to a trained colour-eye! There is the dull brown-black of soot, and the velvety brown-black of the bean-flower’s blotch: to my own eye, I have never found anything so entirely black in a natural product as the patch on the lower petals of Iris iberica. Is it not Ruskin who says of Velasquez, that there is more colour in his black than in many another painter’s whole palette?At Sissinghurst, Vita Sackville-West bled one of her gardens of color and planted only white flowers, a "moon garden" that was designed for night viewing. Being a contrarian, I toyed with the opposite notion, a garden of all black flowers (a noon garden?) and began to compile a list. What soon became clear is that black is probably the rarest of flower colors and that "true black" species, not horticultural creations such as black tulips, are rarer still. Lisianthius nigrescens of Mexico, La Flor de Muerto, is an intriguing plant. It is one of the rarities of the plant world, a black flower. Native only to the states of Veracruz, Oaxaca, and Chiapas in Mexico, the black lisianthius has been sporadically collected since its first description in 1831, and documented collections number less than two dozen. I set to planning a collecting trip and was lucky to recruit an old botanizing partner, Dr. Melvin Shemluck, to be a second set of eyes. By studying pressed specimens at Harvard's Gray Herbarium we familiarized ourselves with the look of its hanging tubular flowers, compiled a short list of possible sites, and knew when we were likely to find the plant in flower. We zeroed in on a site in the Zapotec Indian region of Oaxaca where the plant had been collected in 1939 by Richard E. Schultes. We returned to this site and hoped that after 50 years the black lisianthius still bloomed in the hills of the Chinantla region. Our goal was to bring back live plants or preserved specimens for further study of its pigmentation and to garner a few clues into its pollination biology. |
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 In Oaxaca City, the regional biological research center agreed to collaborate and assigned a first-rate field botanist, Raul Rivera, to accompany us. We approached the targeted area from the lowland tropical farmland of Veracruz and headed south into the Sierra de Villa Alta, a mountainous landscape inhabited by the Zapotec people, an old foe of the Aztecs. The road put the lie to the line on the map. Instead of the promised fat red route, we were navigating a two-rutted stone yard, obviously a road the mapmaker had never traversed. We bumped along, occasionally stopping to botanize a patch of intact forest in this rural checkerboard, engaged in a chess match with agriculture. A few giant strangler figs gave us the impression of how mighty a forest this once was. Occasionally a broken tree limb lay next to the road and we would delight in the epiphytic vegetation anchored onto the bark, beautiful bromeliads and species of orchids such as Hexisea. In the full heat of the sun these plants would eventually die, so we removed specimens for herbarium sheets and for the botanical garden back in Oaxaca. We passed upward into a pine zone and spotted huge sweetgum, Liquidambar styraciflua, a species found as far north as New York. On the cusp of the fourth hour we were rewarded. We spotted a roadside tree of Saurauia aspera, a plant of the kiwifruit family, which also yields an edible fruit. Remembering that Schultes had listed it as an associated species with lisianthius, we redoubled our efforts at scanning the passing vegetation. After a mere fifty yards, a constellation of little black bells appeared, just three feet out my window. In a narrow band of vegetation, sandwiched between the road and a burnt-over field, we found a few dozen plants of various ages. We felt awash with relief that the jostling days on rough roads and weeks of preparation were not in vain, and happy that the fires had halted where they had. The plant was a single stalked herb to 5 feet, rather open and sparsely branched. But the inch and a half flowers were a special breed. Depending on the angle of sight they were a blackish purple, like the skin of an eggplant, or inky black, fully devoid of color. In bud the emerging flowers looked like glistening drops of coal oil, and when opened they presented a tubular bell of black satin. We parked our vehicle and began the process of preparing specimens for the herbarium and laboratory. On returning from our fieldwork we connected with Dr. Kenneth Markham of the New Zealand Institute for Industrial Research and Development, the foremost authority on floral pigments of lisianthius and its relatives. With our samples he decoded what pigment molecules are at play in the black tubular blossom. Floral pigments are made of hundreds of different molecules that fall into only a few different classes: flavonoids, carotinoids, and betalains. Flavonoids are water-soluble and are found in the vacuoles of plant cells. A number of flavonoids are known. Anthocyanins bring red, blue, and purple coloring to flowers such as delphiniums, geraniums, and roses and such fruits as grapes and plums. Other flavonoids, such as aurones, flavonals, and flavones, are responsible for cream or yellow pigmentation. Dr. Markham found two anthocyanin pigments. The percent dry weight of these pigment molecules in the dried flower tissue was the real surprise, coming in at a whopping 23%. According to Dr. Markham, this is extraordinarily high and compares to only 1.1 to 1.4% found in the purple florist's lisianthius. Other flavonoids were also found and may be serving to enhance color intensity. The possiblilty of transgenic applications, using genes from the Flor de Muerto to create new strains of florist's lisianthius, is intriguing, and we hope to explore this potential with our Mexican and New Zealand colleagues in the future.  |
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