Pacific Plant Promotions: Deppea splendens

By: Kathy Musial

Kathy Musial is curator of living collections at the Huntington Botanical Gardens where she has worked for more than twenty-five…

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Announced in the last issue of this journal, the Pacific Plant Promotions is a program for distributing unusual, rare, or challenging plants–unattainable through normal retail channels–to plant enthusiasts through Pacific Horticulture. This first offering is of a choice plant now thought to be extinct in its native range in southern Mexico.

When Pacific Plant Promotions (PPP) was in the planning stages, we agreed that a blockbuster plant was needed to launch this project. Deppea splendens, whose story is as intriguing as the plant itself, leapt to our minds. A more fitting choice could hardly be imagined, as this species embodies both the driving force behind PPP and the importance of botanical gardens and their collections.

Deppea splendens. Photograph by Don Mahoney

Deppea splendens. Photograph by Don Mahoney

Shortly after I started working at the Huntington Botanical Gardens in 1982, I attended my first quarterly meeting of the “Conference of Botanic Gardens and Arboreta of Southern California”. These meetings are a good opportunity to see what’s new at other gardens, discuss topics of common interest, and keep in touch with each other. They are also a good venue for gardens to distribute excess plants from their collections. At the Fall 1982 meeting, the Huntington brought several plants cryptically known only as “unidentified Rubiaceae, HBG #46808”, grown from seed collected by Dennis Breedlove and Bruce Bartholomew at Cerro Mozotal in Chiapas, Mexico. Unidentified or unknown species often have a singular appeal to my colleagues, and these were eagerly snatched up. Some even sported the dangling flower clusters, adding to the allure. We had enough plants to continue distributing them at subsequent meetings and to offer a few at our annual plant sale, though we still had no name for it. Over the years this plant came to occupy a near-mystical status and I was often (and am still) asked about its identity. This taxon was not scientifically described until 1987 by Dennis Breedlove and David Lorence; two more years went by before I became aware that the mystery plant finally had a name.

Deppea is a Neotropical genus of twenty-five species of shrubs or small trees, most of which are found in the mountains of southern Mexico and Guatemala. Deppea splendens was first collected as pressed specimens by Dennis Breedlove in 1972 in Chiapas, Mexico, as part of his ongoing work for the Flora of Chiapas. More specimens were collected in subsequent years, but only once was living material brought back, from a collection made by Breedlove and Bruce Bartholomew in November 1981. Seeds of Breedlove and Bartholomew #55758 were given to the University of California Botanical Garden and the Huntington Botanical Gardens in January 1982. Seedlings grew and flowered at the UC Botanical Garden, and some were distributed to Strybing Arboretum, the Saratoga Horticultural Research Foundation, Western Hills Nursery, the Golden Gate Park Conservatory, and a few Bay Area nurseries. Most of these perished in the 1990 freeze; the fate of the rest is unknown. Strybing still has one plant, which has been propagated by cuttings and distributed at its plant sales and given back to the UC Botanical Garden.

At the Huntington, aside from the seedlings that were distributed, six were planted in 1982 in two locations in the Subtropical Garden; three more were added in 1984. Sadly, six of these succumbed to the December 1990 freeze. In 1994, cuttings of the surviving three were given to Steve Brigham of Buena Creek Gardens to propagate for distribution at the annual conference of the American Association of Botanic Gardens and Arboreta, hosted by the Huntington that year. Buena Creek Gardens later sold and gave away many of the remaining plants. In 1996 cuttings of these three clones were given to Rancho Santa Ana Botanic Garden (RSA). We later lost one of our plants due to a scale infestation but were able to get this clone back from the material given to RSA—a good example of why rare taxa should be shared.

In 1993 I learned from Dennis Breedlove that the only known site of Deppea splendens had been cleared for farming as of 1986 and that it was now presumed extinct in the wild. A recent conversation with him confirmed this, and that no other sites had ever been located, though he speculated on the slim chance it still existed in the mountains across the Guatemalan border, an area virtually closed to outsiders. Therefore all extant germ plasm is now known only in cultivation. After first learning of its apparent demise I began trying to track down the seedlings Huntington had originally distributed to determine how many clones might still be in existence. Initial inquiries elicited only one other plant, at the Mildred Mathias Botanical Garden at UCLA. Since then, with the additional sleuthing of Bart O’Brien, others have come to light, so that we now have documented at least seven clones. I am still trying to locate any seedling plants existing from the original distributions labeled Breedlove and Bartholomew #55758 or HBG #46808; anyone who might have plants or information should contact me so we can assemble as complete an ex situ germ plasm collection as possible.

Deppea splendens was only known from a canyon on the south slope of Cerro Mozotal in southern Chiapas, where it naturally occurred as a fifteen- to twenty-five-foot shrub or small tree in pine-oak cloud forest within sight of the Pacific Ocean. There it was occasional on the steep canyon slope but abundant along streams. In cultivation it is an open multi-trunked shrub about eight feet tall, somewhat dichotomously branching with leaves in terminal whorls. Easily the showiest member of the genus, D. splendens is notable for the six-inch-long, wiry peduncles from which dangle its corymbose inflorescences. Two-inch yellow to orange flowers protrude from showy claret, octopus-like calyces. The tubular flowers imply hummingbirds as the pollinators, but the capsular fruits have never been observed on the Huntington plants. Hand-pollination has been attempted by Dylan Hannon at RSA, so far without success; fruits form but abort before maturity. Flowering typically occurs in late summer in San Francisco and in spring and fall in Southern California, though in the south blooming is often irregular, with no distinct season. The Huntington plants came into bud in December, but with the cooler nighttime temperatures in January the flowers aborted. Indeed, this species is very susceptible to cold and needs a frost-protected site; temperatures in its cloud forest habitat vary little from season to season—rarely cold or hot. At the Huntington it is planted in a shaded area, not just for cold-protection but to better tolerate our hot summers. Too much dryness during bud development will also cause flowers to abort; ours are watered weekly. In colder regions, it might be grown in containers like a tender fuchsia.

The Huntington Botanical Gardens will be offering cutting-grown plants (propagated at RSA) of its three clones of Deppea splendens. To order one, see the Pacific Plant Promotions reservation card (opposite page 57) for details.

The next offering from Pacific Plant Promotions will be in the October issue of Pacific Horticulture.