PROPAGATION of THREE ENDANGERED CONRADINA SPECIES for ORNAMENTAL USE Susan R

As clippings, leaves, prunings, etc. are added, I mix dead rats, snakes, and sadly, birds. (At one time, the kid themup thoroughly, then tramp them down. Separate next door had a BB gun with which his parents were con layers of leaves, grass clippings, etc. do not compost nearly vinced he never shot at a living thing!) A surprising as well as they do when mixed together. Homogeneous amount of paper (mostly from packaging used on garden layers, particularly of large, flat leaves (such as fiddle-leaf supplies) has composted nicely. None of such miscellanea fig) tend to form impenetrable masses that impede aera has ever been apparent in the final product. At the Univer tion and even percolation of water, both of which are im sity's figure of a nickel a pound for disposal of garden portant in composting. Each time I add 6 inches or so to trash, these compost heaps have saved the city hundreds the pile, I tramp it down leaving the top hollowed out to of dollars over the years. help rain penetrate. (In really dry weather, I use the hose.) When adding much coarse woody material, I add a few pounds of high nitrogen fertilizer to encourage bacterial A Garden Workbench decomposition. A recent press account (3) quotes anen Every serious gardener needs a work area, and a work gineer working on trash disposal as saying, ". . . palm bench eliminates a great deal of "stoop labor." Kipling fronds don't break down regardless of the environment." wrote: "Oh, Adam was a gardener, and God who made Not knowing about this, chopped up palm fronds have him sees, that half a proper gardener's work is done upon long been one of my favorite composting materials! I do his knees." But with every passing year, the knees get more NOT add soil. The local "soil" makes excellent concrete reluctant to cooperate! In Fig. 1, the location of my garden blocks, but is useless for composting. workbench can beseen against the wall of the garden shed. As Darwin pointed out over 100 years ago, earthworms It is of very simple, but weatherproof, construction. It is are marvelously beneficial to soil. But our sand had no shown in its usual state, which is cluttered, gloriously clut earthworms, so I added a quart of "fishworms" when I tered, with bags and pots of this and that, small tools, con started composting. Today, their descendants flourish tainers, stakes, and plants in various stages of propagation. throughout the garden. Every gardener needs such a totally unseen work area, and Now for the simple secret of "composting the easy very few of my neighbors even know this one exists. way." I do NOT attempt to "turn over" a complete pile. Who needs jogging and exercise machines when com That No. 1 section is about 7 cubic yards and my sacroiliac post heaps and a garden workbench can provide so much aches to think of doing so! Instead, I dig each heap out healthy, useful, and enjoyable exercise.? from the bottom using a digging fork and a long handled shovel, the product from the bottom of each heap going Literature Cited onto the top of the next. Ultimately, when I have dug a big enough "cave," the heap collapses and new material 1. American Colloid Company. 1988. Iron Enersol. Tech. Data Sheet goes on top. Depending on need and weather, I may dig 31A014 9/88T. out only a bushel or so at a time, or (when the weather is 2. Bonsall, W. 1990. Making hot compost. Fine Gardening 15:34-37. 3. Fechter, Michael. 1990. Expert wants to trash traditional landfills. cool and I need exercise) I turn compost over for an hour The Tampa Tribune, Oct. 15. pp. 1 & 5. on end. Wonderful exercise! 4. Hammer, Marie. 1988. Christmas trees, gift boxes just add to state's Off and on over the many years, more than plant ma garbage woes. The Tampa Tribune-Times, December 25 terial has cycled through these compost heaps including 5. Obreza, T. A., R. G. Webb, and R. H. Biggs. 1989. Humate materials: Their effects and use as soil amendments. The Citrus Ind. 70(10):36- 38.

Proc. Fla. State Hort. Soc. 103:381-383. 1990.

PROPAGATION OF THREE ENDANGERED CONRADINA SPECIES FOR ORNAMENTAL USE Susan R. Wallace Curator of Endangered Plants and growth habit vary among individuals, but selected clones Bok Tower Gardens have showy pale blue flowers and compact foliage. Their nat Lake Wales, Florida 33859 ural disease and pest resistance, cold hardiness, and drought tolerance make them ideal for low maintenance, low water landscapes. Additional index words. Conradina glabra, Conradina grandif- lora, Conradina brevifolia, endangered plants, native plants, endemics, scrub plants, mints, ex situ conservation. Development pressures and relentless habitat destruc tion have put many rare Florida endemics at risk of extinc tion. Bok Tower Gardens' Endangered Plant Program is Abstract Three rare Florida scrub endemics, Conradina bre- bringing these rare species into cultivation for research vifolia Shmners, Conradina glabra Shinners, and Conradina and safe keeping. While ex situ populations will be main grandif/ora Small, which havebeen brought into cultivation tained at The Gardens, the goal is the development of in Bok Tower Gardens' Endangered Plant Program, have technology to establish new populations on protected sites promising ornamental potential. Attractive woody mints with (o). aromatic needle-like foliage resembling the herb Rosemary, Three of these species—woody mints of the genus Con all three species root readily from cuttings and grow rapidly radina—which are reduced to alarmingly low population to saleable size with standard nursery practices. Flower color numbers in the wild, have responded very well to cultiva- Proc. Fla. State Hort. Soc. 103: 1990. 381 tion and show real horticultural merit. All of them have narrow, sessile, revolute leaves which look almost needle- like and appear in false whorls on the stem (actually tufts of opposite leaves with virtually no internodes). The foliage has a pungent, but not sweet, minty odor, especially in C. glabra. The flowers, which range from white to bluish to laven der, and are variously spotted with purple, are typically mint-like but distinguished by a conspicuously geniculate corolla tube, a characteristic of the genus (2). Flowers ap pear sporadically throughout the year but are most abun dant in late winter and spring. Butterflies and bees are frequent visitors. Conradina glabra Shinners, known from only a small inland area of the Florida Panhandle, is possibly the most attractive of the three species, with shiny dark green foliage and a naturally dense busy habit (Fig. 1). Plants average 30" in height, with leaves 1/2" to 3/4" in length. Aesthetically, the compact growth and fine texture resem ble heather and the plants provide an excellent contrast in a landscape of broadleaved species. Conradina brevifolia Shinners (considered conspecific to C. canescens by Wunderlin (4)) is known from southern Polk and Highlands counties in Central Florida (Fig. 2). Plants average 24" in height, with smaller puberulent Fig. 2. Conradina brevifolia adds a silver gray note to the garden with leaves about 1/2" in length, and a more open, even rangy, puberulent leaves and pale lavender blooms. growth habit. The silver-gray foliage is an attractive accent Pholo credit: Steve Christman in a green landscape and a good foil for bright flower colors. Gray-leaved plants like Artemisia and Santolina are Tower Gardens' Endangered Plant Program. However, used to good effect in English and Mediterranean gardens, preliminary work suggests that this species propagates just but Florida has few such garden species. as readily as the others and is arguably even more attrac Conradina grandiflora Small, found along the Central tive, combining the gray foliage of C. brevifolia, the florifer- Atlantic coast, is the easiest to grow and most floriferous ousness of C. grandiflora, and (at least in some individuals) of the Conradinas (Fig. 3). The showy one inch flowers the compact form of C. glabra. appear from early winter through late spring. Leaves are All of the Conradinas exhibit differences among indi larger, about one inch long, glabrous above, gray beneath, viduals in the same population. Clonal variations in growth and generally more widely spaced. Plants range up to four habit and flower color are readily apparent, and more sub- feet tall with a somewhat sprawling habit, but may be pruned for a compact shape. The related Conradina canescens Torrey and A. Gray, which is a fairly common and morphologically diverse species along the Northern Gulf coast, is not part of Bok

Fig. 1. Conradina glabra resembles heather in the landscape with fine Fig. 3. Conradina grandiflora is the most vigorous of the group with textured foliage and myriads of little flowers. showy blooms that are attractive to butterflies. Photo credit: Jonathan Shaw Photo credit: Jonathan Shaw

Proc. Fla. State Hort. Soc. 103: 1990. 382 tie differences in growth rate and propagation vigor show into gallon containers where they reach saleable size within up over time. Because our ex situ plant collections are in a growing season. tended to be genetically representative populations, our All three species respond well to pruning when young, sampling techniques are deliberately random and often in producing more compact growth and an even looking clude individuals which are oddly shaped or poor bloom crop. We have not pruned mature plants of C. brevifolia or ers. However, we would expect that plants grown for land C. glabra, since the plants remained small and compact scape use would be selected for their horticultural merit enough without it. However, to conserve space we have and only those with the best shapes and most attractive had to cut mature C. grandiflora in half, and to good effect, flowers would be propagated. It is for this reason, the de producing renewed bushy growth. crease in genetic diversity, that bringing rare species into The Conradinas have been among the easiest species commercial propagation may not be a valid conservation to grow in our Endangered Plant Program, and on the measure. whole they respond well to standard nursery practices. However, two problems show up often enough to be worth Materials and Methods mentioning. Tip cuttings three to four inches long were made in the Like most native Florida species, Conradinas grow field from wild plants, misted with water from a spray bot naturally in acid soil. However, our irrigation water is well tle, and sealed in plastic bags. Cuttings were immediately over pH 7 and nutritional deficiencies show up frequently. placed in the darkness of an insulated picnic cooler, over This is a common problem in Florida nurseries among ice, but not in direct contact with the ice, and held under other crops and cultural practices must be adapted to re these conditions from 4 to 36 hours until returned to the duce the pH of the water or the soil mix and shorten pro propagation facilities at Bok Tower Gardens. duction time. Chlorotic Conradinas also respond quickly The lower one inch of leaves was stripped by hand to a spray of Chelated iron (Ortho Greenol, two tables from each cutting. Some cuttings were treated with poons per gallon). Rootone F (0.2% NAA, 0.1% IB A). Cuttings were then Conradinas, like other species of the Florida sand struck in four inch plastic pots containing a soilless mix of scrub, are adapted to dry, rapidly draining soils. Metro Mix 500 with 15% perlite by volume. Pots were Phytophthera root rot has appeared in container grown placed in 30% shade under intermittant mist (10 seconds plants, although less frequently in Conradinas than in every VAz minutes in summer or 10 seconds every 5 mi some other scrub species. Although the problem is treata nutes in winter). Bottom heat was used when night temper ble with Subdue or other such fungicides, our strategy has atures ranged below 65°F. When rooted, pots were re been to use a very light soil mix and reduced irrigation. moved from mist and placed in full sun. Conradinas show good potential for use in the new Florida landscape. Now with reduced water availability and more frequent widespread freezes, the horticultural indus Results and Discussion try must find new plants and develop new technologies to After propagating the original wild material, we have meet the state's needs. Native species like the Conradinas since re-propagated from mature plants in the collection are well adapted to low water, low nutrient, and high light several times over the last four years. Results have been regimes, they have a natural disease and pest resistance, consistent over time and among all three species and are and are cold hardy at least as far north as their natural summarized here. ranges. Cuttings will root any time of year, although most vig C. glabra and C. grandiflora are listed on the Regulated orous rooting occurred, as expected, from slightly har Plant Index and are protected by Florida statute. However, dened new growth taken in late summer. Rooting percent the law specifically encourages commercial propagation ages ranged from 76% to 88%. The hormone treatment with written landowner permission and a permit from the makes no apparent difference. Division of Plant Industry. C. brevifolia, currently not a pro We stick the cuttings directly into four inch pots simply tected species, should be a candidate for both federal and to avoid the labor of transplanting and because it is easier state listing. C. canescens is still a fairly common species and to track individual clones. However, where bench space not protected by law. under mist is limited, we see no reason why cuttings could not be rooted more compactly in flats and later trans Literature Cited planted. The pots were removed from under the mist when the Christman, S. P., and W. S. Judd. 1990. Notes on Plants Endemic to cuttings felt tight in the soil with a gentle tug and when a Florida Scrub. Biological Sciences, No. 1, 1990. Gray, T. C. 1965. A monograph of the Genus Conradina A. Gray few roots appeared at the side of the pot. This happens (Labiatae). PhD Dissertation, Vanderbilt University, Nashville, Ten consistently at about five weeks. nessee. Plants are grown in the four inch pots until the root Wallace, S. R. 1990. Uprooted and paved over: Rare endemics find a new mass is well developed and the top growth is about six home in a Florida botanic garden. Botanical Journal of the Linnean Society. In press. inches high, after which they are planted into natural soil Wunderlin, R. P. 1982. Guide to the Vascular Plants of Central Florida in our collection beds. Extra plants have been stepped up University Press of Florida.

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