SODERHOLM: DOMBEYA INTRODUCTIONS 477

and high light intensity—which endow it with In addition, offshore production of flowers and the capacity to grow a host of material. foliage is on the increase in Latin Amer Applications of advances in technology—photo- ica and the Caribbean area. periodism, insect and disease control, plant nu trition, plant breeding and others—along with Florida's natural resources and the entrepre- LITERATURE CITED neurship of flower growers and nurserymen, 1. Brooker, John R. and Smith, Cecil N. "Changes in the Marketing of Foliage Plants," Proc. Florida State Hort. have contributed to the industry's growth. Soc. 75: 439-442. Since by far the major markets for cut 2. Federal-State Market News Service. Florida Shipment 1966-67 Seasons—Flowers and reports for preceding seasons. flowers are the nation's population centers, Orlando: 1967. 3. Florida Crop and Livestock Reporting Service. Florida Florida growers must compete with greenhouse Crops—Flower and Foliage Report. Orlando: April 18, 1967. growers located closer to market. Sellers of 4. Smith, Cecil N. and Brooke, Donald L. The Florida Chrysanthemum Industry. Fla. Agr. Exp. Sta. Agr. Econ. every Florida floricultural crop other than gladi Mimeo. Report 56-10, 1955. 5. U. S. Bureau of the Census. 1964 United States Cen olus3 face competition from growers located sus of Agriculture—Preliminary Report. Washington: U.S. close to market, and for some commodities, from Department of Commerce, 1966. 6. U. S. Census of Agriculture: 1959, Vol. distant growers in California and elsewhere. V, Special Reports, Part I—Horticultural Specialties. Wash ington: U. S. Government Printing Office, 1962. 7. U. S. Crop Reporting Board. Flowers and Foliage Plants—Production and Sales, 1965 and 1966 and preceding 3Gladiolus, nevertheless, competes with other floricultural reports (entitled Cut Flowers—Production and Sales). products in the market. Washington: U. S. Department of Agriculture, 1957 to 1967.

EVALUATION OF DOMBEYA INTRODUCTIONS FOR NEW ORNAMENTALS FOR FLORIDA

P. K. SODERHOLM one or more of these characteristics; and there fore Dombeyas, up to now, have not gained Crops Research Division popular acceptance in the home garden. Agricultural Research Service (Lindl.) Benth. & Hook. U. S. Department of Agriculture F., a familiar to South Florida gar Miami deners, was brought into the country many The U. S. Plant Introduction. Station has in years ago from the Malagasy Republic. A com troduced 14 known species of Dombeya in the mercial nursery catalog listed it in 1938, but last 60 years. Several of these were obtained its actualintroduction surely predated that list through the efforts of E. A. Menninger of Stuart, ing by many years. The earliest introduction Florida, between 1951 and 1957. In this came to the Plant Introduction Station in 1943 of over 200 members we have only scratched the under P. I. (Plant Introduction) 145912. surface by our evaluation of so few species. The "Pink Ball" or "Mexican Rose Tree" (2, 3) Dombeyas are native of eastern Africa from as it is commonly known, proved too large a Ethiopia to South Africa, including Malagasy subjectfor most home gardens. It reaches a Republic and the . height of 20 to 30 feet, and will attain an equal Most of the introduced species have con spread if allowed to go unpruned. spicuous, colorful flowers, appearing over a 4 The flowers, delicate pale pink and white are to 6 week period. In Florida the earliest species highly fragrant and beautiful in themselves, but begin flowering in September and the latest because they are borne in large pendulous um reach their peak of bloom in March . bels, they are hidden by the dinner plate-size Not all species produce plants of outstanding leaves. Flowers appear through December and beauty resulting from 1) over growth; 2) sparse January in Florida. branching habit; or 3) the pendulous, hidden D. x cayeuxii Andre, P. I. 19897, was in nature of theflower heads. Unfortunately, the troduced by the U. S. Department of Agriculture majority of the early introductions manifested from Madeira in 1907 and again from Cuba in 478 FLORIDA STATE HORTICULTURAL SOCIETY, 1967

1935 as P. I. 110682. This hybrid between D. Leaves are 2 to 10 inches long, ovate, cordate wallichii) are dominant. Therefore the hybrid at base, and stellate tomentose on both surfaces. first to be raised in the genus. Lateral nerves are prominent beneath. New In Florida it also flowers during December flushes are reddish. In its native habitat it is and January. The dried, brown flowers often a deciduous tree to 20 feet tall, reported to remain for 4 to 6 weeks after color has faded. withstand slight frosts (4). Among gardeners opinions are divided as to the D. rotundifolia, said to have white or light desirability of this characteristic. Some con pink flowers, has not flowered here, and since sider the dried flowers attractive on the bush, it is not deciduous under Miami conditions we and others consider them unattractive. Regard believe that its cold requirements are not met. less of opinion, they are, when cut, in demand Statewide distribution of clonal material will for dry floral arrangements. determine these requirements and is aimed at Unfortunately the large bush size and pen releasing an excellent new ornamental Dom- dulous flower habit of the pollen parent (D. beya for central and northern Florida. wallichiiq are dominant. Therefore the hybrid Dombeya sp., Miami Station number 18317, has not become popular in Florida. was found in 1961 in a Coral Gables, Florida, In England, D. x cayeuxii sometimes is private garden. The plant attracted attention treated as an annual (6). Cuttings taken in because the flower heads were large and stood May flower in December and January. By the out in full view. The flowers, carried above time they flower the plants have attained a the dense foliage in large heads, are medium height of 4 feet and a spread of 3 feet, growing pink. The slightly recurved petals reflect the in 7 or 8 inch pots. light to make it an extremely showy plant when Seeds of D. nairobensis Engl, P. I. 194501 in bloom in January and February. It appears were received in 1950. This species is described to be unaffected by the lowest temperatures in as a small tree or shrub in its native habitat, the Miami area. east Central Africa (1). The two plants in our A seedling population resulting from open arboretum, after 14 years in the field, have pollinations of the clone was set in the field in reached a height of 6 feet. Cordate leaves 4 to 1964. This resulted in an amazing array of col 6 inches long are pubescent on both surfaces. ors from pure white, through 3 or 4 shades of Petioles are also pubescent. Both of the plants pink, to deep rose red, and with two individuals bear large flowers in pendulous umbels, with having purplish flowers. Variations occur in few flowers open at one time. One has pure flower size, shape, quantity, and number per white flowers. The other has pale pink flowers, cluster, as well as in leaf shape and bush form. with fringed petals that are a darker pink at Several plants from this population were selected the basal edges. Flowering occurs from Janu and propagated, and are being studied as pos ary through March. sible new ornamentals. D. TYiastersii came in 1952 under Miami sta Few individual plants possess attractive tion number 13463 and again in 1953 under form, as most have an extremely open appear number 13674. The two plants growing in the ance. Plants of this latter habit, despite the station arboretum are 5 feet tall, of open form. flower beauty, would be suitable only in loca Both surfaces of the large cordate leaves as well tions where they would be interplanted with as the petioles are pubescent. The flowers ap denser, better formed individuals. The poten 7 or more per umbel, but never in as large tial for breeding within this species is evident, quantities as are formed in the clusters of D. and work is progressing in this area. wallichii. The white flowers have a red splotch D. dregeana Sond. P. I. 221175 was re at the inside base of the petals. The base of the ceived in 1947 from South Africa. It has pure staminal column also is red. Neither of these white floors in sparse umbels, borne abundantly introductions are particularly attractive orna on the outside of the bush from October through mentals. December. D. rotundifolia Planch. P. I. 230894 was in The leaves are small and margins crenate. troduced in 1955 from Nyasaland. It is a shrub The growth habit is medium-dense with long 8 feet tall with a spread approximating its slightly pendulous stems, up to 10 feet. Since height. The form is loose, with long whip-like it has grown well on our limestone soil with a branches reaching out from a central crown. minimum of care, it is highly recommended as a SODERHOLM: DOMBEYA INTRODUCTIONS 479 species to be tried by the adventuresome home open pollination were collected from D. dregeana. gardener willing to depart from the use of the Pollen was transferred by bees from the two common-place garden subjects. adjacent plants of D. sp. aff. D. burgessiae, Dombeya sp. aff. D. burgessiae Gerrard, P. I. since no other Dombeyas were flowering at the 205654, (5) introduced originally into the time pollination occurred. Subsequent studies United States in 1951 as D. elegans, Cordem. is revealed that D. dregeana is self-incompatible thought to have come from the Island of Re and that pollen of D. sp. aff. D. burgessiae is union. It was released as the variety 'Rose- highly compatible on D. dregeana as well as mond* in 1967 by the Crops Research Division other species of Dombeya in the collection. after 6 years of studies of asexually propagated A resulting population of 202 plants was plants at the U. S. Plant Introduction Station. set in the field in July, 1963. Flower color, Clones from the original upright growing seed shape, and size; bush form, vigor, and size are lings were found to assume an almost hemi obvious variations which have appeared in this spherical shape, with no tendency to revert to group; and from it several individuals have the leggier condition of the parent plant. been selected for evaluation as new ornamentals. Dusty pink flower clusters are carried in Plants of two clones of this hybrid popula profusion over the entire surface of the bush tion were supplied to the Florida State High during November and December. The effect is way Department for use in its 1966 highway an outstanding display of color. beautification program. They were incorporated Plants of Dombeya Rosemound' were dis in the landscaping plans for the Palmetto By tributed to nurseryman and researchers in 1965. pass around Miami, and were placed in several One year later plant evaluation reports were locations near the southern end of the bypass. returned to us from recipients in Florida, Texas, The hybrids are vigorous growers; one flowers Pennsylvania, Virgin Islands, and France. in late September and the other in mid-October. Those reported on, 44 plants, were a small per Hybrids between D. sp., Miami number 18317 centage of the actual number distributed. and D. 'Rosemound' have been made and the Twenty-nine of the 44 had been planted out progeny is in its second year in the field. Ob doors or allowed to remain outside through the servations of precocious individuals that flow winter in large containers. Reports on the re- ered in 1966, suggest that it may be possible to results of cold injury varied considerably. In combine the excellent form of D. 'Rosemound' temperatures down to 38° F. no injury was with the brighter reds of introduction M 18317. noted. Between 30° and 37° seven plants were All of the Dombeyas tried thus far have uninjured and four slighlty injured. In all cases produced roots in propaation beds under inter injury consisted of discoloration or loss of mittent mist. However, ease of rooting varies leaves. Between 25° and 29° two plants were considerably with species and varieties. killed, two were injured, and three were not in Early studies showed that good results could jured. be obtained by soaking basal ends of 4 to 6 inch From this it can be concluded that Dombeya tip cuttings in 75 ppm water solution of indole- 'Rosemund' can be grown as far north as central butyric acid for 24 hours, and by placing the Florida, with occasional leaf and twig damage treated cuttings under intermittent mist in a to be expected. The range might be extended medium of perlite over 70° F. bottom heat. to include northern Florida if the plants are Insect problems on Dombeyas have been few pruned heavily following the early December at the Plant Introduction Station. Certain spe bloom and then protected until danger of frost cies and varieties are attacked by a leaf- is past. chewing insect; D. nairobensis is particularly Where flowering had occurred, the enthusi susceptible. Holes are frequently observed in the asm was overwhelming in praise of the floral center of the blades, but the insect producing display. Only one recipient mentioned that color them has not been found. The condition has not needed improvement; it was not "an intense been considered serious enough to require spe enough pink". cial control measures. The potential for new variety production As more Dombeya species are introduced by through breeding and selection among the Dom- the U. S. Department of Agriculture, through beyas appears excellent. the efforts of its plant explorers and cooperators In the spring of 1963 seeds resulting from in Africa, we hope to expand the area in which 480 FLORIDA STATE HORTICULTURAL SOCIETY, 1967

Dombeyas will be gown to include all of Florida 2. Menninger, Edwin A. 1958. What flowering tree is that? Edwin A. Menninger, Stuart, Florida. and the Gulf regions where fall and early winter 3. 1962. Flowering trees of the world for flowering shrubs are now in demand. tropics and warm climates. Hearthside Press Incorporated, New York. 4. Palmer, Eve and Norah Pitman. 1961. Trees of LITERATURE CITED South Africa. A. A. Balkema, Amsterdam and Gape Town. 5. Soderholm, Paul K. 1967. Domheya 'Rosemound' a 1. Eggeling, William J. and Ivan R. Dale. 1951. The new cultivar. Amer. Hort. Mag. 46(2): 91-92. indigenous trees of the Uganda Protectorate. 2nd ed. The 6. Taylor, F. W. 1966. Dombeya x cayeuxii. Gard. Government Printer, Uganda Protectorate. Chron. p. 85. Jan. 22.

COPPER AND OTHER NUTRIENT REQUIREMENTS OF 'BACCARA' ROSE IN LIGHTWEIGHT POTTING MEDIUM

S. E. McFadden Introduction

Florida Agricultural Experiment Station Efficiency in growing roses from small size Gainesville liner grade plants to salable size in containers requires a root environment optimal for growth. R. T. Poole This investigation was directed toward determin Hawaii Agricultural Experiment Station ing nutrient supplements needed to sustain Honolulu growth during the first 3 months in nurserycans when a standard lightweight rooting medium Abstract is used in place of potting media containing na tive soil. Measurements were made to determine effect Ideally, the level of nutrient elements present of 2 Cu, 4 P and 3 K levels in factorial com in a nurseryman's potting mixture should be bination on scion size and growth quality of the same each time it is prepared. One approach 'Baccara' rose on R. fortuniana rootstock grown toward this ideal is that of substituting syn for 3 months in 3-3-2 vol/vol mix of limed thetic or mined and processed products sphagnum peat, Perlome perlite and Turface (shredded styrafoam, vermiculite, perlite or baked clay with uniform monthly supplements baked clay) for the native soil ingredient that of N. Basic copper sulfate foliar spray pro is usually in nursery potting mixtures. The duced the greatest improvement in growth qual manufactured or processed materials have a ity rating, and regulated scion size response to more predictable chemical composition than lo supplements of P and K. The amount of 1026 cally available soils, and greater freedom from ppm available elemental K present in baked weed seed and parasite contaminants. Together clay ingredient of the potting mix, supplied with improved sanitation, the advantages of plant K requirement. Addition of K was found more uniform content and retention of nutrient to be unnecessary, whereas addition of Cu foliar elements may offset increased cost associated spray and P fertilizer were needed. Linear with eliminating the native soil ingredient from growth increase effects obtained from serial in potting mixtures. crements of P and K where no Cu spray was Combinations of processed mineral and or applied, and from serial increments of K where ganic materials provide the "soilless" rooting no P was added, are attributed to low levels of media frequently used in propagation of nursery Cu present in P and K fertilizer residue and stock. The same combinations used as media for filler materials. Cu deficiency effect on growth rooting stem cuttings can serve as media for of the test plant is described. growing plants, when appropriate elements are added to raise their generally low nutrient levels Florida Agricultural Experiment Stations Journal Series (4, 8, 11, 27). No. 2875.