An alternative use of some Cuphea spp. may be as a landscape or ornamental plant. Plants for special use in the landscape must cover bare ground, prevent erosion, add variety, tie-in different plants or add color (Georgia Cooperative Extension Service 1978, Plant Genetics and Germplasm Institute 1975). The cigar plant [C. ignea (DC)] is presently grown as an ornamental. Several selections of C. glutinosa, (Cham. & Schldl.), native to Brazil (Graham et al. 1981) have been identified with unique and desirable ornamental characteristics such as excellent ground cover and flowerings, and may have potential as ornamental ground cover for the southeastern United States. Cuphea procumbens x C. llavea hybrids have also been suggested as potential ornamental plants (Thompson et al. 1987).
Two tests were conducted on C. glutinosa during 1987-88; for environmental adaptation, and evaluation for desirable ornamental characteristics. The environmental adaptation test consisted of full sun and level soil, full sun and 30% slope, full shade (90% summer shade) under hardwood trees, and full shade (90% summer shade) under pine trees. All treatments had 10 replications of 5 cm plugs of rooted stems and seedlings of plant selection GA 16. Transplanting was on June 18, 1987. Plants were irrigated and fertilized as needed. Plants were evaluated for ground cover diameter and height, number of flowers, flower rating for attractiveness, and overall rating for growth and flowering 103 days after transplanting.
The 25 overwintering C. glutinosa selections were evaluated under full sun and level soil. Ten 5 cm plugs of rooted stems and seedlings of each Georgia selection were transplanted on June 24,1987. Plants were evaluated for ground cover diameter and height, leaf color, flower number and rating, and overall rating for growth and flowering 100 days after transplanting and were evaluated again during May and June of the following year.
C. glutinosa stems and leaves higher than 5 cm above the ground were usually killed by the cold weather while the stems and leaves next to the ground, and which completely cover the soil remained attractive and green throughout the winter. The lowest temperature in the 1987-88 winter was -7°C. The plants blossomed from early April until the first autumn freeze, about mid-November at Tifton Georgia. Flowers are light purple and have 1 to 6 petals per flower. For 6 petal flowers, the 4 ventral petals are about 0.8 x 0.2 cm while the 2 dorsal petals are 0.6 x 0.4 cm. Leaves are 1.5-2.0 x 0.5 cm. C. glutinosa survived overwintering and may be propagated by rooting of the stoloniferous shoots, by underground stolons and by seeds.
C. glutinosa will not tolerate shade, but requires full sun for optimum growth (Table 1). Growth was significantly reduced on the 30% slope, but this was probably due to weed competition. We believe that plant growth on 30% slope would have been much better if the site had been free of grass and broadleaf weeds at time of planting.
The 25 overwintering C glutinosa selections exhibited many differences in ground cover, leaf color, plant height, flowering, number of petals per flower and overall appearance (Table 2). Selection of GA 21 was based on overwintering, superior ground cover, short height superior leaf color, 6 petal flowers and superior flowering number and color. The selection of GA 23 was based on its overwintering, superior ground cover, relative tall plant fair to superior leaf color, 6 petal flowers and superior flowering number and color. GA 20 was selected for overwintering, good ground cover, medium height, fair to superior leaf color, 6 petal flowers and superior flowering. These 3 C. glutinosa selections have value as ornamental ground cover in commercial and residence landscaping. These 3 selections may also have value for erosion control and beautification along highways and as potted plants. The erosion control comes from the ground being completely covered with a dense mat of shoots near the soil.
|Environmental treatment||Diameter (cm)||Height (cm)||(No./225 cm2)||Visual (rating)y||Visual (rating)x|
|Full sun and level soil||52aw||13a||15a||4a||8a|
|Full sun, 30% slope||16b||8b||1b||2b||3b|
|Full shade, hardwood||3c||4c||1b||1c||1c|
|Full shade, pine||3c||3c||0b||1c||1c|
|Fall 1987z||Spring 1988|
|Georgia selection code||Diameter (cm)||Height (cm)||Leaf colory (rating)||(No./225 cm2)||Visual (rating)x||Visual (rating)w||Height (cm)v||(No./225 cm2)u||(No. petals)t|