Landscape Trees for Energy Conservation--South Florida Trees¹

R.J. Black²

The use of landscape materials to moderate effects of adverse climates is not a new concept, but is receiving considerable attention in view of the current emphasis on energy conservation. Residential utility rates have escalated substantially to warrant adoption of any number of conservation measures. Collectively, measures such as skilled landscaping, increased insulation, solar hot water heaters, adjusted thermostat levels, and others can result in significant savings to the homeowner.

It has been estimated that the potential value of "low energy" landscapes can result in a 20-30% reduction in energy consumption. Presently, residential energy use in Florida accounts for 23% of the total energy budget. Investing in new plantings not only provides pleasure from an aesthetic sense, but will have direct benefits in reducing future energy consumption.

A major benefit of landscaping is to limit solar radiation on windows and exterior walls. In south Florida (see Figure 1) during the five-month period from mid-May to mid-September, temperatures exceed human comfort levels. Trees are the most effective form of plant material for limiting solar radiation. Proper placement should ensure maximum shading. Tree shade can be most effective on the surfaces of east and west sides of residences.

Figure 1. Florida regions.

The altitude of the sun is sufficiently high during summer months that solar loads on south-facing walls are minimal. When the sun is directly overhead, trees provide little benefit since most canopies do not extend over the roof. Roof insulation is generally adequate to prevent elevated internal temperatures. Deciduous trees can be used effectively in south Florida during winter months (November-February) when the warming effect of the sun can be beneficial.

Information presented in the tables in this publication should assist the homeowner and designer in selecting trees for south Florida. Trees have been classified and presented according to size, density of shade, rate of growth and whether they are evergreen or deciduous. General information has been included in the notes column on items such as surface roots and flowering character, among others.

• Table 1 . South Florida Trees--Small (Mature tree height shorter than 25 feet)

• Table 2 . South Florida Trees--Medium (Mature tree height 25-40 feet)

• Table 3 . South Florida Trees--Large (Mature tree height taller than 40 feet)

Three size classifications have been used: small less than 25 feet (7.5m), medium - 25-40 feet (7.5m 12.2m), and large - over 40 feet (12.2m). Small trees are best used as patio trees or they can be planted relatively close to the house to block morning and afternoon sun directly. Medium trees, because of their canopy and size, provide extensive shade on lawns and patios. They limit solar radiation by direct blocking or by casting shadows on wall surfaces. Generally, medium trees should be planted 10 to 15 feet (3-4.6m) away from the house. Large trees and those with wide spreading canopies should be restricted to the perimeters of most residential lots.

Tree form is quite variable and accordingly shade patterns vary with each form. The forms used are horizontal spreading, rounded, vase, pyramidal, and oval.

Maximum shading is provided by horizontal spreading forms, but unfortunately, not many small or medium trees exist in this form. Rounded or oval forms can be just as effective if multiple plantings are used. Pyramidal forms are least effective. Remember that the shadow of a broad tree with a low canopy moves much more slowly than the shadow of a tall, slender tree.

Density of tree canopies can have as much effect as tree form on solar reduction. Density of shade is related to the size of the foliage and the general compactness of the crown as influenced by branching habit, number of leaves, and internode length. Trees have been classified according to light, moderate, or heavy shading, but even these are approximations since cultural practices can have a major influence on the density of a tree's growth.

Growth rate and initial planting size will ultimately determine how quickly benefits will be derived from newly installed plantings. Generally, the largest affordable tree available to most homeowners is one with a stem caliper of 2-3 inches (5.0-7.6 cm), an overall height of 8-10 feet (2.4-3.0 m), and a spread of 3-4 feet (0.9-1.2 m). The lowest limbs are usually 3-4 feet (0.9-1.2 m) from the soil surface. A tree with a fast growth rate generally grows more than 3 feet (0.9 m) during one growing season, whereas trees with moderate growth rates grow from 2-3 feet each year (0.6-0.9 m) and slow-growing trees grow less than 2 feet (0.6 m) annually.

Every effort should be made to determine conditions present on your site with regard to light intensity, soil pH, soil drainage, and soil type. Your county agent or local nursery can assist you in selecting trees appropriate for your site conditions. Information contained in Fact Sheet ENH-22 "Ornamental Trees for South Florida," can provide additional cultural information on a number of trees listed in this publication.

Tables

Table 1. South Florida Trees--Small (Mature tree height less than 25 feet)

Common Name	Scientific Name	Leaf Persistence1	Form2	Shade Density3	Growth Rate4
Bucida	Bucida spinosa	E	O	L	S
Remarks: Wind and salt tolerant.
Carambola	Averrhoa carambola	E	R	H	M
Remarks: Free flowering. Delicious fruit produced two or three times per year.
Citrus-leaf bottlebrush	Callistemon citrinus	E	O	M	M
Remarks: Red flowers in spring. Accent trees. Can tolerate a damp site.
Citrus trees	Citrus spp.	E	R	H	M
Remarks: Fragrant flowers. Adaptable to many uses. Roots not aggressive.
Frangipani	Plumeria rubra	D	V	M	F
Remarks: Fragrant showy flowers.
Geiger tree	Cordia sebestena	E	R	M	M
Remarks: Burnt orange to vermillion flower. Peak flowering in June and July. Slow in poor sites.
Golden shower	Cassia fistula	D	O	M	F
Remarks: Seed pods messy. Attractive yellow flowers.
Ipe	Tabebuia impetiginosa	D	V	L	M
Remarks: Attractive pink and purple flowers.
Jaboticaba	Myrciaria cauliflora	E	V	H	S
Remarks: Slow to establish. Free flowering. Black fruit of grape-like flavor.
Jerusalem thorn	Parkinsonia aculeata	D	S	L	F
Remarks: Irregular habit. Late spring flowers. Often picturesque trunk.
Loquat	Eriobotrya japonica	E	R	H	F
Remarks: Low canopy. Coarse texture. Fragrant late fall or winter.
Madagascar olive	Noronhia emarginata	E	O	M	M
Remarks: Coarse texture. Durable tree for seaside locations.
Orchid tree	Bauhinia spp.	D	R	M	M
Remarks: Favored flowers on B. blakeana (medium tree). B. variegata has been evaluated using the UF/IFAS invasive plant criteria and it should be avoided in south Florida.
Pigeon plum	Coccoloba diversifolia	E	V	M	M
Remarks: Accent tree. Interesting bark.
Pink trumpet tree	Tabebuia heterophylla	E	O	M	M
Remarks: Excellent street tree. Pink flowers.
Sea grape	Coccoloba uvifera	E	S	M	M
Remarks: Edible fruit.
Shaving brush	Pseudobombax ellipticum	D	S	M	F
Remarks: Pink flowers when the tree is bare.
Silver buttonwood	Conocarpus erectus \var. sericeus	E	R	L	F
Remarks: Very good tolerance for salt.
Silver trumpet tree	Tabebuia caraiba (T. argentea)	D	O	M	M
Remarks: Attractive yellow flowers.
Sweet acacia	Acacia farnesiana	E	V	M	F
Remarks: Thorny. Not suitable for play area.
Torch tree	Dais continifolia	E	O	M	M
Remarks: Good for small patio. Clusters of rosy pink flowers.
Wax myrtle	Myrica cerifera	E	R	M	M
Remarks: Patio tree. Often multi-stemmed.
Weeping bottlebrush	Callistemon viminalis	E	R	M	M
Remarks: Weeping habit. Showy red spring flowers.
Yellow elder	Tecoma stans	E	R	M	F
Remarks: Yellow flowers.
1Leaf Persistence: E = Evergreen; D = Deciduous 2Form: R = Round; V = Vase; S = Spreading; O = Oval; P = Pyramidal 3Density of Shade: L = Light; M = Moderate; H = Heavy 4Growth Rate: S = Slow; M = Medium; F = Fast

Table 2. South Florida Trees--Medium (Mature tree height 25-40 feet)

Common Name	Scientific Name	Leaf Persistence1	Form2	Shade Density3	Growth Rate4
Apple blossom cassia	Cassia javanica	D	S	M	F
Remarks: Pink and white blossoms with new leaves.
Avocado	Persea americana	E	R	H	F
Remarks: Edible fruit. Low branching when young.
Bulnesia	Bulnesia arborea	E	S	H	M
Remarks: Yellow flowers. Growth faster when established.
Buttonwood	Conocarpus erectus	E	V	M	M
Remarks: Excellent for seaside. Silver-leaved variety smaller.
Fiddle-leaf fig	Ficus lyrata	E	R	H	M
Remarks: Not very aggressive.
Gumbo limbo	Bursera simaruba	D	R	M	F
Remarks: Conspicuous bark.
Harpullia	Harpullia arborea	E	R	M	M
Remarks: Interesting red fruits and black seeds.
Hong kong orchid	Bauhinia blakeana	E	S	M	M
Remarks: Flowers from late fall to spring. Intense flower color.
Indian laurel	Calophyllum inophyllum	E	O	H	M
Remarks: Picturesque branches. Fragrant.
Jacaranda	Jacaranda mimosifolia	D	S	L	F
Remarks: Fern-like foliage. Showy blue flowers in spring.
Karum tree	Pongamia pinnata	D	S	M	F
Remarks: Litter problem with leaves and pods.
Mimusops	Manilkara roxburghiana	E	R	H	S
Remarks: Durable in wind. Salt tolerant. Edible fruit.
Norfolk Island pine	Araucaria heterophylla	E	P	M	M
Remarks: Formal specimen tree.
Paradise tree	Simarouba glauca	E	R	M	S
Remarks: Pleasing form. Yellow flowers in spring.
Queen crape myrtle	Lagerstroemia speciosa	D	S	M	M
Remarks: Masses of pink and lavender flowers. Low maintenance.
Red maple	Acer rubrum	D	S	M	F
Remarks: Suitable for sites with excess moisture. Short lived.
Sausage tree	Kigelia pinnata	E	P	H	M
Remarks: Messy.
Tamarind	Tamarindus indica	E	R	M	S
Remarks: High wind resistance. Litter of seed pods. Handsome form.
Weeping podocarpus	Podocarpus gracilior	E	O	H	M
Remarks: Weeping habit. Fine texture.
West Indian mahogany	Swietenia mahagoni	D	S	M	M
Remarks: Interesting fruit.
Wild tamarind	Lysiloma bahamensis	E	V	L	M
Remarks: May lose most of its leaves.
Yellow poiniciana	Peltophorum pterocarpum	D	S	M	F
Remarks: Yellow flowers. Seed litter. Surface roots may be a problem.
Yellow trumpet	Tabebuia chrysotricha	E	V	L	M
Remarks: May lose its leaves when yellow blooms appear.
1Leaf Persistence: E = Evergreen; D = Deciduous 2Form: R = Round; V = Vase; S = Spreading; O = Oval; P = Pyramidal 3Density of Shade: L = Light; M = Moderate; H = Heavy 4Growth Rate: S = Slow; M = Medium; F = Fast

Table 3. South Florida Trees--Large (Mature tree height taller than 40 feet)

Common Name	Scientific Name	Leaf Persistence1	Form2	Shade Density3	Growth Rate4
Bald cypress	Taxodium distichum	D	P	L	F
Remarks: Flat-topped to spreading when mature. Fine foliage.
Black olive	Bucida buceras	E	R	M	M
Remarks: Tender. Massive with age.
Floss silk tree	Chorisia speciosa	D	S	M	F
Remarks: Showy pink flowers. Needs plenty of room.
Laurel oak	Quercus laurifolia	D	O	H	F
Remarks: Appropriate for street plantings.
Litchi, lychee	Litchi chinensis	E	R	H	M
Remarks: Edible, colorful fruit. Excellent specimen and shade tree.
Live oak	Quercus virginiana	E	S	M	M
Remarks: Long-lived. Little maintenance. Fine avenue tree.
Mango	Mangifera indica	E	R	H	M
Remarks: Edible fruit.
Red silk cotton tree	Bombax ceiba	D	S	M	M
Remarks: Spiny trunk and branches. Red to orange-red flowers in winter.
Royal poinciana	Delonix regia	D	S	M	F
Remarks: Litter problem. Attractive orange-red flowers.
Shortleaf fig	Ficus citrifolia	E	S	M	M
Remarks: Native.
1Leaf Persistence: E = Evergreen; D = Deciduous 2Form: R = Round; V = Vase; S = Spreading; O = Oval; P = Pyramidal 3Density of Shade: L = Light; M = Moderate; H = Heavy 4Growth Rate: S = Slow; M = Medium; F = Fast

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Footnotes

1. This document is ENH-50 (which supersedes OH-50), one of a series of the Department of Environmental Horticulture, Florida cooperative extension service, Institute of Food and Agricultural Sciences, University of Florida. Date first printed: September 1982. Reviewed: June 1997. Revised: October 2003. Please visit the EDIS website at http://edis.ifas.ufl.edu

2. R.J. Black, professor emeritus, Department of Environmental Horticulture, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611.

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