Edward F. Gilman, Dennis G. Watson, Ryan W. Klein, Andrew K. Koeser, Deborah R. Hilbert, and Drew C. McLean
Introduction
Pongam is a fast-growing evergreen tree which reaches 40 feet in height wit up to a 55-foot spread, forming a broad, spreading canopy casting moderate shade. The six- to nine-inch-long, pinnately compound, shiny dark green leaves are briefly deciduous, dropping for just a short period of time in early spring but being quickly replaced by new growth. Pongam is at its finest in the spring when the showy, hanging clusters of white, pink, or lavender, pea-like, fragrant blossoms appear, the clusters up to 10 inches long. These beautiful blossoms and the glossy, nearly-evergreen leaves help make pongam a favorite for use as a specimen, shade, or windbreak. It has also been planted as a street tree, but dropping pods often litter the ground. However, the seeds which are contained within the oval, 1 ¼-2-inch-long, brown seedpods are poisonous, a fact which should be considered in placing the tree in the landscape, if many children are present.
Figure 1. Full Form - Millettia pinnata: pongam Credit: UF/IFAS
General Information
Scientific name: Millettia pinnata
Pronunciation: mil-LET-ee-uh pih-NAY-tuh
Common name(s): Pongam, Karum tree, poonga-oil tree
Family: Fabaceae
USDA hardiness zones: 10B through 11 (Figure 2)
Origin: native to southeast Asia, Australia, and the western Pacific Islands
UF/IFAS Invasive Assessment Status: invasive and not recommended except for "specified and limited" use approved by the UF/IFAS Invasive Plant Working Group (North, Central, South)
Uses: specimen; shade; deck or patio; highway median; street without sidewalk; tree lawn 4-6 feet wide; tree lawn > 6 ft wide; parking lot island 100-200 sq ft; parking lot island > 200 sq ft
Figure 2. Range
Description
Height: 30 to 40 feet
Spread: 30 to 55 feet
Crown uniformity: symmetrical
Crown shape: round
Crown density: dense
Growth rate: fast
Texture: medium
Foliage
Leaf arrangement: alternate
Leaf type: odd-pinnately compound; made up of 5-9 leaflets but most often 7
Leaf margin: entire
Leaf shape: elliptic (oval)
Leaf venation: pinnate
Leaf type and persistence: evergreen
Leaf blade length: 6 to 8 inches; leaflets are 3 to 4 inches
Leaf color: dark green and shiny on top, paler green underneath
Pongam should be grown in full sun or partial shade on well-drained soil. A relatively low-maintenance tree once established, pongam is resistant to high winds and drought but is susceptible to freezing temperatures below 30-degrees F. Pongam will show nutritional deficiencies if grown on soil with a pH above 7.5.
Space major limbs along the trunk to increase the structural strength of the tree. Keep limbs less than two-thirds the diameter of the trunk to help ensure that branches are well secured to the tree.
Propagation is by seed.
Pests
No pests are of major concern, but caterpillars occasionally cause some defoliation.
Diseases
No diseases are of major concern.
Additional References
Koeser, A.K., Friedman, M.H., Hasing, G., Finley, H., Schelb, J. 2017. Trees: South Florida and the Keys. University of Florida Institute of Food and Agricultural Sciences.
