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Growing Notes: The White Jacaranda

March 30, 2009

Plant Information

George H. Spalding
Lasca Leaves 18:41, 1968.

To the true plantsman few experiences can match the thrill of seeing the first seedlings of a new and unknown plant obtained from some distant part of the world. It requires patience to grow a plant to maturity and give it adequate testing. There is always the temptation to introduce a promising species quickly while initial enthusiasm is high, without waiting for it to reach maturity, or go through a cold winter, or undergo any one of the many other tests required before a plant can be considered ready for introduction.

When a plant has been fully tested and is ready for introduction, propagating stock plants are grown and made available to nurseries at cost of production. Although brief resumes are sent to trade journals when a new plant is released, to date no full account of Arboretum introductions has been published. So from time to time detailed reports of Arboretum plant introductions will appear in Growing Notes to provide a continuing official record.

One of the most interesting LASCA plant introductions is the so-called white jacaranda. This selection is considered a pure white form of acutifolia; however, such an albino variation has not been recorded in the Peruvian floristic literature. This accession, received in 1952, resulted from the efforts of Dr. Russell J. Seibert, then director of the Arboretum. While working in Peru in 1946 he had seen trees of this white form growing at the Agricultural Experiment Station of La Molina in Lima. It was reported at that time to have been introduced into cultivation from wild material found near Huanuco, Peru.

Feeling that this tree had great horticultural potential for Southern California, a successful attempt to obtain budwood was made resulting in the 1952 accession. Eleven dormant sticks were received. It has been reported that this jacaranda had been propagated by cuttings in Peru. The budwood sticks received were of thick caliper and failed to root when treated as cuttings. As soon as it became evident that the cutting method was not going to work, buds were taken and worked onto available rootstock of the typical Jacaranda acutifolia. Two of the budded seedlings “took,” but only one survived. This survivor provided buds for additional propagations two years later.

The original tree at the Arboretum first bloomed in 1957. Its flowers appeared in rather small trusses in this first season, but the color was a good clear white. Flowerings in later years have produced larger trusses, but while occasionally promising, the over-all performance is disappointing. Consequently, bloom has been erratic and not particularly effective. We do not know the reason for this poor performance, but believe it to be physiological in nature, or possibly poor adaptation to this particular region. If the cause can be found and removed, the white jacaranda will become a major addition to our list of outstanding flowering trees.

This jacaranda was offered to the trade through a notice in the Pacific Coast Nurseryman of April 1961 (Vol. 20, No. 4, pp. 20-21).

Thanks are due Austin Griffiths, Herbarium Curator at the Arboretum, for the suggestion that this series be undertaken.